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Biomedical subjects

M Plachot

Publications and source records attributed to M Plachot.

At least 37 records · Page 2Linked to original sources
PubMed1998

Chromosome methylation patterns during mammalian preimplantation development.

DNA methylation patterns were evaluated during preimplantation mouse development by analyzing the binding of monoclonal antibody to 5-methylcytosine (5-MeC) on metaphase chromosomes. Specific chromosome patterns were observed in each cell stage. A banding pattern predominated in chromosomes at the one-cell stage. Banding was replaced at the two-cell stage by an asymmetrical labeling of the sister chromatids. Then, the proportion of asymmetrical chromosomes decreased by one-half at each cell division until the blastocyst stage, and chromosomes became progressively symmetrical and weakly labeled. Our results indicate that chromosome demethylation is associated with each DNA replication and suggest that a passive mechanism predominates during early development.

5-Methylcytosine↗
PubMed1998

Cryopreservation in human assisted reproduction is now routine for embryos but remains a research procedure for oocytes.

Human embryo cryopreservation represents an indispensable extension of in-vitro fertilization (IVF) programmes as long as they are based upon the recovery of a large number of oocytes. The most widely used procedures include the cryopreservation of human zygotes or embryos in early cleavage, using 1,2-propanediol and sucrose as cryoprotectants. Our results over a 10 year period (1986-1995) on 5032 thawed cycles involving 14 222 stored embryos make it possible to appraise the results and the contribution of embryo freezing to assisted reproduction. Embryos survived the freeze-thaw process in 73% of cases leading to 4590 transfers of 2.2 embryos (91% of thawed cycles). The clinical pregnancy rate per transfer was 16%, the live birth rate 12%, and the rate of babies born alive per transferred embryo was 6%. Embryo freezing monitored 10 years later produced an average of 8% of additional births. By then, 86% of stored embryos had been thawed for transfer to patients. Destruction or donation were required for only 8% of all frozen embryos and there was no news from the parental couple in relation to almost 6% of embryos. The fate of the vast majority of embryos was decided during the first 5 years of storage. Blastocyst cryopreservation is making new strides, thanks to co-culture systems and embryo selection. Micromanipulation procedures seem to have little impact on the outcome of embryo freezing. Human oocyte freezing is again clinically applied. Indeed, much of the concern about injuries to the oocyte structures through the freeze-thaw process do not seem to be justified, and the problems with frozen-thawed oocyte fertilization has been overcome using intracytoplasmic sperm injection (ICSI). As long as oocyte in-vitro maturation is not well controlled, better results will probably be obtained with mature oocyte cryopreservation. Emerging methods include the freezing of immature oocytes, follicles and ovarian tissue.

Cryopreservation↗
PubMed1998

Incidence of sex chromosome abnormalities in spermatozoa from patients entering an IVF or ICSI protocol.

OBJECTIVE: The objective of this study was the determination of sex chromosome aneuploidy frequency in spermatozoa from patients included in an in vitro fertilization (IVF) or intra cytoplasmic sperm injection (ICSI) protocol. METHODS: Spermatozoa from nineteen patients, including patients with normal seminal parameters according to World Health Organization (WHO) criteria and patients exhibiting abnormal seminal parameters, were analyzed by dual color fluorescence in situ hybridization (FISH) for aneuploidies of the X and Y chromosomes. Our technique, using only probes for sex chromosomes and not for autosomes, does not discriminate between hyperhaploid and diploid sperm nuclei. The results were analyzed in two different ways: in relation to the semen status, denoted normal or abnormal and with regard to the ability of the sperm to fertilize oocytes when IVF or ICSI was performed. RESULTS: Abnormal semen showed a significant increase in the overall rate of sperm nuclei with XY, XX and YY sex chromosome complements, 1.59% compared to normal semen, 0.78% (p<0.02). Semen shown to be able to fertilize oocytes only by ICSI showed a higher incidence of XY-bearing spermatozoa, 1.26%, compared to semen able to fertilize oocytes by conventional IVF, 0.37% (p<0.001). The incidence of XX-or YY-bearing sperm nuclei was also significantly elevated in the ICSI group (0.25% XX, 0.50% YY) (p<0.02) as compared to the IVF group (0.06% XX, 0.16% YY). CONCLUSIONS: We concluded that infertile men requiring ICSI treatment showed a higher incidence of sex chromosome aneuploidy, due to meiosis I and II nondisjunction, in their spermatozoa as compared to men requiring IVF for reasons of predominantly female infertility.

