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Biomedical subjects

B Hédon

Publications and source records attributed to B Hédon.

At least 19 recordsLinked to original sources
PubMed2005

Sperm segregation analysis of a (13;22) Robertsonian translocation carrier by FISH: a comparison of locus-specific probe and whole chromosome painting.

BACKGROUND: The t(13;22) Robertsonian translocation constitutes a rare form of rearrangement between acrocentric human chromosomes. Most of the meiotic segregation studies of human Robertsonian translocations have been performed on common t(13;14) and t(14;21) translocations. Analysis of the chromosomal constitution in sperm of Robertsonian translocation carriers is of great interest for assessing the risk of unbalanced forms and adapting genetic counselling. In the present study, we present the first meiotic segregation study of a t(13;22) Robertsonian translocation in human sperm. METHODS: A total of 11 787 sperm nuclei were scored using two distinct FISH labelling techniques, i.e. the locus-specific probes (LSI) method and the whole chromosome painting (WCP) technique. RESULTS: The frequency of normal or balanced sperm resulting from alternate meiotic segregation was 86%. Incidences of unbalanced complements resulting from adjacent segregation modes were 12.79% and 14.36% in LSI and WCP assays, respectively. No significant excess of nullisomy or disomy for the affected chromosomes was observed. CONCLUSIONS: Similar results in segregation were obtained with the two techniques, demonstrating the efficiency of the two strategies for the direct segregation analysis of Roberstsonian translocations. The results obtained indicated a moderate meiotic production of imbalance. This study shows that the rare Robertsonian translocation (13;22) displays a similar distribution of balanced and unbalanced sperm patterns as the common Robertsonian translocations previously studied. This suggests that the behaviour of acrocentric chromosomes was similar in all cases of centric fusion.

Adult↗
PubMed2005

[The cytogenetics of human oocytes: 40 years of progress].

Chromosomal abnormalities account for the majority of pre- and post- implantation embryo wastage in humans. Most of these abnormalities result from maternal meiotic errors, which preferentially occur during the first meiotic division. Consequently, the cytogenetic analysis of human oocytes has then been considered as a highly valuable source of data for the investigation of both the occurrence and the origin of chromosomal abnormalities in human. During the last 4 decades, the cytogenetic analysis of human oocytes has never stopped progressing, according to the advents of new technologies. Both karyotyping and molecular cytogenetic studies have been reported to date, providing a large body of data on the incidence and the distribution of chromosomal abnormalities in human female gametes. However, these studies display a great variability in results, which may be essentially attributable to the limitations of these techniques when applied to human oocytes. The most relevant analysis have led to the estimate that 15-20% of human oocytes present chromosome abnormalities, and they have emphasized the implication of both whole chromosome non-disjunction and chromatid separation in the occurrence of aneuploidy in human oocytes. The effect of advanced maternal age on the incidence of aneuploidy in human oocytes has also been clearly evidenced by recent reports based on large sample of oocytes or polar bodies.

Cell Division↗
PubMed2005

[Ultrasonographical predictive factors of ovarian response to stimulation prior to in vitro fertilization].

OBJECTIVE: Evaluate whether ovarian antral follicles number, ovarian volume and ovarian area are predictive of ovarian response. PATIENTS AND METHODS: Prospective cohort analysis of 41 women with normal basal serum FSH concentration, who were undergoing their IVF cycle. The ovarian antral follicle number, the ovarian volume and area were determined by transvaginal ultrasonography on the third menstrual day for 20 women, and after pituitary suppression for 21 women. The main outcome measures are the number of follicles the day of HCG with a diameter >or=14 mm, the number of oocytes retrieved and the number of embryos. RESULTS: The antral follicle count was significantly correlated to the number of follicles (R=0.7; P<0.001), to the number of oocytes retrieved (R=0.46; P=0.008) and to the number of embryos (R=0.44; P=0.01). The ovarian volume and area was significantly correlated to the number of follicles. DISCUSSION AND CONCLUSION: The total antral follicle number on day 3 has a predictive value for favourable IVF outcome. Because this sonographic count is easy, safe and inexpensive it should be performed prior every IVF cycle.

Adult↗
PubMed2004

One year comparison between two add-back therapies in patients treated with a GnRH agonist for symptomatic endometriosis: a randomized double-blind trial.

