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Biomedical subjects

J M Dupont

Publications and source records attributed to J M Dupont.

At least 19 recordsLinked to original sources
PubMed2006

Early and severe amyloidosis in a patient with concurrent familial Mediterranean fever and pseudoxanthoma elasticum.

A young woman patient had early and extensive familial Mediterranean fever (FMF)-related amyloidosis and pseudoxanthoma elasticum (PXE). She had the novel G1042S mutation in the ATP-binding cassette subfamily C member 6 (ABCC6) gene, responsible for PXE, and the mutation M694I in MEFV, the FMF gene. Both mutations were homozygous, in agreement with consanguinity in the parents. ABCC6 deficiency may have increased the severity of amyloidosis by increasing the deposition in target tissues of heparan sulphate, which colocalizes spatially and temporally with amyloid proteins, and/or by decreasing the therapeutic activity of colchicine.

ATP-Binding Cassette Transporters↗
PubMed2004

[Topographical organisation of the chromatin in human interphase nuclei: architecture meets function].

There are an estimated number of 30,000 genes in the human genome, accounting for as few as 5% of the whole DNA content. Determining the exact role of the vast majority of untranscribed DNA is a major goal for upcoming years. Among various evolutionary constrains which could explain the presence of such a quantity of so-called "junk DNA", one hypothesis is the necessary controlled topographical arrangement of the genome during interphase, leading to a non-random, reproducible position of chromosomal regions inside the nucleus. This hypothesis relies on recent progresses in imaging technologies such as fluorescence confocal microscopy, allowing for the first time the identification of each chromosome-specific chromatin during interphase. This review focuses on the past years advances leading to the actual model of chromosome territories in the interphase nucleus.

Cell Nucleus↗
PubMed2002

Pregnancy outcome following prenatal diagnosis of an isodicentric X chromosome: first case report.

An isodicentric X chromosome, idic (X)(q27) was found in a female fetus during cytogenetic studies performed on amniotic cells due to advanced maternal age. No mosaicism was observed. Although segmental inversion duplications have been described for several other chromosomes, isodicentric chromosomes are reported only for gonosomes. Genetic counselling was based on ultrasound findings, cytogenetic replication studies and published cases of X chromosomes duplications ascertained pre- and postnatally. The pregnancy resulted in the birth of a healthy female infant.

Adult↗
PubMed2000

Establishment of the paternal methylation imprint of the human H19 and MEST/PEG1 genes during spermatogenesis.

Parental-specific epigenetic modifications are imprinted on a subset of genes in the mammalian genome during germ cell maturation. However, the precise timing of their establishment remains to be determined. Methylation of CpG dinucleotides has been shown to be a part of the parental imprint. We have examined how the methylation pattern characteristic of the paternal allele in germ cells are established during human spermatogenesis. Two representative imprinted genes, H19 and MEST/PEG1, were studied. The experiments were performed using the bisulphite sequencing method on microdissected individual cells at different stages of male germ cell differentiation. We show that both genes are unmethylated in fetal spermatogonia, suggesting that all pre-existing methylation imprints are already erased by this stage. The MEST/PEG1 gene remains unmethylated at all subsequent post-pubertal stages of spermatogenesis, including mature spermatozoa. The methylation of H19 typical of the paternal allele first appears in a subset of adult spermatogonia and then is maintained in spermatocytes, spermatids and mature spermatozoa. Our results suggest that the methylation imprint inherited from the parents is first erased in the male germ line at an early fetal stage. The paternal-specific imprint is re-established only later, during spermatogonial differentiation in the adult testis.

Adult↗
PubMed1998

Analysis of megakaryocyte growth and development factor (thrombopoietin) effects on blast cell and megakaryocyte growth in myelodysplasia.

Thrombocytopenia is a frequent feature of myelodysplastic syndromes (MDS) that could be improved by the use of recombinant human megakaryocyte growth and development factor (rHuMGDF). Using short-term liquid cultures and progenitor assays, we have found that rHuMGDF stimulated DNA synthesis and potentiated leukemic cluster growth of bone marrow mononuclear cells in 10/38 MDS cases (26%). Cytogenetically malignant colonies were detectable in rHuMGDF-stimulated cultures (n=3) by fluorescence in situ hybridization. rHuMGDF was able to stimulate CFU-MK formation in 45% of the samples tested. Finally, rHuMGDF-induced blast cell proliferation correlated with elevated expression of c-MPL, previously identified as a bad prognosis factor in MDS.

Blast Crisis↗
PubMed1998

Fluorescence in situ hybridization on methylcellulose cultured hematopoietic stem cells from myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are clonal malignancies characterized by peripheral blood pancytopenia and signs of maturation disturbances of one or several cell lineages in bone marrow. MDS present as chimeras associating normal polyclonal and malignant monoclonal progenitors cells in various proportions. Numerous cytogenetic abnormalities have been reported in MDS and can be detected by fluorescence in situ hybridization (FISH) on interphase cells. We have used this technique on methylcellulose cultured hematopoietic progenitors obtained from three patients suffering from MDS and exhibiting informative karyotypic features. Hematopoietic cells were cultured for 14 days, and individual clones (BFU-E, CFU-GM) were picked up and then cytocentrifuged for FISH analysis. We used centromeric probes realized and labeled in our laboratory by PCR to detect aneuploidies for chromosomes 7 and 11 in two patients. Furthermore, we could detect a 5q partial deletion on interphase cells from the third patient using a 5q31 specific probe visualized with the HNPP Fluorescent Detection Set from Boehringer Mannheim. In conclusion, FISH is a helpful method to detect malignant clones in hematopoietic progenitor cultures and hence to study the relative growth of normal vs. leukemic cells in MDS.

