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Biomedical subjects

R Pelletier

Publications and source records attributed to R Pelletier.

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

Disomy rates for chromosomes 14 and 21 studied by fluorescent in-situ hybridization in spermatozoa from three men over 60 years of age.

In order to further investigate the paternal-age effect on meiotic non-disjunction rates for the chromosomes 14 and 21, we examined spermatozoa from three men aged > 60, using multicolour fluorescent in-situ hybridization (FISH). More than 10,000 sperm cells were analysed for each of the three subjects (A, B and C), by simultaneously hybridizing two YAC probes specific for chromosomes 14 and 21 respectively using two-colour FISH. The results show that the disomy 21 rates observed in the spermatozoa of two out of the three men aged > 60 years were higher (1.02 and 1.17% respectively) than the rates observed in eight control adults aged < 30 years (mean frequency 0.48%) analysed under similar conditions. These results suggest that there may be a small effect of age on male non-disjunction rates for chromosome 21. However, before any firm conclusions could be drawn, a much bigger sample of older men would have to be compared with a paired control population using the same FISH experimental approach.

Adult↗
PubMed1997

Deletion analysis of ors12, a centromeric, early activated, mammalian origin of DNA replication.

We have generated a panel of deletion mutants of ors12 (812-bp), a mammalian origin of DNA replication previously isolated by nascent strand extrusion from early replicating African Green monkey (CV-1) DNA. The deletion mutants were tested for their replication activity in vivo by the bromodeoxyuridine substitution assay, after transfection into HeLa cells, and in vitro by the Dpnl resistance assay, using extracts from HeLa cells. We identified a 215-bp internal fragment as essential for the autonomous replication activity of ors12. When subcloned into the vector pML2 and similarly tested, this subfragment was capable of autonomous replication in vivo and in vitro. Several repeated sequence motifs are present in this 215-bp fragment, such as TGGG(A) and G(A)AG (repeated four times each); TTTC, AGG, and CTTA (repeated 3 times each); the motifs CACACA and CTCTCT, and two imperfect inverted repeats. 22 and 16 bp long, respectively. The overall sequence of the 215-bp fragment is G/C-rich (50.2%), by comparison to the 186-bp (33.5% G/C-rich) minimal sequence required for the autonomous replication activity of ors8, another functional ors that was similarly isolated and characterized.

Base Sequence↗
PubMed1997

Meiotic behaviour of sex chromosomes investigated by three-colour FISH on 35,142 sperm nuclei from two 47,XYY males.

Meiotic segregation of sex chromosomes from two fertile 47,XYY men was analysed by a three-colour fluorescence in situ hybridisation procedure. This method allows the identification of hyperhaploidies (spermatozoa with 24 chromosomes) and diploidies (spermatozoa with 46 chromosomes), and their meiotic origin (meiosis I or II). Alpha-satellite probes specific for chromosomes X, Y and 1 were observed simultaneously in 35,142 sperm nuclei. For both 47,XYY men (24,315 sperm nuclei analysed from one male and 10,827 from the other one) the sex ratio differs from the expected 1:1 ratio (P < 0.001). The rates of disomic Y, diploid YY and diploid XY spermatozoa were increased for both 47,XYY men compared with control sperm (142,050 sperm nuclei analysed from five control men), whereas the rates of hyperhaploidy XY, disomy X and disomy 1 were not significantly different from those of control sperm. These results support the hypothesis that the extra Y chromosome is lost before meiosis with a proliferative advantage of the resulting 46,XY germ cells. Our observations also suggest that a few primary spermatocytes with two Y chromosomes are able to progress through meiosis and to produce Y-bearing sperm cells. A theoretical pairing of the three gonosomes in primary spermatocytes with an extra sex chromosome, compatible with active spermatogenesis, is proposed.

Adult↗
PubMed1997

Increased aneuploid frequency in spermatozoa from a Hodgkin's disease patient after chemotherapy and radiotherapy.

