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Biomedical subjects

Y Ménézo

Publications and source records attributed to Y Ménézo.

At least 19 recordsLinked to original sources
PubMed2005

[Impact of sperm DNA fragmentation on ART outcome].

We have used the sperm chromatin structure assay (SCSA) test in order to determine if correlations can be found between sperm DNA fragmentation and spermogram parameters. Only necrospermia and DNA fragmentation index are strongly correlated (P<0.0001). Neither fertilization rates for ICSI and IVF, nor blastocyst formation rates are impaired by a high DFI. However when the critical DFI>30% is reached, the chances of having ongoing pregnancies after blastocyst transfer are reduced by three. Treatments with antioxidants are of limited efficacy even though we obtained 2 deliveries after DFI treatments with such treatments. New strategies in order to improve the pregnancy rates for these peculiar cases of reduced fertility are discussed.

Adult↗
PubMed2004

Effect of injecting collagenase into the uterine artery during a caesarean section on the placental separation of cows induced to calve with dexamethasone.

A caesarean section was performed on 30 cows before normal term and 16 to 20 hours after the induction of parturition with dexamethasone. During the surgical procedure, 20,000 U of bacterial collagenase was injected into the uterine artery of 15 of the cows. The average periods of retention of the fetal membranes were 40 hours in the treated cows and 114 hours in the control cows (P<0.001). At 36 hours after the surgery six of the treated cows (40 per cent) but all 15 of the control cows had retained fetal membranes. The collagenase-treated cows showed no abnormal clinical signs during the 10 days after the operation.

Animals↗
PubMed2002

[LH and gamete quality].

UNLABELLED: Potential contribution of LH to controlled ovarian stimulation in the final maturation of the oocyte and in preparation of the endometrium. LH and oocyte maturation LH and implantation Implantation rate variable but increased with LH/hCG, probably due to fewer abortions. CONCLUSION: Is LH/hCG is an immunomodulator but it may have a positive impact on the quality of the gametes through cytoplasmic improvement.

Chorionic Gonadotropin↗
PubMed2001

In vitro fertilization and blastocyst transfer for carriers of chromosomal translocation.

Blastocyst transfers (BT), may benefit chromosomal translocation-carrier couples who suffer multiple miscarriages or are unable to achieve pregnancy following classical ART techniques. In vitro culture applies an additional selection pressure, so that those embryos which achieve blastocyst formation have higher survival probability as healthy balanced translocation carriers or unaffected embryos. Sixteen IVF cycles were performed in 11 patients. When blastocyst are obtained, implantation rate per blastocyst and delivery rates (7/11 cycles, eight healthy babies born) are high. However, the overall blastocyst formation rate is low (20%), and as a consequence in nearly half of the cycles, no blastocyst can be obtained. We propose that this strategy may be used initially as an alternative or a complement to preimplantation genetic diagnosis, and to apply the forces of natural selection in vitro.

Adult↗
PubMed2001

Taurine and hypotaurine in spermatozoa and epididymal fluid of cats.

Taurine and hypotaurine have been found in spermatozoa and seminal plasma of numerous species and are known to have beneficial effects on sperm characteristics in mammals. Taurine is considered an essential dietary constituent in cats. Dietary deficiency has been associated with a range of serious clinical disorders. Quantification of taurine and hypotaurine in the genital tracts of male cats has not been reported. In this study, the concentrations of taurine and its precursors were measured in serum, spermatozoa, epididymal fluid and seminal plasma from cats. The concentrations of taurine measured in serum samples confirmed that the cats were not deficient in taurine. Significant amounts of taurine and hypotaurine were found in spermatozoa, seminal plasma and epididymal flushing fluid. Hypotaurine was not detected in serum samples. These results indicate that hypotaurine may be synthesized in cat testes or epididymides. Cysteamine was not detected in any of the samples.

Animals↗
PubMed2000

Mammalian oviduct and protection against free oxygen radicals: expression of genes encoding antioxidant enzymes in human and mouse.

