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F Vialard

Publications and source records attributed to F Vialard.

17 recordsLinked to original sources
PubMed2006

[Long-term effects of environmental endocrine disruptors on male fertility].

Several epidemiologic studies have demonstrated during the last 50 years an increased incidence in testis cancer, male genital tract malformations (cryptorchidism and hypospadias) and a decrease in sperm quality in men. These three pathologies seem to be linked and to belong to the testicular dysgenesis syndrome (TDS). It was suggested that TDS is a consequence of intra-uterine exposure to environmental compounds that disrupt the metabolism of native hormones. Such substances are so called endocrine disruptors (EDs). EDs are present in our daily environment such as food and water (through the use of pesticides), cosmetics, house-care products etc. Experimental models have been carried out to (i) establish a link between EDs exposure and SDT and (ii) identify the mechanisms that are involved in. After a brief definition of EDs and having underlined the importance of the window of exposure to EDs, several mechanisms will be described such as (i) intergenerational transmission (epigenetic), (ii) programmed cell death of testicular cells, (iii) modification of the androgenic signal and (iv) role of the germ cells-nourishing cells. To conclude, we will try to propose some biomarkers that would be useful to identify the potential link between fetal exposure to anti-androgenic EDs and male testicular pathology.

Androgen Antagonists↗
PubMed2006

[Late paternity: spermatogenetic aspects].

The effect of maternal age on the risk of meiotic abnormality is well documented. In contrast little is known about the effect of the paternal age. The question of the risk related to paternal age is raised because of the increased demand of Assisted Reproduction Techniques for older men. This review focuses on the alterations of male semen parameters, testis histology and genetic risks related to age. The motility, vitality and morphology of spermatozoa and semen volume are found decreasing with age. Histomorphometric studies reveal various alterations including a thickening of the basal membrane when spermatogenesis is arrested. The number of germinal and Sertoli cells decreases with increased age. Up to 95 years old, we could find subjects with complete spermatogenesis. Chromosomal analyses in different studies have provided controversial results. Our investigation on subjects aged from 29 to 102 showed that the rate of aneuploidy in the group of aged subjects with preserved spermatogenesis was not statistically different from the young control group. However the incidence of postmeiotic aneuploidy was increased when spermiogenesis had stopped. On the other hand from epidemiological studies, autosomal dominant diseases are known to be associated with paternal age. However, in the case of achondroplasia and Apert syndrome, direct DNA sperm analysis did not reveal significant increase in the mutation frequency with paternal age.

Adult↗
PubMed2006

Evidence of a high proportion of premature unbalanced separation of sister chromatids in the first polar bodies of women of advanced age.

BACKGROUND: Maternal ageing is the only aetiological factor unequivocally linked to aneuploidy. Two mechanisms seem to explain these abnormalities in oocytes: non-disjunction and premature unbalanced separation of sister chromatids (PSSC). Previous studies of unfertilized oocytes argue for a major role of PSSC in the aetiology of aneuploidy for women of advanced age, but in vitro ageing of the oocytes could influence the results. METHODS: Owing to the high prevalence of aneuploidy in women of advanced age, chromosomal screening of the first polar body just before ICSI was offered to women (from 38 years of age) included in an assisted reproduction programme. RESULTS: Among 141 oocytes from 29 women (mean age 40 years and 2 months), 43 (30.5%) were abnormal. Sixty-five abnormalities were found and PSSC was involved in 80% of cases. CONCLUSION: These results are in accordance with previous studies and confirm, in 'fresh' oocytes, the major role of PSSC in the aetiology of aneuploidy in women of advanced age.

Adult↗
PubMed2006

Partial trisomy 20p resulting from recombination of a maternal pericentric inversion: case report of a prenatal diagnosis by chorionic villus sampling.

We report a case of prenatal diagnosis of trisomy 20p resulting from a maternal pericentric inversion. The diagnosis was confirmed on both chorionic villi and amniotic cells. This case underlines the fact that prenatal ultrasound diagnosis of this structural anomaly is difficult. The only early sonographic feature was increased nuchal translucency.

Adult↗
PubMed2005

Dandy-Walker syndrome and corpus callosum agenesis in 5p deletion.

5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy-Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations.

Abortion, Eugenic↗
PubMed2005

[Aging and spermatogenesis: an histologic, cytogenetic and apoptosis study].

