Search PubMed⌕ Search

Biomedical subjects

B Dutrillaux

Publications and source records attributed to B Dutrillaux.

At least 109 records · Page 6Linked to original sources
PubMed1996

Relationship between DNA methylation and gene expression of the HOXB gene cluster in small cell lung cancers.

The expression pattern of the HOXB gene cluster in four xenografted small-cell lung cancers was compared to the methylation of the DNA in the corresponding genomic regions. In 90% (17/19) of the studied cases, the expressed genes were in methylated regions whereas 70% (12/17) of the unexpressed genes were in unmethylated regions. This specific behavior could correspond to a particular gene expression regulation mechanism of the HOX gene network. Since some genes (HOXB2, HOXB4, HOXB7) were always inactive when unmethylated, this unexpected relationship might indicate their key function(s) in the HOX gene network.

Animals↗
PubMed1996

Intracellular pH governs the subcellular distribution of hexokinase in a glioma cell line.

Hexokinase plays a key role in regulating cell energy metabolism. Hexokinase is mainly particulate, bound to the mitochondrial outer membrane in brain and tumour cells. We hypothesized that the intracellular pH (pH1) controls the intracellular distribution of hexokinase. Using the SNB-19 glioma cell line, pH1 variations were imposed by incubating cells in a high-K+ medium at different pH values containing specific ionophores (nigericin and valinomycin), without affecting cell viability. Subcellular fractions of cell homogenates were analysed for hexokinase activity. Imposed pH1 changes were verified microspectrofluorimetrically by using the pH1-sensitive probe SNARF-1-AM (seminaphtho-rhodafluor-1-acetoxymethyl ester). Imposition of an acidic pH1 for 30 min strongly decreased the particulate/total hexokinase ratio, from 63% in the control sample to 31%. Conversely, when a basic pH1, was imposed, the particulate/total hexokinase ratio increased to 80%. The glycolytic parameters, namely lactate/pyruvate ratio, glucose 6-phosphate and ATP levels, were measured concomitantly. Lactate/pyruvate ratio and ATP level were both markedly decreased by acidic pH1 and increased by basic pH1. Conversely, the glucose 6-phosphate level was increased by acidic pH1 and decreased by basic pH1. To demonstrate that the change of hexokinase distribution was not due to altered metabolite levels of glycolysis, a pH1 was imposed for a 5 min incubation time. Modification of the hexokinase distribution was similar to that noted after a 30 min incubation, whereas metabolite levels of glycolysis were not affected. These results provide evidence that the intracellular distribution of hexokinase is highly sensitive to variations of the pH1, and regulates hexokinase activity.

Adenosine Triphosphate↗
PubMed1996

Fine-needle sampling of a case of carcinoma of the breast with neuroendocrine differentiation.

Fine-needle sampling was performed in a woman with a left breast lump. The cytologic diagnosis was consistent with a poorly-differentiated carcinoma. Cytologic features included medium-to-large, round, and spindle-shaped cells with scanty cytoplasm, nuclear molding, and rosette-like structures. Histology revealed an endocrine pattern. Immunohistochemical staining was positive for epithelial and neuroendocrine markers, and electron microscopy showed many small membrane-bound electron-dense granules, confirming the diagnosis of breast carcinoma with neuroendocrine differentiation. DNA flow cytometry and cytogenetic analyses revealed a near-tetraploid tumor.

Biopsy, Needle↗
PubMed1996

DNA methylation of the X chromosomes of the human female: an in situ semi-quantitative analysis.

We present an in situ semi-quantitative analysis of the global DNA methylation of the X chromosomes of the human female using antibodies raised against 5-methylcytosine. The antibodies were revealed by immunofluorescence. Images were recorded by a CCD camera and the difference in intensity of fluorescence between active (early replicating) and inactive (late-replicating) X chromosomes was measured. Global hypomethylation of the late-replicating X chromosomal DNA was observed in three cases of fibroblast primary cultures that were characterized by numerical and structural aberrations of the X chromosomes [46,X,ter rea(X;X), 48,XXXX and 46, X,t(X;15)]. In these cases, the difference between early and late-replicating X chromosomes was significantly greater than the intra-metaphasic variations, measured for a pair of autosomes, that result from experimental procedures. In cells with normal karyotypes, the differences between the two X chromosomes were in the range of experimental variation. These results demonstrated that late replication and facultative heterochromatinization of the inactive X are two processes that are not related to global hypermethylation of the DNA.

5-Methylcytosine↗
PubMed1996

Scanning ion analytical microscopy for high-resolution detection of 5-bromo-2'-deoxyuridine incorporation in metaphase chromosomes.