Genetic expression of five antioxidant enzymes involved in mechanisms protecting embryos against reactive oxygen species (ROS) was studied in human and mouse oviducts. The presence of transcripts encoding for gamma-glutamylcysteine synthetase (GCS), glutathione peroxidase (GPX), Cu-Zn-superoxide dismutase (Cu-Zn-SOD), Mn-superoxide dismutase (Mn-SOD) and catalase was analysed by use of the reverse transcription-polymerase chain reaction (RT-PCR). Different expression profiles of transcripts encoding for these enzymes were observed between human and mouse oviducts. In the mouse, all transcripts encoding for the enzymes tested were present in oviduct. In human, only transcripts encoding for GPX, Cu-Zn-SOD and catalase were also detected in oviduct. However, GCS and Mn-SOD transcripts were never observed in human oviduct. Cu-Zn-SOD transcripts are relatively highly expressed whatever species. These results suggest that different gene expression patterns of these antioxidant enzymes between human and mouse may reflect the variations in the ability of embryos to develop in vivo and in vitro. However, hormone related-expression of the missing transcripts in human cannot be ruled out.

Animals↗
PubMed2000

Comparison between day-2 embryos obtained either from ICSI or resulting from short insemination IVF: influence of maternal age.

Short incubation time prevents deleterious effects of cumulus cell degeneration and excess spermatozoa in IVF embryos. We performed a short incubation (3 h) protocol in 328 IVF cycles, in order to compare the developmental potential of regular IVF embryos with those originating from 316 cycles entered our intracytoplasmic sperm injection (ICSI) programme over the same period. Embryo transfers were performed in all patients on day 2. The mean number of embryos transferred was 1.92 for the ICSI group and 1.73 for the IVF group (P < 0.007). This was related only to the wishes of patients. However, the policy of the centre is to transfer a low number of embryos in young patients in order to avoid multiple pregnancies. All spare embryos were permitted to grow to the blastocyst stage for freezing. Shortening incubation time did not decrease fertilization rates. In our overall population, no difference was observed in the implantation rates per embryo for IVF (19%) or for ICSI (20%). An age-related decrease in embryo production was observed for both groups of patients (P < 0.01 for ICSI and P < 0.001 for IVF). The age-related decrease in embryo implantation was only significant for the IVF group (P < 0.03 for patients <30 and >35 years of age). A significant overall decrease in blastocyst formation was observed for spare embryos after ICSI versus IVF (34.2 versus 43.8%; P < 0. 05). The significance of this observation is discussed.

Adult↗
PubMed1999

In vitro capacitation of dog spermatozoa as assessed by chlortetracycline staining.

We developed an assay for detecting capacitation and acrosome status in dog spermatozoa using chlortetracycline (CTC) as a fluorescent probe. Sperm cells were stained after incubation in modified canine capacitation medium (mCCM). Calcium ionophore A23187 permitted the induction of acrosomal exocytosis of capacitated sperm cells. Spermac staining and transmission electron microscopy were used as control tests to detect acrosome-reacted spermatozoa. Three different patterns of CTC distribution in the spermatozoa were found. These patterns were similar to those observed in other mammalian species. The CTC test was used to monitor the time course of the capacitation process in dogs. It was found that the kinetics of capacitation in canine sperm cells are similar to those observed in other mammals.

Acrosome Reaction↗
PubMed1999

Effect of lecithin on in vitro and in vivo survival of in vitro produced bovine blastocysts after cryopreservation.

The use of soybean lecithin in an glycerol-based solution for slow freezing of in vitro matured, fertilized and cultured (IVMFC) bovine embryos was examined. Embryos were developed in vitro in INRA Menezo's B2 medium supplemented with 10% fetal calf serum (FCS) on Vero cells monolayers. Day 7 blastocysts were frozen in a two-step protocol consisting of exposure to 5% glycerol and 9% glycerol containing 0.2 M sucrose in F1 medium + 20% FCS. Soybean lecithin was either added or not to the freezing solutions at a final concentration of 0.1% (w/v). In Experiment 1, blastocysts were equilibrated in cryoprotectant solutions without cooling. Cryoprotectant was diluted from embryos with 0.5 M and 0.2 M sucrose. The percentages of fully expanded and hatched blastocysts treated with or without lecithin after 24 and 48 h in culture were not significantly different (100 versus 100% and 93.3 versus 100%, respectively). In Experiment 2, the in vitro survival of frozen-thawed IVMFC blastocysts was compared when cryoprotectant solutions were either supplemented or not with lecithin. No significant effect of lecithin was found on the ability of frozen-thawed blastocysts to re-expand after 48 h in culture (65.6 and 54.2%, respectively). However, the post-thaw hatching rate of embryos cryopreserved in the presence of 0.1% lecithin was significantly higher after 72 h in culture (52 and 31.8%, respectively). In Experiment 3, the ability of frozen-thawed IVMFC blastocysts to establish pregnancy following single embryo transfer was determined. Transfers of 58 and 66 frozen-thawed embryos cryopreserved with or without lecithin resulted in 6 and 10 (10.3 and 15.1%, respectively) confirmed pregnancies at Day 60. Addition of lecithin to cryoprotectants did not improve the in vivo development rate of cryopreserved IVMFC bovine blastocysts.

