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Biomedical subjects

C Nogués

Publications and source records attributed to C Nogués.

15 recordsLinked to original sources
PubMed2001

Acrocentric chromosome disomy is increased in spermatozoa from fathers of Turner syndrome patients.

The aim of the present study was to investigate whether there was an increase of aneuploidy in the sperm from fathers of Turner syndrome patients of paternal origin who, in a previous study, showed an elevated incidence of XY meiotic nondisjunction. Sperm disomy frequencies for chromosomes 4, 13, 18, 21 and 22 were assessed by fluorescence in situ hybridisation in four of these individuals. As a group, the Turner syndrome fathers showed a general increase in disomy frequencies for chromosomes 13, 21 and 22, with a statistically significant increase in disomy frequencies for chromosomes 13 and 22 in one of the fathers and for chromosome 21 in two of them. Data from a previous work carried out by us in two fathers of Down syndrome patients of paternal origin also revealed increased sperm disomy frequencies for chromosomes 13, 21 and 22. Pooled as one group, these six fathers of aneuploid offspring of paternal origin had a statistically significant increase in the frequency of nondisjunction for these chromosomes with respect to control individuals. Our findings indicate that there may be an association between fathering aneuploid offspring and increased frequencies of aneuploid spermatozoa. Such increases do not seem to be restricted to the chromosome pair responsible for the aneuploid offspring. Acrocentric chromosomes and other chromosome pairs that usually show only one chiasma during meiosis seem to be more susceptible to malsegregation.

Aneuploidy↗
PubMed2000

Identification of three novel mutations in the insulin receptor gene in type A insulin resistant patients.

Type A insulin resistance syndrome is characterized by the association of ovarian hyperandrogenism, acanthosis nigricans, and severe insulin resistance. We have identified three novel mutant alleles of the insulin receptor gene in 3 patients with type A syndrome, a severe form of insulin resistance. Two of the patients were sisters (A1, A2), 1 of them was a compound heterozygote for a mutation at the 3'-splice acceptor site of intron 21 (AG-->AA), and a missense mutation Val140Leu in exon 2. Her sister was a simple heterozygote for the 3'-splice acceptor mutation. The third patient (A3) was heterozygous for the missense mutation Ala1028Val in exon 17, in the consensus sequence for ATP binding.

Adolescent↗
PubMed1999

Characterization of constitutive heterochromatin in Cebus apella (Cebidae, Primates) and Pan troglodytes (Hominidae, Primates): comparison to human chromosomes.

Using G bands, some homologies between the chromosomes of Cebus apella (CAP) and human chromosomes are difficult to establish. To solve this problem, we analyzed these homologies by fluorescence in situ hybridization using human whole chromosome probes (ZOO-FISH). The results indicated that 1) the human probe for chromosome 2 partially hybridizes with CAP chromosomes 13 and 5, 2) the human probe for chromosome 3 partially hybridizes with CAP chromosomes 18 and 20, 3) the human probe for chromosome 9 partially hybridizes with CAP chromosome 19, and 4) the human probe for chromosome 14 hybridizes with the p-terminal and q-terminal regions of CAP chromosome 6. However, none of the human probes employed hybridized with the heterochromatic regions of CAP chromosomes. For this reason, we characterized the heterochromatic regions of CAP chromosomes and of the chromosomes of Pan troglodytes (PTR), to allow comparison between CAP, PTR, and human chromosomes using in situ digestion of fixed chromosomes with the restriction enzymes AluI, HaeIII, and RsaI and by fluorescent staining with DA/DAPI. The results show that 1) centromeric heterochromatin is heterogeneous in the three species studied and 2) noncentromeric heterochromatin is homogeneous within each of the three species, but is different for each species. Thus, centromeric heterochromatin undergoes a higher degree of variability than noncentromeric heterochromatin.

Animals↗
PubMed1999

Analysis of sex chromosome aneuploidy in sperm from fathers of Turner syndrome patients.