We investigated the possibilities of using scanning ion analytical microscopy (SIAM) to detect bromine in human metaphase chromosomes. The experiments were performed after incorporation of the thymidine analogue, 5-bromo-2'-deoxyuridine (BrdU), into the DNA or by in situ hybridization of a BrdU-labelled probe for the subcentromeric repeated DNA sequences. The possibilities offered by this microanalytical method were compared with immunofluorescent staining techniques. Well-defined maps of bands containing bromide were obtained with metaphase chromosomes that had incorporated BrdU during the late S-phase. Their patterns were similar to the labelling obtained by immunofluorescence. In addition, SIAM reveals the presence of bromine within constitutive heterochromatic regions in which BrdU is poorly detected by immunofluorescence. The comparison of the 12C14N, 31P and 81Br maps of controls and fluorescence plus Giemsa (FPG) metaphase chromosomes shows the loss of bromide from DNA during this treatment. SIAM emerges as a new powerful microanalytical technology for investigating chromosome structure further.

Bromine↗
PubMed1996

Structural heterogeneity of hsr(11) in the MDA-MB-134 mammary carcinoma cell line.

The MDA-MB-134 cell line was characterized by the presence of two homogeneously staining region (hsr) carrier chromosomes containing sequences from 8p11-p12, 11q13, and 8q24. Using fluorescence in situ hybridization, a detailed study of the organization of this chromosome has been performed. The hsr carrier chromosomes are shown to be identical and to derive from a chromosome 11, on which large segments of the long arm of chromosome 8 are translocated, forming its short arm. The hsr segment is inserted in the long arm, distally to C1NH gene. It is formed by sequences from both chromosomes 8 and 11. For the genes investigated by both methods the number of copies detected by in situ hybridization is compatible with that expected by quantification of Southern blots. In spite of its complexity, a possible mechanism of formation is proposed.

Breast Neoplasms↗
PubMed1996

The accumulation and occurrence of clonal and unstable rearrangements are independent in colorectal cancer cells.

The rates of unstable and clonal rearrangements were compared in a series of colorectal cancers. These tumors were classified in relation to their karyotypes, into monosomic (MT), trisomic (TT), or normal (NT) type. MT have multiple, TT have few, and NT have no clonal, generally unbalanced, chromosome rearrangements. The rates of unstable rearrangements, i.e. chromatid and chromosome breaks, chromatid exchanges, dicentrics, and telomeric associations, were found to be very similar in these tumors, suggesting identical chromosome instability defined as the occurrence of nontransmissible rearrangements at each cell generation. Thus, the chromosomal patterns of these tumors seem to be rather driven by the specific selection of chromosome alterations than by differential rates of occurrence of rearrangements.

Chromosome Aberrations↗
PubMed1996

High glycolysis in gliomas despite low hexokinase transcription and activity correlated to chromosome 10 loss.

Loss of chromosome 10 was observed in 10 out of 12 xenografted glioblastomas studied. Chromosome 10 carries the gene coding the hexokinase type 1 isoenzyme (HK-I), which catalyses the first step of glycolysis, which is essential in brain tissue and glioblastomas. We investigated the relationships between the relative chromosome 10 number, the amount of HK-I mRNA, HK-I activity and its intracellular distribution, and glycolysis-related parameters such as the lactate-pyruvate ratio, lactate dehydrogenase (LDH) and ATP contents. Individual tumour HK-I mRNA amounts were 23-65% lower than that of normal human brain and reflected the relative decrease of chromosome 10 number (alpha < 0.01). Total HK activities of individual glioblastomas varied considerably but were constantly (a mean of seven times) lower than that of normal brain tissue. The mitochondria-bound HK-I fraction of individual tumours was generally over 50%, compared with that of normal brain tissue. As shown by lactate - pyruvate ratios, in all the gliomas, glycolysis was elevated to an average of 3-fold that measured in normal brain. An elevated ATP content was also constantly noted. Adaptation of glioblastoma metabolism to the chromosome 10 loss and to the HK-I transcription unit emphasises the critical role of glycolysis in their survival. We hypothesise that HK-I, the enzyme responsible for initiating glycolysis necessary for brain function, may approach its lowest limit in gliomas, thereby opening therapeutic access to pharmacological anti-metabolites affecting energy metabolism and tumour growth.

Adenosine Triphosphate↗
PubMed1996

Radiation-induced chromosome damage in astronauts' lymphocytes.