The frequency of sperm aneuploidy was investigated by fluorescence in situ hybridization (FISH) in a Hodgkin's disease patient shortly after he had received chemotherapy and radiotherapy. Sperm karyotyping of the same patient had previously shown multiple structural abnormalities in most spermatozoa immediately after radiotherapy (day 0), whereas most spermatozoa collected 5 wk later (day 38) exhibited normal metaphase divisions (Rousseaux et al., 1993). Variations in the frequency of aneuploidy could not be detected by sperm karyotyping. Multicolor FISH on interphase spermatozoa revealed an increase in the rate of disomy for chromosomes 1, 6, 11, X, and Y at day 0 as well as at day 38. The high frequency of 24,XY (nondisjunction at meiosis I) and 24,XX (nondisjunction at meiosis II) spermatozoa (8.46% and 1.64% at day 0, respectively) from the Hodgkin's disease patient suggests that both meiosis I and II are affected and that the X chromosome is frequently involved in such malsegregation events. The rate of 46,XY diploidy was also increased in the patient's sperm, up to 0.62% at day 0. While radiotherapy probably affected the postmeiotic cells (spermatids), the patient's cancer and/or chemotherapy are the two major factors that could have affected the dividing spermatogonia and/or spermatocytes, resulting in high aneuploidy rates.

Aneuploidy↗
PubMed1996

Increased incidence of hyperhaploid 24,XY spermatozoa detected by three-colour FISH in a 46,XY/47,XXY male.

Meiotic segregation of gonosomes from a 46,XY/47,XXY male was analysed by a three-colour fluorescence in situ hybridisation (FISH) procedure. This method allows the identification of hyperhaploid spermatozoa (with 24 chromosomes), diploid spermatozoa (with 46 chromosomes) and their meiotic origin (meiosis I or II). Alpha satellite DNA probes specific for chromosomes X, Y and 1 were observed on 27,097 sperm nuclei. The proportions of X- and Y-bearing sperm were estimated to 52.78% and 43.88%, respectively. Disomy (24,XX, 24,YY, 24,X or Y,+1) and diploidy (46,XX, 46,YY, 46,XY) frequencies were close to those obtained from control sperm, whereas the frequency of hyperhaploid 24,XY spermatozoa (2.09%) was significantly increased compared with controls (0.36%). These results support the hypothesis that a few 47,XXY germ cells would be able to complete meiosis and to produce mature spermatozoa.

Adult↗
PubMed1995

Sperm nuclei analysis of a Robertsonian t(14q21q) carrier, by FISH, using three plasmids and two YAC probes.

The meiotic segregation of chromosomes 14 and 21 was analysed in 1116 spermatozoa from an oligoasthenospermic carrier of a Robertsonian translocation t(14q21q), and in 16,392 spermatozoa from a control donor, using two-colour fluorescence in situ hybridisation (FISH). Two YAC probes (cloned in yeast artificial chromosomes) specific for regions on the long arms of these chromosomes were co-hybridised. Of the spermatozoa, 12% were unbalanced, resulting from adjacent segregations. Chromosomes X, Y and 1 were also simultaneously detected in 1335 spermatozoa from the same carrier. Whereas gonosomal disomy rates were not significantly different from those of the control donors, disomy 1 were slightly but significantly increased to 0.7%. The diploidy rate was also slightly increased to approximately 1% in the translocation carrier.

Adult↗
PubMed1995

Human sperm chromosome analysis after microinjection into hamster oocytes.

PURPOSE: Subzonal sperm insemination (SUZI) into hamster oocytes was performed to establish the karyotypes of the fertilizing spermatozoa. METHODS: Spermatozoa from two males with normal semen parameters were microinjected. Of 72 (52 + 20) analyzed sperm chromosome metaphases, only 1 (1.4%) was considered abnormal, showing a structural abnormality. RESULTS: No hyperhaploidy was observed. Rates of sperm chromosomal abnormalities after microinjection were not higher than those reported previously using zona-free egg insemination, suggesting that the SUZI procedure per se does not increase sperm chromosomal abnormalities. CONCLUSIONS: The use of subzonal insemination into hamster oocytes for the study of human sperm chromosomes in males with low sperm counts is discussed.

Animals↗
PubMed1995

Meiotic segregation of the X and Y chromosomes and chromosome 1 analyzed by three-color FISH in human interphase spermatozoa.