Animals↗
PubMed1999

Use of co-culture of human embryos on Vero cells to improve clinical implantation rate.

Co-culture of human embryos (n = 384 cycles) to the blastocyst stage using Vero cell monolayers was carried out between August 1995 and December 1997. A total of 2868 zygotes were co-cultured and 1027 embryos reached the blastocyst stage (blastocyst formation rate 35.8%). The blastocysts were frozen in 43.7% of patients. A mean of 1.8 blastocysts was transferred per patient and 95 pregnancies were obtained (pregnancy rate/cycle 24.7%). The blastocyst implantation rate was 23.6%. Miscarriage occurred in 15 patients (15.7%) and ectopic pregnancy in three (3.1%) patients. The multiple pregnancy rate was 32.6%. No differences were observed in the blastocyst rate between poor, normal or high response patients. Blastocyst formation was significantly lower when frozen donor spermatozoa were used. Significantly higher pregnancy rates per transfer and blastocyst implantation rates were attained when embryos were transferred on days 5 or 6 compared with day 7. No advantage was observed when co-culture was used in first cycle IVF patients, in comparison with conventional day 2 replacements. The use of blastocysts for preimplantation genetic diagnosis (PGD) increases the diagnostic reliability and widens diagnostic possibilities. A total of 215 cycles with frozen-thawed co-cultured blastocysts were carried out, with a pregnancy rate of 22.7% per replacement.

Adult↗
PubMed1999

Expression of genes encoding antioxidant enzymes in human and mouse oocytes during the final stages of maturation.

The mRNA expression of five enzymes: catalase, Cu-Zn-superoxide dismutase (Cu-Zn-SOD), Mn-superoxide dismutase (Mn-SOD), glutathione peroxidase (GPX), and gamma-glutamylcysteine synthetase (GCS) each involved in protection against free radicals was studied in human and mouse oocytes. In the mouse, oocytes were collected at different stages of maturation in order to determine the storage of these transcripts. For the human, germinal vesicle (GV) oocytes harvested during intracytoplasmic sperm injection (ICSI) procedures and failed fertilized metaphase II (MII) oocytes were analysed. Human and mouse were compared in order to determine whether the differential developmental capacity of mouse and human preimplantation embryos in culture could be explained by the variations in the patterns of expression for these enzymes. mRNA expression for these enzymes was examined using reverse transcription-polymerase chain reaction (RT-PCR). In the mouse, all transcripts (except for catalase) were detected, whatever the maturation stage. No qualitative differences were detected between GV and MII oocytes. In human, all the enzymes (except for catalase) were expressed in MII oocytes and Cu-Zn-SOD was particularly highly expressed. Transcripts corresponding to GPX and Mn-SOD were not detected at GV stage but only at MII stage, suggesting that storage could occur between GV and MII stages. However, using 3' end-specific primers for GPX and Mn-SOD, instead of the oligo(dT)(12-18) primer, for the reverse transcription reaction, the transcripts for these antioxidants enzymes have been detected in human oocytes at the GV stage. This suggests the presence of maturation-specific polyadenylation of these transcripts. These enzymes can be considered as markers of cytoplasmic maturation.

Animals↗
PubMed1999

[Sequential media: why and how?].

Blastocyst transfer is highly recommended for the following indications to avoid repeated failure of implantation: related to maternal, paternal and cytogenetic aspects on the embryonic side and/or uterus motility. Sequential media have now replaced coculture in order to produce blastocysts. The basic idea of sequential media is to follow embryo's need. There are 2 phases during preimplantation period: the first one corresponds to a development through maternal stores, gathered during maturation, before genomic activation. This requires a complete protection against free radicals (through EDTA), and a decrease in the concentration of glucose and phosphate: mitocondrial function is impaired. Regulation of the endogenous pool is not perfect. Then at the time of genomic activation, there is an increased need for numerous metabolites. Insulin can be added as the I-Receptor appears at the 8-cell stage. The medium used during this phase has to be rich.