The increased number of manned space missions has made it important to estimate the biological risks encountered by astronauts. As they are exposed to cosmic rays, especially ions with high linear energy transfer (LET), it is necessary to estimate the doses they receive. The most sensitive biological dosimetry used is based on the quantification of radiation-induced chromosome damage to human lymphocytes. After the space missions ANTARES (1992) and ALTAIR (1993), we performed cytogenetic analysis of blood samples from seven astronauts who had spent from 2 weeks to 6 months in space. After 2 or 3 weeks, the X-ray equivalent dose was found to be below the cytogenetic detection level of 20 mGy. After 6 months, the biological dose greatly varied among the astronauts, from 95 to 455 mGy equivalent dose. These doses are in the same range as those estimated by physical dosimetry (90 mGy absorbed dose and 180 mSv equivalent dose). Some blood cells exhibited the same cytogenetic pattern as the 'rogue cells' occasionally observed in controls, but with a higher frequency. We suggest that rogue cells might result from irradiation with high-LET particles of cosmic origin. However, the responsibility of such cells for the long-term effects of cosmic irradiation remains unknown and must be investigated.

Astronauts↗
PubMed1996

Constitutive amplification of a zinc finger protein gene in cattle.

The human OZF gene encodes a protein consisting essentially of zinc finger motifs of the Krüppel type. Evolutionary studies revealed amplification of the bovine OZF gene in cattle. Domestic cattle includes two major subspecies: taurine (Bos primigenius taurus) and zebu (B. p. indicus). Amplified sequences were found in both subspecies and mapped to the same locus of chromosome X in band q11. No amplification was found in other bovids and in particular in Bison, the closest related genus to the genus Bos. One copy of the amplified locus was cloned and sequenced. It encodes a protein sharing 95% identity with the human OZF protein. The bovine OZF gene was detected in an additional locus on chromosome 18 in both Bos and Bison, in band q23-24, which is likely to represent the ancestral position of the OZF gene. This is the first evidence of gene amplification in a mammalian species during evolution.

Amino Acid Sequence↗
PubMed1996

Comparative RB1 gene mapping in Homo sapiens, Pithecia pithecia, Macaca sylvana, and Cercopithecus aethiops tantalus.

The chromosomal localization of the gene for retinoblastoma (RB1), which has been mapped to band 13q14 in man, was studied by in situ hybridization on metaphase chromosomes of selected primates, including Pithecia pithecia, Macaca sylvana, and Cercopithecus aethiops tantalus. The results allowed us to determine the position of the bands homologous to human chromosome band 13q14 in these species. Hybridization analysis corroborated the results of previous studies that defined the chromosome homologous to human chromosome 13 (HSA 13) in these species. By comparing RB1 localizations and banding patterns, it is shown that the rearrangement separating HSA 13 from its homologous chromosome in Cercopithecidae is not a pericentric inversion, as suggested by earlier studies. Since the banding pattern and RB1 localization are not changed, the modification of the centromeric index is explained by a centromeric shift or by two inversions, one pericentric and one paracentric.

Animals↗
PubMed1996

Demonstration of homoeologies between human and lemur chromosomes by chromosome painting.

Human-specific probes for chromosomes 3, 7, 9, 14, 19, and 21 were used to paint chromosomes of three lemur species: Eulemur fulvus mayottensis, E. macaco macaco, and Lemur catta. Chromosomes 1 and 3 of E. f. mayottensis are homoeologous to human chromosomes 3, 9, 14, and 21, as previously suggested by chromosome banding. Probes for human chromosomes 7 and 19 produced unexpectedly strong signals in the centromeric regions of all lemur chromosomes, suggesting that sequences homologous to nonrepeated sequences of the human genome have been amplified during the formation of constitutive heterochromatin in lemurs.

Animals↗
PubMed1996

Fine mapping of human HOX gene clusters.

The chromosome localization of human HOX gene clusters has been reinvestigated by fluorescence in situ hybridization (FISH). Three loci were precisely localized in 7p15.3 (HOXA@), 17q21.3 (HOXB@) and 12q13.3 (HOXC@). The localization of HOXD@ was confirmed to 2q31.

Cells, Cultured↗
PubMed1996

Simultaneous obtention of an intense G-banding and chromosome painting.

A method for simultaneously obtaining brilliant G-banding and chromosome painting is described. It is based on a modification of methods enabling the detection of incorporated BrdU by anti-BrdU antibodies conjugated to a fluorochrome. It induces a banding of both painted and non-painted chromosomes. The method was adapted for in situ hybridizations on human and non human (ZOO-FISH) chromosomes.

Animals↗
PubMed1996

Hematopoiesis research in aplastic anaemia induced by accidental protracted radiation.