Meiotic segregation of the X and Y chromosomes and chromosome 1 was analyzed by three-color fluorescence in situ hybridization (FISH) in 94,575 human interphase spermatozoa from four control subjects. More than 99% of the sperm cells were labeled. The proportions of X- and Y-bearing sperm were estimated to be 49.83% and 48.30%, respectively. The disomy rates were 0.04%, 0.009%, and 0.20% for the X and Y chromosomes and chromosome 1, respectively. Hyperhaploidy with an extra gonosome was found in 0.34% of spermatozoa, due to nondisjunction during meiosis I. The frequency of diploidy was 0.11% at meiosis I and 0.036% at meiosis II. Cohybridization of one autosomal and two gonosomal probes, in three-color FISH in interphase spermatozoa, seems to accurately discriminate diploidies from disomies, as well as the meiotic origin of gonosomal aneuploidies in sperm cells.

DNA Probes↗
PubMed1995

Meiotic segregation in males heterozygote for reciprocal translocations: analysis of sperm nuclei by two and three colour fluorescence in situ hybridization.

The meiotic segregation of chromosomes was analysed in three reciprocal translocation carriers, using FISH on interphase spermatozoa. The segregation pattern was first studied in 27,844 spermatozoa from two siblings carrying the reciprocal translocation t(6;11)(q14;p14). Three centromeric probes, specific for chromosomes 6, 11 and 1, were simultaneously hybridized so that all centric fragments as well as the ploidy of each cell could be determined by three colour FISH. For both subjects, the respective frequencies of alternate/adjacent 1, adjacent 2, 3:1 and 4:0 segregation modes were 88%, 9%, 3+ and < 1%. In another reciprocal translocation t(2;14)(p23.1;q31), a two colour FISH analysis was performed on 4,610 spermatozoa, using a chromosome 2 centromeric probe and a YAC probe located on the centric fragment of chromosome 14. Frequencies of alternate/adjacent 1, adjacent 2, and 3:1 segregations were 89%, 5.2%, and 5.8% respectively. The segregation of chromosomes X, Y and 1 were also analyzed with three colour FISH on the spermatozoa from all three translocation carriers, in order to detect an interchromosomal effect. Aneuploidy rates for the X and Y chromosomes were found to be in the same range in the three translocation carriers and control donors, but disomy 1 rates were slightly increased in the translocation carriers.

Cell Nucleus↗
PubMed1995

Regulation of endothelial VCAM-1 expression in murine cardiac grafts. Roles for TNF and IL4.

The in vivo mechanisms of vascular endothelial activation and VCAM-1 expression were studied in murine heterotopic cardiac grafts. Preliminary studies demonstrated that cardiac allograft endothelia develop reactivity with MECA-32 monoclonal antibody (MAb) and M/K-2 (anti-VCAM-1) MAb within 3 days of transplantation, whereas cardiac isografts develop MECA-32 reactivity but no M/K-2 reactivity. Additional studies demonstrated that a single treatment of cardiac isograft recipients with the anti-CD3 MAb 145-2C11 induces VCAM-1 expression on isograft microvascular endothelia within 24 hours. We have used this experimental system to identify the cytokines responsible for expression of VCAM-1 and MECA-32 MAb reactivity on graft vascular endothelia. We report that the expression of VCAM-1 on isograft endothelia that was induced with anti-CD3 MAb was blocked by simultaneous treatment with either pentoxifylline, soluble tumor necrosis factor (TNF) receptor (TNFR-Fc), anti-IL4 MAb, or soluble IL4R, but not by anti-IFN-gamma MAb. Alternatively, a similar pattern of isograft endothelial VCAM-1 expression was stimulated in the absence of anti-CD3 MAbs with a single injection of human recombinant TNF-alpha, or with recombinant murine IL4 provided as IL4/anti-IL4 MAb complexes. In addition, the IL4-induced VCAM-1 expression was completely blocked by a single intravenous treatment of the isograft recipients with TNFR:Fc. This suggests that high concentrations of TNF-alpha can stimulate endothelial VCAM-1 expression, but these concentrations are apparently not achieved in cardiac isografts. In the absence of an inducing agent such as anti-CD3 MAb, the stimulation of VCAM-1 expression with exogenous IL4 may reflect functional interaction between endogenous TNF and exogenous IL4, as suggested by the blocking experiments with TNFR:Fc. Although cardiac isograft endothelia normally develop reactivity with MECA-32 MAb within 3 days of transplantation, treatment of cardiac isograft recipients with anti-CD3 MAb accelerated MECA-32 reactivity to within 24 hours of transplantation. This accelerated expression can be experimentally manipulated in the same way as M/K-2 reactivity, suggesting that similar mechanisms may control the development of these two inflammatory endothelial phenotypical markers, despite their differential expression in cardiac isografts and allografts.