Coculture Techniques↗
PubMed1999

Confirmation of diagnosis in preimplantation genetic diagnosis (PGD) through blastocyst culture: preliminary experience.

Three cases of preimplantation genetic diagnosis (PGD) (two for sexing and one for aneuploidy screening) are presented. Embryo biopsy was performed at day 3 and diagnosis was established with fluorescent in situ hybridization (FISH). Embryos not used for replacement were cultured in sequential media for blastocyst development. Blastocyst rate was 39.3 per cent. Confirmations of diagnosis were established with FISH in blastocysts and arrested embryos. Mosaicism was observed in 7/8 blastocysts (mean number of cells analysed: 55.5) and 5/8 arrested embryos. The percentage of abnormal cells was 17.1 per cent for blastocysts and 54 per cent for arrested embryos. Polypoid cells were observed in 4/8 blastocysts. Confirmation of diagnosis at the blastocyst stage is a useful tool in PGD.

Aneuploidy↗
PubMed1998

Precursors of taurine in female genital tract: effects on developmental capacity of bovine embryo produced in vitro.

Two precursors of taurine have been studied: cysteamine and hypotaurine. Cysteamine has been quantified in genital secretions and found in follicular fluids of all species tested. On the contrary cysteamine was not detected (or traces) in tubal fluids of the same species. Addition of 50, 100 or 250 microM of cysteamine to the maturation medium used in the culturing of bovine oocytes did not improve the cleavage rate nor the embryo's developmental potential in vitro. Furthermore, at 250 microM, cysteamine seems to be toxic to the embryo. Addition of 0.5-1 mM hypotaurine to the bovine embryo culture medium improved significantly blastocyst production and quality. The respective roles of these 2 taurine precursors on maturation and embryo development are discussed.

Animals↗
PubMed1998

Improved methods for blastocyst formation and culture.

Transfer at the blastocyst stage has been proposed to increase the pregnancy rates after in-vitro fertilization (IVF) and embryo transfer. In the first period of experiments, culture in a single medium, from fertilization to blastocyst led to disappointing results: low blastocyst formation rates and low implantation rates per blastocyst transferred. Then the period of co-culture began (starting with animals in the early 1980s and with humans in the early 1990s). With this technique, using tubal or granulosa cells or layers obtained from established cell lines of transport epithelium origin, blastocyst formation has reached approximately 50% and the overall implantation rate is approximately 25%. The embryos obtained have high numbers of cells (> 200 cells for a day 6 expanded blastocyst). Co-culture with fibroblasts has been found to be useless. This technology has been proven reliable and reproducible: Blastocyst formation is highly dependent on maternal and paternal factors. It has enabled the design of efficient freezing and thawing protocols. Numerous interesting observations have been obtained to reach the third period, i.e. the use of sequential media. A simple medium is used for fertilization, then another one is used from fertilization up to the 4-cell stage (beginning of waves of transcription), then a third medium is used for development up to the blastocyst stage. The results obtained seem very similar to the one obtained with co-culture. Obviously it is now time, in humans, to switch to sequential media.

Animals↗
PubMed1997

Glycine and methionine transport by bovine embryos.

As glycine is one of the most concentrated amino acids in the female genital tract, we investigated its uptake by bovine in vitro matured/in vitro fertilised blastocysts in the presence of increasing concentrations of radiolabelled glycine. We also determined methionine uptake by in vitro and in vivo produced embryos. In our study, the hypothesis of more than one site of enzyme activity for glycine substrate was not validated. We determined a Vmax of 23.4 fmol/min per embryo and a K(m) value of 13.3 microM. No significant difference was observed either between in vivo and in vitro derived embryos or between grade 1 and grade 2 embryos for methionine uptake. The methionine and glycine uptake of a day 7 bovine was similar to that of a day 4 mouse blastocyst. This is rather low if we consider the relative cell numbers.

Animals↗
PubMed1997

Laser blastocyst biopsy for preimplantation diagnosis in the human.

A new methodology for blastocyst biopsy that uses a 1.48 microm diode laser is described. Trophectoderm cells are biopsied after laster zona drilling and culture, fixed and processed for fluorescent in situ hybridisation (FISH) analysis. Preliminary results on the efficiency of the procedure and blastocyst recovery rate are promising. Blastocyst laser biopsy is a useful tool in preimplantation genetic diagnosis (PGD) as it allows a more reliable diagnosis and widens the diagnostic possibilities on account of the higher number of cells obtained in the biopsy.

Biopsy↗