Numerical sex chromosome abnormalities were analyzed in sperm from four fathers of Turner syndrome patients of paternal origin to determine whether there was an increased frequency of sex chromosome aneuploidy and to elucidate whether meiotic malsegregation mechanisms could be involved in the origin of Turner syndrome. Determination of the parental origin of the single X chromosome (maternal in all four cases) and exclusion of X and Y mosaicism were carried out by polymerase chain reaction amplification of five X chromosome polymorphisms and three Y chromosome segments. A total of 45,299 sperm nuclei from Turner fathers and 85,423 sperm nuclei from eight control donors was analyzed by three-color fluorescence in situ hybridization. The four patients showed a significant increase in the percentages of XY sperm (mean 0.22%; range 0.20% to 0.22%) compared with control donors (mean 0.11%; range 0.06% to 0.18%). These results suggest that the four individuals have an increased frequency of nondisjunctional errors in meiosis I, resulting in the production of an increased proportion of XY spermatozoa and of sperm lacking a sex chromosome.

Adult↗
PubMed1999

Paternal sex chromosome aneuploidy as a possible origin of Turner syndrome in monozygotic twins: case report.

The meiotic or mitotic origin of most cases of Turner syndrome remains unknown, due to the difficulty in detecting hidden mosaicisms and to the lack of meiotic segregation studies. We have had the opportunity to study one pair of monozygotic twins concordant for Turner syndrome of paternal origin. The paternal origin of the single X chromosome was determined by polymerase chain reaction (PCR) amplification. No mosaicism was detected for the X or Y chromosome. In this case, a meiotic error during gametogenesis would be a likely origin of X monosomy. To determine if meiotic errors are more frequent in the father of these monozygotic twins concordant for Turner syndrome of paternal origin, molecular studies in spermatozoa were conducted to analyse sex chromosome numerical abnormalities. A total of 12520 sperm nuclei from the twins' father and 85338 sperm nuclei from eight normal donors were analysed using three-colour fluorescent in-situ hybridization. There were significant differences between the twins' father and control donors for XY disomy (0.22 versus 0.11%, P < 0.001) and total sex chromosome disomy (0.38 versus 0.21%, P < 0.001). These results could indicate an increased tendency to meiotic sex chromosome non-disjunction in the father of the Turner twins.

Adolescent↗
PubMed1999

PCR protocol to detect parental origin and hidden mosaicism inSex chromosome aneuploidies.

In this study, we report an accurate method to determine the parental origin of sex chromosome aneuploidies or polyploidies and to detect low percentage mosaicisms. We have amplified by polymerase chain reaction (PCR) five polymorphic markers along the X chromosome (DXS1283E, DYS II, DMD49, AR and DXS52) and three markers along the Y chromosome (SRY, DYZ3 and DYZ1). False-negative results were discarded by the simultaneous amplification of Y markers and of internal controls. We have applied this protocol to a series of 14 Turner syndrome patients with a 45,X karyotype. We have detected sex chromosome mosaicisms in two patients. The parental origin of the syndrome has been determined in the other 12 patients.

Female↗
PubMed1995

Freezing of zona-free mouse embryos: characteristics of the plasma membrane and subsequent development of the embryos.

Frozen-thawed mouse embryos with (+ZP) and without (-ZP) zona pellucida have been studied at the Scanning Electron Microscope (SEM) to determine how the process affects the plasma membrane and the subsequent embryo development. The main difference observed in -ZP embryos immediately after thawing is the abnormal morphology and distribution of microvilli. This could explain the spontaneous separation of blastomeres in -ZP embryos, and the decrease in their survival rate. If thawed -ZP embryos are allowed to recover in culture, their plasma membrane characteristics and survival rate are identical to those of control embryos.

Animals↗
PubMed1995

Cytogenetic studies of oocyte fusion products.