Animals↗
PubMed1994

Male meiotic segregation of gonosomes analysed by two colour FISH in human interphase spermatozoa.

Human meiotic segregation of X and Y chromosomes was simultaneously analysed by dual fluorescence in situ hybridization (FISH) on 10,638 interphase spermatozoa from the same donor. A modified method for sperm decondensation ensured access of both X and Y probes to the sperm chromatin and a 99% hybridization efficiency. Expected sex ratios were obtained (49.30% haploidy X and 49.22% haploidy Y). The frequencies of meiotic II non-disjunctions for X and Y chromosomes (0.05%) were similar to those observed in sperm karyotypes after heterospecific fertilization of hamster eggs. In contrast, the frequency of XY bearing cells was significantly higher (0.42%). However, XY cells detected by FISH could either be diploid somatic cells, diploid germinal cells or hyperhaploid XY spermatozoa, the latter resulting from meiotic I non-disjunctions.

Chromosome Aberrations↗
PubMed1994

Achievement of meiosis in XXY germ cells: study of 543 sperm karyotypes from an XY/XXY mosaic patient.

Human sperm chromosomes from a 46,XY/47,XXY male were obtained using the technique of in vitro penetration of zona-free hamster eggs. The analysis of 543 sperm complements shows a significantly increased incidence (0.9%) of hyperhaploid gonosomal 24,XY sets, with a lack of the expected corresponding gonosomal hypohaploidies, and a normal rate of autosomal non-disjunctions. These results support the suggestion that 47,XXY cells are able to go through meiosis and to form spermatozoa. Only 24,XY sperm chromosomal constitutions were observed suggesting a preferential pairing of homologous sex chromosomes in 47,XXY spermatocytes.

Adult↗
PubMed1994

Adolescent running away behavior: active or passive avoidance?

One hundred seventeen boys and 149 girls participated in a study investigating whether adolescent running away behavior is an expression of passive (internalization) or active (externalization) avoidance. Results of principal component analyses indicate that boys' running away behavior is associated with passive avoidance and internalization, whereas for girls the behavior reflects a mixed pattern simultaneously expressing withdrawal and overt deviancy.

Adolescent↗
PubMed1990

The empirical testing of Harter's self-concept matrix on female adult students.

This research aimed at testing an hypothetical matrix to be used for the study of self-concept development within a life-span perspective. Following data categorization collected from 111 female university students, a significant relationship was found between structural levels and content dimensions, demonstrating a linear form of development. Also several content dimensions were often used in subjects' self-definitions, illustrating the multidimensional aspect of such development in adults.

Adult↗
PubMed1990

[Chromosome abnormalities of human gametes].

Human newborns carrying chromosomal abnormalities are the survivors of a considerably larger cohort of affected conceptions. A direct cytogenetic study of these conceptuses would imply their destruction. Moreover, the ability to determine the parental origin of an additional or missing chromosome is limited from a methodological point of view. The cytogenetic study of human gametes provides information on these mechanisms. Several large-scale studies on sperm complements of normal men give an estimated abnormality rate of 10%. Our results concerning four carriers of reciprocal translocations show no evidence for a selection against abnormal sperm. Since about 30% of the recovered eggs fail to become fertilized in IVF programs, human oocytes have become available for large cytogenetic studies. Analysis of oocytes II provides information on the first meiotic non-disjunction rate. In our sample of 405 karyotypes, the rate of aneuploidy was 27%. No relationship was established between this frequency and the mode of stimulation of ovulation. No increase was observed with maternal aging.

Adult↗