BACKGROUND: It has been proposed that hormonal supplementation during prolonged GnRH agonist therapy prevents hypoestrogenic side effects, including bone loss. The optimal combination for long-term treatments with safe metabolic profile remains questionable. A norprogesterone derivative, promegestone, was assessed for the first time in a double-blind trial. METHODS: Seventy-eight patients with endometriosis with rAFS (Revised American Society for Reproductive Medicine) scores of III-IV were randomly assigned to monthly leuprorelin 3.75 mg (1 year) which, after the third injection was used in combination with promegestone 0.5 mg (P) plus either estradiol placebo (PL) or estradiol 2 mg (E) per day. Bone mineral density (BMD) was determined at baseline, 6 and 12 months, and biological and clinical quarterly assessments were performed. Analysis was by the intention to treat method. RESULTS: At month 12, BMD changes from baseline were -6.1 +/- 3.7 and -4.9 +/- 4.0% in the PL-P group, at the spine and hip, respectively. This bone loss was prevented in the E-P group: -1.9 +/- 3.1 and -1.4 +/- 2.3%, respectively (P < 0.0001 inter-group comparisons). The BMD decrease in the E-P group was explained by the changes occurring during the first 6 months of treatment. There was no deleterious change in lipid parameters. Clinical improvement was observed without an inter-group difference. CONCLUSIONS: Estradiol 2 mg and promegestone 0.5 mg per day is an effective and safe add-back therapy, which can be proposed for prolonged leuprorelin treatment over 6 months in severe endometriosis.

Absorptiometry, Photon↗
PubMed2004

[Fetal and umbilical blood cord stem cells: a room for the obstetrician and gynaecologist. Part two].

Stem cells are undifferentiated cells, with the ability to self renew and to differentiate into specialised cells. Besides embryonic stem cells, adult, fetal and umbilical cord blood (UB) stem cells are to be distinguished. These cells are multipotent. Embryonic germ cells (EG) that also are fetal stem cells have proven to be truly pluripotent, since they are able to give derivatives of the three primitive embryonic layers. EG cells have a normal karyotype, and exhibit remarkable long-term proliferative potential. Fetal stem cells and UB cells have already been used in cell therapy trials (e.g., Parkinson's disease, congenital immunodeficiencies and hemopathies). The applications in the field of reproductive biology will lead to a better understanding of genomic imprinting with EG cells. The obstetrician and gynaecologist could act a central part in the production and study of fetal stem cells, using tissues from aborted fetuses or collecting cord blood stem cells.

Abortion, Induced↗
PubMed2004

[Embryonic stem cells: a position for the obstetrician and gynaecologist. Part one].

Stem cells are undifferentiated cells, with the ability to self renew and to differentiate into specialised cells. Embryonic stem cells (ES) have proven to be truly pluripotent, since they are able to give derivatives of the three primitive embryonic layers. Human ES have a normal karyotype, maintain high telomerase activity, and exhibit remarkable long-term proliferative potential, providing the possibility for unlimited expansion in culture. Though human ES cell-based transplantation therapy holds great promises to successfully treat a variety of diseases (e.g., Parkinson's disease, diabetes, and heart failure) many barriers remain in the way of successful clinical trials. Less spectacular, the applications in the field of reproductive biology are also outstanding: stem cell biology will lead us to a better understanding of the cellular and molecular mechanisms of events such as infertility, failure of implantation, genomic imprinting and meiosis. The obstetrician and gynaecologist could act an important part in the production and study of embryonic stem cells. However, these data have to be integrated in the ethical and juridical background of embryonic stem cell research in France.

Cell Differentiation↗
PubMed2003

[Surrogate mothers and ovarian transposition: two attitudes to be considered in young women with cervical carcinoma. A case report].

In cases of cervical cancer, there are 2 major advantages to preserving the ovaries, with or without transposition: hormone function is maintained during subsequent cancer treatment and patient quality of life is improved. We report the first case of pregnancy in a surrogate mother following stimulation of a transposed ovary before irradiation and chemotherapy for a squamous cell carcinoma of the uterine cervix. Because of the wide dissemination of information on the technical progress in this area, patients are now in a position to make therapeutic choices that are no longer guided by strictly medical considerations.

Adult↗
PubMed2003

[Uterine receptivity and embryo implantation. The use of transvaginal scan and Doppler study in its evaluation in ART].