OBJECTIVE: The increase of frequency of Assisted Reproductive Techniques (ART) for elder men raises the question of the genetic risk for the offspring. Our aim was to evaluate the influence of ageing on the testicular histology, the aneuploidy rate in testis postmeiotic cells and the DNA fragmentation in sperm. PATIENTS AND METHODS: We performed a histomorphometric study of 36 men aged from 61 to 102 years and 10 young men from 29 to 40 years. The aneuploidy rate was evaluated by fluorescent in situ hybridation (FISH X, Y, 18) and DNA fragmentation in spermatozoa was evaluated by TUNEL. RESULTS: Histomorphometry showed various alterations of testicular histology with age including thickening of the basal membrane when spermatogenesis was arrested. The number of germinal cells and Sertoli cells decreased with age with important individual variations. Nevertheless spermatogenesis could be possible until 95 years. The rate of aneuploidy was not influenced by age when spermatogenesis was complete. However, we observed an increased aneuploidy rate in postmeiotic cells when spermiogenesis was arrested. On the other hand apoptosis was not increased with age. DISCUSSION AND CONCLUSION: Our study confirms that spermatogenesis is possible until a very advanced age (95 years) without any specific chromosome risk. The question of mutagenesis remains to be solved.

Adult↗
PubMed2004

[Prenatal diagnosis of a probable human chimera after fertilization in vitro].

Chimerism is the coexistence of more than one cell line in an individual, due to the fusion of originally separate zygotes. It has been very rarely described in humans. A 36-year-old woman referred for in vitro fertilization (IVF) had three embryos transferred leading to a monofetal pregnancy. Ultrasound examination at 17 weeks showed severe intrauterine growth retardation. Amniocentesis revealed a mixture of 46,XY and 46,XX clones. Histopathologic examination showed a dysmorphic fetus with female phenotype and severe growth retardation. Fusion of two of the three embryos (one male and one female) seems to be the most probable mechanism that could explain both cytogenetic and histopathologic observations.

Adult↗
PubMed2004

[Genomic instability and male infertility].

Knowledge of the human genome has opened the genomic era. The genome instability, its causes and the possible consequences especially about fertility start to be understood. This instability can be observed on chromosome structure but also on genes. Different chromosomes rearrangements involved in infertility including translocations and Y chromosome deletions are described. The Y chromosome is a model of instability, and this instability is the source of its evolution. All those rearrangements are the results of illegitimate recombinations between homologous sequences. On genes we find punctual and dynamic mutations, polymorphisms and epigenetic abnormalities. They all are the results of ADN replication mistakes not corrected by the cellular machine. This machinery is the guardian of the genome integrity and in case of abnormality the programmed cellular death is induced. The knowledge of all these instability mechanisms is essential to appreciate the risk for the offspring after intracytoplasmic sperm injection. Indeed we go round physiological barriers without a complete understanding of the mechanisms involved. Thus, this is an important challenge for research teams but also for all assisted reproduction centers, dealing with ART. Genome is unstable - the very basis of its evolution. But this is also the cause of mistakes with pathological consequences like infertility and mental retardation.

Chromosomes, Human, Y↗
PubMed2003

Possible human chimera detected prenatally after in vitro fertilization: a case report.

BACKGROUND: Chimerism is the coexistence of more than one cell line in an individual, due to the fusion of originally separate zygotes. It has been very rarely described in humans. METHODS: A 36-year-old woman who was referred for in vitro fertilization (IVF) for unexplained infertility had three embryos transferred. RESULTS: Four weeks and five days after the transfer, ultrasound examination detected a single fetus in the uterus. Ultrasound examination at 17 weeks for metrorrhagia showed severe intrauterine growth retardation. Amniocentesis revealed a mixture of 46,XY and 46,XX clones. Histopathologic examination showed a dysmorphic fetus with female phenotype and severe growth retardation. CONCLUSIONS: Although demonstration by fingerprinting has not been possible, fusion of two of the three transferred embryos (one male and one female) seems to be the most probable mechanism that could explain both cytogenetic and histopathologic observations. No chimera has yet been described after IVF. It would be interesting to collect any such observations from other IVF centers.

Abortion, Eugenic↗
PubMed2002

Fetal gender: antenatal discrepancy between phenotype and genotype.

Sexual discrepancy is reported in both 46,XY females and 46,XX males, and most diagnoses of sex reversal are made in the postpubertal period. We report three cases of sexual discrepancy, which were revealed by karyotyping following genetic amniocentesis, chorionic villus sampling and fetal blood sampling. The etiologies of 46,XX male, 45,X male and 46,XY female subjects are reviewed. When sexual discrepancy between fetal karyotype and ultrasonographic fetal phenotype is encountered, sample error and placental mosaicism should be excluded. A detailed fetal ultrasound examination should be performed to check for syndromic gender discrepancy. When repeat karyotyping is indicated, localization of the Sox related Y chromosome gene should be carried out.

Abnormalities, Multiple↗
PubMed2001

Pierre Robin sequence and interstitial deletion 2q32.3-q33.2.