Aneuploidy↗
PubMed1997

Influence of co-culture with established human endometrial epithelial and stromal cell lines on sperm movement characteristics.

The effects of co-culture of human spermatozoa with human immortalized endometrial cells - epithelial or stromal - on sperm movement characteristics, including hyperactivation, were studied using computer-assisted sperm analysis (CASA). Epithelial and stromal cell types could be separated following 8-10 days of culture of endometrial cells originating from human biopsies. Both cell types were immortalized by the SV 40 large T antigen. Co-incubation of sperm with epithelial and stromal monolayers enhanced the rate of hyperactivation: 24.9% (P <0.05) and 17.8% (P = 0.05) versus 9.5% as control, respectively, whereas the majority of motility parameters remained unchanged. Conditioned media had no effect upon sperm parameters, including hyperactivation. Co-incubation with either monolayer was able to maintain sperm motility over a longer period than incubation in control medium alone. In four patients whose spermatozoa did not exhibit hyperactivation, co-incubation with epithelial cells, but not conditioned medium, allowed normal rates of hyperactivation (range: 6.9-15.6%).

Antigens, Polyomavirus Transforming↗
PubMed1997

The human oocyte. Genetic aspects.

Since the beginning of in vitro fertilization (IVF), basic research has enlightened the field of human reproduction, especially in genetics. Indeed, the contribution of chromosomal anomalies to oocyte disorders and impaired developmental capacities of the embryos is now well known. Among oocytes that failed to fertilize after in vitro insemination, 26.5% were found to be abnormal comprising 13.3% hypohaploidy, 8.1% hyperhaploidy, 1.6% structural anomalies and 3.5% diploidy. The total incidence of abnormalities seems to be correlated to the female status, and was found to be higher in oocytes from women with tubal or unexplained infertility than in those from women whose husband was infertile as a sole cause of couple infertility. Although few oocytes recovered during a natural cycle were studied, gonadotropins widely used to stimulate follicle growth and ovulation do not increase the risk of anomalies. The effect of maternal age on fetal aneuploidy, well documented at birth, has not yet be found unambiguously to be a consequence of an increased rate of aneuploid oocytes. Intra- and extrafollicular influences (perifollicular microvasculature, oxygenation, the presence of residues from cigarette smoke) are able to disturb maturation leading to immaturity and aneuploidy. To conclude, oocyte meiosis is very sensitive to endogenous or exogenous factors, which could lead to chromosomally abnormal oocytes and as a consequence, to abnormal zygotes.

Adult↗
PubMed1997

[Comparative randomized controlled study between human follicle- stimulating hormone (FSH-HP) and human menopausal gonadotropins (hMG) in in vitro fertilization].

We present the results of a prospective randomized trial comparing the issue of IVF-ET and of ICSI when either highly purified human folliculostimulin (FSH-HP) or human menopausal gonadotrophin (hMG) is used. There seems to be a trend to a better rate of ongoing pregnancies when FSH-HP is used although not statistically significant. The study has been stopped due to the lack of hMG.

Adult↗
PubMed1996

Expression of leukaemia inhibitory factor receptor subunits LIFR beta and gp130 in human oocytes and preimplantation embryos.