Embryo implantation is a multifactorial event. Biochemical factors are implicated in the quality of the endometrium and in its vascularization. The non-invasive vaginal scan studies the endometrial morphology whereas color and power Doppler studies its vascularity. Through an analysis of the literature, we point out the interest of those techniques in ART.

Embryo Implantation↗
PubMed2003

First preimplantation genetic diagnosis of hereditary retinoblastoma using informative microsatellite markers.

Retinoblastoma is a malignant intra-ocular tumour of developing retina initiated by inactivation of both alleles of the retinoblastoma susceptibility (RB1) gene. This paper reports the first clinical experience of preimplantation genetic diagnosis (PGD) for hereditary retinoblastoma using two highly polymorphic microsatellite markers RB1.20 and D13S284, located within and close to the RB1 gene respectively. Duplex PCRs were tested on more than 300 single lymphocytes from heterozygous individuals at both loci, in order to test the accuracy and reliability of the single-cell protocol. This procedure requires a nested PCR and the analysis of fluorescently labelled PCR products on an automatic DNA sequencer. Amplification efficiency and allele drop-out rates ranged from 96.7 to 98.4%, and 3.7 to 5.4% respectively. This test was found to be accurate and reliable enough to be applied to the study of human blastomeres. Subsequently, this approach was used in a PGD treatment cycle for a couple who already had a child affected with hereditary retinoblastoma and found to be informative for both microsatellite markers.

Adult↗
PubMed2003

Specific detection of deleted and non-deleted dystrophin exons together with gender assignment in preimplantation genetic diagnosis of Duchenne muscular dystrophy.

We have developed a preimplantation genetic diagnosis (PGD) strategy for Duchenne muscular dystrophy (DMD) allowing the simultaneous amplification of four exons (6, 8, 28 and 32) of the dystrophin gene together with ZFX/ZFY genes for gender determination. Preliminary experiments were carried out on 215 single lymphocytes from male and female individuals. Amplification rates ranged from 90.2% for exon 6 to 96.7% for exons 8 and 32. At least four of the five sequences were successfully amplified in 95.8% of single cells, and sexing was possible in 98.5%. This 5-plex assay was found to be robust enough to be used in a PGD clinical procedure and was therefore applied to a family whose female partner was a heterozygous carrier of a large deletion extending from exon 21 to exon 34 of the dystrophin gene. We have thus analysed two exons located in the deleted region of the gene, two non-deleted exons used as intrasample controls, and ZFX/ZFY genes. Cleavage stage embryo biopsy followed by PCR resulted in transfer of three unaffected embryos. The advantage of the present approach is to identify and subsequently transfer unaffected male embryos in addition to female embryos, and is now applicable to all families displaying a deletion involving at least one of these exons.

Dystrophin↗
PubMed2001

Successful in vitro fertilization-surrogate pregnancy in a patient with ovarian transposition who had undergone chemotherapy and pelvic irradiation.

OBJECTIVE: To present a case of IVF-surrogate pregnancy in a patient with ovarian transposition who had undergone chemotherapy and total pelvic irradiation. DESIGN: Case report. SETTING: Teaching hospital. PATIENT(S): A 29-year-old woman who had undergone Wertheim's hysterectomy for a bulky carcinoma of the uterine cervix. INTERVENTION(S): Ovarian transposition before chemotherapy and total pelvic irradiation. Standard IVF treatment, transabdominal oocyte retrieval, and transfer to the surrogate mother. MAIN OUTCOME MEASURE(S): Results of the IVF cycle. RESULT(S): A twin pregnancy at the first cycle and two live newborns. CONCLUSION(S): This is the first reported case of ovulation induction and oocyte retrieval performed on a transposed ovary.

Adult↗
PubMed2000

[Coasting: a response to excessive ovarian stimulation].

The ovarian hyperstimulation treatment increases results of in vitro fertilization. However, the risk of ovarian hyperstimulation syndrome must be carefully evaluated for each patient. An excessive response increases complication and cancellation rates. Coasting could be applied when an excessive response occurred. This method requires stopping gonadotropin administration while GnRH agonist is continued. When the estradiol rate decreases, the hCG administration is allowed. In the literature, results shows adequate pregnancy rates, between 26 and 64%. It seems oocyte quality was not spoiled. However, coasting does not eliminate definitively the risk of ovarian hyperstimulation syndrome. Coasting method could be a safe and efficient method to treat an excessive ovarian response during in vitro fertilization protocol. Pregnancy rates seem to be preserved.

Chorionic Gonadotropin↗