We describe for the first time the cytogenetic characteristics of mouse 'embryos' obtained by oocyte fusion (oocyte fusion products; OFP). Our results indicate that, after fusion, meiosis II is resumed correctly, with extrusion of two haploid polar bodies, and that metaphase synchronisation of the two haploid sets and chromosome segregation during the first cleavage are also normal.

Animals↗
PubMed1994

Ultrastructural studies of early mouse embryos obtained by oocyte fusion.

Oocyte fusion induced by inactivated Sendai virus results in the production of 'zygotes' that are able to undergo the first stages of embryonic development. The oocyte fusion products (OFP) obtained follow a morphological developmental pattern equivalent to that of control embryos, at least up to the 8-cell stage. The percentage of OFP that reach the 8-cell stage is extremely low (3%) compared with control embryos cultured in vitro (95%). On light microscopy, the OFP obtained show morphological characteristics identical to control embryos, although their cell diameters are larger. The cortical reaction, meiotic reactivation, extrusion of second polar bodies and pronucleus formation take place as observed in controls. The ultrastructural characteristics of oocyte fusion products at the 1-, 2-, 4- and 8-cell stages are analogous to those of controls, including the presence of structures related to the activation of the embryo genome. However some differences concerning cell ultrastructure, mainly in the nucleus, are observed and discussed in the text.

Animals↗
PubMed1994

A simple method for processing individual oocytes and embryos for electron microscopy.

A simple method for handling individual specimens that must be processed either for scanning or transmission electron microscopy studies is described. For scanning microscope processing, dehydration is carried out with samples enclosed in small cages made from TAAB capsules in which top and bottom are substituted by plankton nets, and for transmission electron microscopy, samples are preembedded in agarose. This procedure significantly reduces mouth pipetting, dissecting microscope observations, is less labour intensive and, most importantly, reduces sample loss.

Animals↗
PubMed1992

Zona pellucida surface of immature and in vitro matured mouse oocytes: analysis by scanning electron microscopy.

PURPOSE: The aim of this work was to determine the morphology of the zona pellucida surface of immature and in vitro matured mouse oocytes by scanning electron microscopy. For this purpose two groups of immature oocytes (germinal vesicle group and metaphase I group) were studied either before or after in vitro maturation. RESULTS: Before in vitro maturation, the germinal vesicle immature group showed mainly an unstructured zona pellucida surface with smooth cumulus cells. The metaphase I immature group showed a more structured zona pellucida with smooth or blebbing cumulus cells. After in vitro maturation, development of the zona pellucida toward a mature surface, related to the initial degree of oocyte maturity, was observed in both groups. CONCLUSIONS: These observations show a correlation between the morphology of the zona pellucida surface and the degree of oocyte maturity; the in vitro maturation process can give rise to a proper development of this endowment when immature oocytes are used.

Animals↗
PubMed1991

Scanning electron microscope (SEM) study of mouse embryos obtained from isolated blastomeres.

Preimplantation diagnosis and embryo sexing offer great possibilities in the prevention of human diseases and in the field of animal production. These techniques involve blastomere isolation. Isolated blastomeres can grow in culture and develop as whole embryos. In this paper we describe, at the scanning electron microscope level, the characteristics of the plasma membrane surface of isolated blastomeres obtained from mouse embryos at the two-cell stage and of embryos grown to the 2/4- and 4/8-cell stages and compare them to control embryos grown in vitro. According to our results the in vitro manipulation of these embryos does not affect the surface characteristics of the plasma membrane in the early cleavage stages.

Animals↗
PubMed1988

Effects of aging on the zona pellucida surface of mouse oocytes.

In a scanning microscopy study of mouse oocytes from immature, young, and aged females and of oocytes aged in vivo or in vitro, we have observed four types of zona pellucida, which we classify as types A, B, C, and D. Oocyte aging gives rise to a significant increase in predegenerative (type C) oocytes; this type of zona pellucida surface could result from a zona hardening effect and decrease the rate of fertilization of the oocytes affected.

Aging↗