Pierre Robin sequence (PRS) consists of the nonrandom association of micrognathia, cleft palate (CP), and glossoptosis. It also includes respiratory and feeding difficulties that appear to be neurogenic rather than mechanical in causation. Genetic determinants are thought to underlie this functional and morphological entity, based on the existence of Mendelian syndromes with PRS, and the rare observations of familial nonsyndromic PRS, in which some of the affected individuals have isolated CP. We report the association of PRS with deletion 2q32.3-q33.2 due to an unbalanced reciprocal translocation 46,XX, t(2;21), del 2(q32.3q33.2), and we refine the deletion interval with regard to YAC probes and polymorphic DNA markers. The deletion was shown to be flanked by D2S369 (telomeric) and D2S315 (centromeric), thus it maps to a recently determined chromosomal region known to be nonrandomly associated with CP. This observation supports the hypothesis for the genetic bases of nonsyndromic PRS, strengthens its possible genetic association with isolated CP, and provides a candidate PRS locus, in chromosomal region 2q32.3-q33.2.

Chromosome Banding↗
PubMed2000

Overexpression of mSim2 gene in the zona limitans of the diencephalon of segmental trisomy 16 Ts1Cje fetuses, a mouse model for trisomy 21: a novel whole-mount based RNA hybridization study.

Trisomy 21 (Down syndrome) is the most common chromosomal abnormality associated with mental retardation in humans. Sim2, a human homologue of Drosophila sim gene, which acts as a master regulator of the early development of the fly central nervous system midline, is located on chromosome 21, in the Down syndrome critical region, and might therefore be involved in the pathogenesis of some of the morphological features and brain anomalies observed in Down syndrome. We report here the detailed expression pattern of murine mSim2 gene in Ts1Cje mice fetuses, a segmental trisomy 16 mouse model for trisomy 21, and its overexpression in the zona limitans of the diencephalon using a new quantitative method based on the whole-mount RNA hybridization technique.

Animals↗
PubMed2000

Characterization of a novel gene, C21orf6, mapping to a critical region of chromosome 21q22.1 involved in the monosomy 21 phenotype and of its murine ortholog, orf5.

Phenotypic and molecular analyses of patients with partial chromosome 21 monosomy enabled us to define a region, spanning 2.4 Mb between D21S190 and D21S226, associated with arthrogryposis, mental retardation, hypertonia, and several facial anomalies. The markers of the region were used to screen a total human PAC library (Ioannou, RZPD). We isolated 57 PACs, which formed primary contigs. EST clusters (UNIGENE collection) located in a 6-Mb interval, between D21S260 and D21S263, were mapped in individual bacterial clones. We mapped the WI-17843 cluster to the PAC clone J12100, which contains the two anchor markers LB10T and LA329. The open reading frame extends over 960 bp, with three putative start codons. The 1695-bp cDNA containing a polyadenylation signal should correspond to the full-length cDNA. From the genomic sequence, we deduced that the gene contained five exons and that there was a putative promoter sequence upstream from exon 1. In silico screening of DNA databases revealed similarity with a murine EST. The corresponding cDNA (1757 bp) sequence was very similar (>85%) to the human cDNA and had an open reading frame of 876 nucleotides. Somatic hybrid mapping localized the cDNA to mouse chromosome 16. EST analyses and RT-PCR indicated that the third exon in the human gene (exon 2 in the mouse) undergoes alternative splicing. Northern blot hybridization showed that the gene was ubiquitously expressed in humans and mice. The longest mouse clone was used to generate riboprobes, which were hybridized to murine embryos at stages E-9.5, E-10.5, E-12.5, E-13.5, and E-14.5-15, to study the pattern of expression during development. Ubiquitous labeling was observed, with strong signals restricted to limited areas of the telencephalon, the mesencephalon, and the interrhombomeric regions in the central nervous system, and other regions of the body such as the limb buds, branchial arches, and somites.

Amino Acid Sequence↗
PubMed2000

Molecular cytogenetic analysis of a duplication Xp in a female with an abnormal phenotype and random X inactivation.

We describe a female infant with severe abnormal phenotype with a de novo partial duplication of the short arm of the X chromosome. Chromosome painting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) was performed with YAC probes, further delineating the breakpoints. The karyotype was 46, X dup(X)(p11-p21.2). Cytogenetic replication studies showed that the normal and duplicated X chromosomes were randomly inactivated in lymphocytes. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated and they are phenotypically apparently normal relatives of phenotypically abnormal males having dupX. Therefore, in this case, there is functional disomy of Xp11-p21.2 in the cells with an active dup(X), most likely resulting in abnormal clinical findings in the patient.

Adult↗
PubMed2000

[The Human Genome Project and the genetics of infertility].

Nine years after the beginning and five years before the expected end of the Human Genome Project, we will have access in several months to 90% of the human genome sequence. This data certainly opens promising vistas to the better understanding of gametogenesis. This will allow the different types of sterility to be studied through new approaches. The aim of the current review is to describe how the Human Genome Project has proceeded in the last ten years. We also discuss to what extent the knowledge of the human genome sequence is important in understanding the genetic basis of some diseases, such as human infertility. Finally, we review the different methodologies to use this information and their limits.

Ethics↗