The expression of both components of the high-affinity leukaemia inhibitory factor receptor, LIFR beta and glycoprotein 130 (gp130), was investigated in human oocytes and individual in-vitro cultured preimplantation embryos by reverse transcription-polymerase chain reaction (RT-PCR). Messenger RNA of both LIFR beta and gp130 was detected in as little as 1/30 and 1/12 sample equivalents of cDNA respectively, in oocytes (n = 4), 4-cell and expanded, blastacyst stage embryos. LIFR beta but not gp130 transcripts were detected at the 2-, 8- and 10-cell stages, and in cavitating and hatched blastocysts. In order to exclude a simian origin of these PCR products resulting from the Vero cell line that was used as a feeder during culture to the blastocyst stage, they were digested with restriction endonucleases Taql (LIFR beta) or Kpnl (gp130). Their human origin was confirmed. The results support an earlier finding of LIFR beta mRNA expression in human blastocysts, and extend these results to earlier stages and oocytes. This is the first report of LIFR beta and gp130 transcription in human oocytes. Taken together these results demonstrate that transcription of LIFR beta and gp130 takes place throughout human preimplantation development, and suggest that functional LIF receptors might be present at these stages. These results further confirm the feasibility of performing mRNA phenotyping of multiple genes with RNA derived from a single preimplantation stage embryo.

Antigens, CD↗
PubMed1996

[Influence of infertility etiology and follicular stimulation protocols on pregnancy outcomes by in vitro fertilization].

During a retrospective study on 152 singles pregnancies obtained by in vitro fecondation at Tenon hospital, and followed in this department between January 1990 and December 1994, we have studied the influence of the IVF (tubal origin, masculine or idiopathic) and the type of stimulation (human menopausal gonadotrophin: hMG or follicle stimulating hormone: FSH) on the weight of the newborn and the pathologies that occurred during the pregnancy. No difference in the antecedents has been found in the different group of patients. This study shows a significative difference (p < 0.001) of the newborn's weight when the indication of IVF is tubal origin or masculine. Also, in all IVF indications, the weight is significantly (p < 0.01) higher after a follicular stimulation by FSH versus hMG. For the pregnancy pathologies, no significative difference has been noted, although arterial hypertension, fetal growth retardation and gestational diabetes appear to be more frequent in the group of women who had stimulation by hMG.

Adult↗
PubMed1996

[Cryopreservation of human embryos after in vitro fertilization: immediate and long-term results].

Between 1990 and 1994, a clinical retrospective study has been carried out at Tenon Hospital on 1200 patients: during this periods. 4845 embryos have been cryopreserved and 31% of the patients had this procedure for their supranumerary embryos. The rate of implantation by embryo was 8% per transfer, comparable to those fresh embryos. Less than 1% of the embryos were abandoned. The contribution of cryopreservation to the IVF program is substantial, increasing pregnancy rate by 10%. Moreover, the rate of multiples pregnancies is significantly lower when implanting frozen thawed embryos (9.6%) vs fresh embryos (p < 0.001). There was no difference between frozen-thawed and fresh embryos, in the implantation rate by embryo, the mean gestational age, and birth weight of singleton, twin and triplet births. From a biological point de vue, a series of 3693 embryos, carried on the same period, in our center has showed that for the success of this procedure, the quality of the embryos was more important, than the duration of the storage. The incidence of major and minor congenital malformations was not different in the two groups of babies (less than 3%). But a retrospective analysis carried out on 84 children, showed 4 major abnormalities, after a follow up of 1 to 9 years. However these anomalies do not seem to have some evident correlation with the cryopreservation procedure; a larger series and a prospective study are needed to get significant results concerning the health of the children born after the procedure of cryopreserved embryos.

Birth Weight↗
PubMed1996

[Oocyte fertilizability and embryo development in poor responders].

Oocyte quality (atresia, immaturity), fertilizability, the incidence of abnormal fertilization (parthenogenesis, triploidy) and embryo development (rate of division and morphology) are similar in poor and normal responders. Only, the small number of available embryos (0.9/patient vs 4.4) penalize these patients.

Adult↗
PubMed1996

[Multiple pregnancies prevention in in vitro fertilization: limiting the number of transferred embryos to two maximum?].

The success of an IVF-programme is mainly linked to the number and quality of embryos transferred as well as women's age, but the incidence of obstetrics complications rises significantly with the number of fetuses. Reducing the number of embryos transferred is therefore recommended in order to avoid the medical, social and financial problems associated with multiple births. Present data suggest that, when at least three embryos of good quality are available, the pregnancy rate already reaches its maximum value when two embryos are transferred. A third one merely increases the number of triple pregnancies. Further studies are needed to conclude, especially in the cases of poor quality embryos.

Adult↗