Over the past few years there have been 2 radiation-related accidents involving a large number of individuals: the April 1986 accident in Chernobyl nuclear power station in the Ukraine and the September 1987 accident in Goiania, Brazil. These 2 radiation-related accidents highlight the major question raised by radiation-induced injury to the haematopoietic system, that is: does a given patient suffer from a reversible or an irreversible haematopoietic stem cell damage? Although about 350 radiation accidents involving several thousand people are known from the literature, in-depth haematopoiesis analyses of individuals after a radiation-related accident have rarely been reported. In this paper we present the case of a young man with radiation-induced aplasia and compare some biological data to those of 16 normal individuals and of 17 patients with acquired aplastic anaemia. Our patient was clinically and biologically (as assessed by long-term bone marrow culture) indistinguishable from patients with idiopathic acquired aplastic anaemia. Furthermore, therapeutic attitudes in this patient are discussed. In-depth study of such radiation-induced aplastic anaemia cases can shed some light in the understanding of this disease and may help in therapeutic decisions.

Adolescent↗
PubMed1995

CD44 expression patterns in breast and colon tumors: a PCR-based study of splice variants.

CD44 cell-surface receptor expresses multiple isoforms, some of which are believed to play a role in tumor growth and metastasis. The CD44 gene is composed of 19 exons, of which 9 (exons 6 to 14) are alternatively spliced to form inclusions in the intervening membrane proximal region. Sequences present in the shortest metastatic variant cloned from a rat metastatic cell line have been shown to correspond to human exons 10 and 11, also called exons v6 and v7. Using RT-PCR, we have addressed in detail the CD44 isoforms produced in human breast and colon tumors. We analyzed 53 breast-tumor- and 58 colon-tumor-related samples as well as 1 benign mastopathy, 1 normal breast, 4 non-invaded lymph nodes and 8 normal colon tissues. All tumors analyzed expressed the hemopoietic CD44 (CD44H) isoform (no alternatively spliced exons added), whereas 81% expressed the CD44E form (addition exons 12, 13 and 14). Furthermore, 85% of tumors presented complex patterns of expression, with an average number of 5 to 6 bands detected. In view of their implication in the metastatic process, we investigated in greater detail the isoforms containing exons 10 and 11 (v6 and v7). Exon 10 was more frequently expressed than exon 11, 80% and 57% of the samples respectively. The great majority of cases showed ladder-like patterns starting from the shortest forms (exons 5-10 or 5-10-11) and larger-molecular-weight bands corresponding predominantly to sequential inclusions of exons from 3' to 5'. Exon-10 and exon-11 variants were also found in one benign mastopathy. The majority of normal tissues (1 breast and 6/8 colon) expressed only the CD44H isoform. These data indicate that expression of metastatic variants is common in human breast and colon tumors and can occur early during cancer progression, as testified by their presence in a benign breast tumor. While expression of exon-10 variants were correlated with presence of distal metastases in colon tumors, exon-11 variants were not (metastatic events were too rare in our breast-tumor series to reach significance). This suggest that exon 10 may correspond to the minimal sequences required to favor metastatic events.

Alternative Splicing↗
PubMed1995

Recurrent cytogenetic alterations of prostate carcinoma and amplification of c-myc or epidermal growth factor receptor in subclones of immortalized PNT1 human prostate epithelial cell line.

To develop an experimental prostate cancer model, we immortalized normal human prostate adult epithelial cells with SV40 large-T antigen. Two sublines were derived in culture, namely PNT1A and PNT1B. They retained the characteristics of prostate epithelial cells, but did not clone in soft agarose. PNT1A occasionally formed undifferentiated adenocarcinoma tumors in nude mice, but only in the presence of matrigel. PNT1A and PNT1B displayed common cytogenetic alterations: a 10q arm deletion, which is a recurrent alteration in prostate carcinoma, chromosome losses and a translocation involving chromosome 5. An extensive study of oncogenic alterations occurring in these cells showed that PNT1A displayed c-myc gene amplification, forming an hsr on chromosome 4, as well as gene amplification, forming an hsr on chromosome 4, as well as c-myc mRNA overexpression, with a faster doubling time (25 hr); moreover, it seemed less sensitive to EGF than PNT1B. PNT1B had a doubling time identical to that of normal cells (48 hr) but displayed EGF receptor gene amplification accompanied by an increased number of EGF binding sites and sensitivity to EGF. Because both cell lines displayed cytogenetic and oncogenic alterations found in prostate cancer, as well as differing malignant potentials, they represent an interesting model for studying the progression of prostate tumors.

Adult↗