Aged↗
PubMed1998

[Genetic basis of Prader-Willi and Angelman syndromes: implications for the biologic diagnosis].

Prader-Willi and Angelman syndromes are two genetic diseases whose clinical diagnosis is often impaired by a wide variability in some clinical findings. New insights in the genetic basis of these disorders allow the proposition of a biological approach to detect almost all Prader-Willi syndrome patients and over 80% of Angelman syndrome patients. Moreover, the results of these tests are indispensable for the evaluation of the recurrence risk.

Algorithms↗
PubMed1998

Polymerase Chain reaction generated probes for fluorescence in situ hybridization.

The extended use of Fish with centromeric probes in many cytogenetic laboratories is often impaired by the cost of this technique. Polymerase Chain Reaction (PCR) constitutes a simple way to generate and label such centromeric probes at low cost. Two types of human DNA source can be used: 1--Somatic hybrid cell lines containing a unique human chromosome. The specific amplification of the human subset of alphoid DNA is realised with a primer pair specific for the consensus region of human alpha satellite sequence. 2--Total Human DNA. This time, a primer pair specific for the alpha satellite DNA of the chromosome of interest must be designed. These probes, labelled during the PCR reaction by direct incorporation of modified dUTP, are actually widely used in our laboratory, alone or mixed with other probes (chromosome painting or locus specific probes).

Cells, Cultured↗
PubMed1997

PEG1 expression in maternal uniparental disomy 7.

PAG1/MEST is an imprinted gene mapping to human chromosome 7q32. In human embryos and placenta, PEG1 is expressed from the paternally derived allele only, while maternal and paternal alleles are transcribed in adult blood lymphocytes. We aimed at investigating the origin of the maternal PEG1 transcript by studying PEG1 mRNA in two maternal uniparental disomy 7 patients suffering from severe pre- and post-natal growth restriction. PEG1 expression has been characterised by RT-PCR from leukocytes RNA using several primer pairs. The distal coding region in PEG1 mRNA could be repeatedly amplified from mUPD patients blood cells, but no amplification could be performed from the first exon, suggesting that the first exon was not a component of the maternal PEG1 transcript. As six independent database sequences showed that exon 2 was exactly joined to a novel sequence unrelated to exon 1 but identical in the common region of the six sequences, we hypothesized that our observation of PEG1 expression in the two maternal uniparental disomy 7 patients could be explained by transcription of the maternal allele from an alternate maternal upstream promoter.

Chromosome Aberrations↗
PubMed1995

Effect of a combination of coumarin derivatives and rutoside on venous and lymphatic circulations during severe constriction of the caudal vena cava in rabbits.

The effect of a coumarin (CAS 91-64-5) derivatives-rutoside (CAS 153-18-4) combination (Esberiven) has been investigated in an in vivo model of venous hind leg stasis elicited by severe constriction of the caudal vena cava in anesthetized rabbits. The vena cava flow is initially reduced by 80% compared to reference values; then, it significantly declines over time. The venous femoral pressure drops as well as the perfusion pressure whereas the peripheral resistance increases. The popliteal lymph flow gradually slows down after the constriction. Moreover, this venous constriction results in a marked reduction of the right ventricular stroke volume responsible for a left ventricle failure and for the exitus of 30% of the rabbits within 1-3 h post-constriction. A 5-day pretreatment (i.v.) with the coumarin derivatives-rutoside combination at a dose of 4 mg of coumarin derivatives + 200 mg of rutoside/rabbit/day increases the lymph flow but does not suppress the mechanically-induced venous flow decrease. The 6th-day treatment (infusion at the respective doses of 5 mg of coumarin derivatives + 250 mg of rutoside/kg or 10 mg of coumarin derivatives + 500 mg of rutoside/kg) induces a dose-related significant increase of both venous and lymph flows and of the femoral pressure. At the same time, the peripheral venous resistance decreases in a dose-response relationship. Furthermore, after administration of coumarin derivatives and rutoside, the right ventricle stroke volume increases and no death occurs.

Animals↗
PubMed1995

[Translocation t(6;9;8)(p23;q34;q22) in acute myeloid leukemia: Contribution of fluorescence in situ hybridization].

A complex translocation involving chromosome 6, 8 and 9 [t(6;9;8)(p23;q34;q22)] associated with other structural and numerical abnormalities was observed on bone marrow karyotype of a woman suffering with acute myeloblastic leukemia (AML2). Fluorescence in situ hybridization agreed with the conventional cytogenetic interpretation by showing that a part of chromosome 6 short arm was inserted on the rearranged chromosome 9 resulting in the t (6;9) usually encountered in AML.

Acute Disease↗
PubMed1990

Effect of halothane on ischemic brain edema.

Halothane anesthesia (2%) given continuously during the ischemic and post-ischemic period in gerbils does not protect against cytotoxic edema but counteracts superimposed vasogenic edema due to the first BBB opening to serum protein during the reflow period, thus allowing specific gravity values at 1-hour reflow to return to initial levels. It seems likely that this effect of halothane is due to a reduction of the hyperemia by halothane, which reduces both blood pressure and brain metabolism. CBF measurements in halothane-treated animals also indicated that intense early postischemic hypoperfusion may well exist in the absence of brain edema.

Animals↗