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Biomedical subjects

V C Nguyen

Publications and source records attributed to V C Nguyen.

At least 19 recordsLinked to original sources
PubMed1997

Emergence and scattering of multiple neurofibromatosis (NF1)-related sequences during hominoid evolution suggest a process of pericentromeric interchromosomal transposition.

Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase activating protein family and is considered to be a tumor suppressor gene. Its very high rate of de novo mutation in humans led us to study a specific feature of this gene: the presence of numerous NF1-related sequences. According to our results, the human genome contains at least 11 NF1-related sequences, nine of which are scattered near centromeric sequences of seven different chromosomes. These NF1-related sequences, whose extent is quite varied according to loci, are unprocessed copies of the NF1 gene, and bear numerous mutations. A phylogenetic analysis of the six largest sequences indicates that they are all derived from a common ancestor, which would have appeared 22-33 million years ago, and was subsequently duplicated several times during hominoid evolution. The most recent duplication and interchromosomal transposition occurred in the last million years suggesting that the process could still be ongoing. Intriguing similarities between the evolution of alpha-satellite DNA and NF1-related sequences suggest the involvement of a common genetic mechanism for the generation and pericentric spreading of these NF1 partial copies.

Animals↗
PubMed1997

Chromosomal mapping and expression of the human cyr61 gene in tumour cells from the nervous system.

AIMS: To characterise the human cyr61 gene (cyr61H) and determine its chromosomal locality. To compare expression of cyr61H in human tumour cell lines with that of two other structurally related genes, novH (nephroblastoma overexpressed gene) and CTGF (connective tissue growth factor), that are likely to play a role in the control of cell proliferation and differentiation. METHODS: To isolate the human cyr61 gene, placental genomic and HeLa cDNA libraries were screened with murine cyr61 cDNA. The nucleotide sequence of the complete cyr61H cDNA was established. Both Southern blotting of a panel of somatic cell hybrids and in situ hybridisation on chromosomes were performed to map the cyr61H gene. Expression of cyr61H, novH, CTGF, and novH was analysed by northern blotting in both human neuroblastomas and glioblastoma cell lines. RESULTS: Genomic and cDNA clones encompassing the cyr61H gene were isolated and characterised. Comparison of mouse and human cyr61 sequences indicated that their genomic organisation is highly conserved. Alignment of coding sequences highlighted the conservation of cyr61 regions that might be critical for its biological function. The data showed that the cyr61H gene is assigned to chromosome 1p22.3 and that different levels of cyr61H, CTGF, and novH mRNA have been detected in several human tumour cell lines derived from the nervous system. CONCLUSIONS: The human cyr61 gene belongs to an emerging family of genes including CTGF/fisp12 and nov. The murine cyr61 encodes an extracellular cysteine rich protein that exhibits chemotactic activity, promotes attachment and spreading of cells, and potentiates the mitogenic effect of growth factors. Assignment of the cyr61H gene to chromosome 1p22.3 will allow studies to determine whether human pathologies derived from the nervous system or from other tissues are associated with chromosomal abnormalities involving this region. Although the coding regions of cyr61H, CTGF, and novH are highly homologous, a growing body of evidence suggests that expression of these genes is regulated differentially, and that a balance between expression of these genes might represent a key element in determining the stage of differentiation and/or the malignant potential of tumour cells.

Animals↗
PubMed1997

Effect of long-term alcohol administration on bone metabolism in rats.

The purpose of this study was to investigate the effects of different degrees of alcohol ingestion on bone strength and mineral density. Three different groups of growing female rats were administered different doses of an alcohol-water solution for a period of 6 months. These three groups were divided into: 1) the control group, which was only given water; 2) the moderate group, which was given 5% ethanol solution for only 2 h per day; and 3) the excess group, which was given only 5% ethanol solution for 163 days. This ethanol consumption induced no detrimental effect on biochemical parameters including liver function. The moderate group showed significantly higher (p < 0.05) levels of proximal metaphysis as compared to the control group, while there was no difference between the excess group and the control group. Similarly, in comparison to the control group, the moderate group exhibited a significant increase (p < 0.001) in bone mechanical strength, while the excess group showed either the same or decreased bone stiffness. These results indicate that alcohol intake has both beneficial and hindering effects on the skeleton, depending on the concentration and frequency of ethanol intake.

Absorptiometry, Photon↗
PubMed1996

Assignment of the NTRK4 (trkE) gene to chromosome 6p21.

Reverse transcriptase-polymerase chain reactions using foetal brain RNA with reverse and forward primers of the first, second and third NTRK4 region allowed us to obtain three amplified NTRK4 fragments. The specificity of amplified fragments was checked by digestion with restriction endonucleases AvrII, HindIII and PspII for the first, second and third regions, respectively. Each restriction site was specific for each amplified fragment. The fragment of the NTRK4 first region was also sequenced and the sequence determined was identical to the human NTRK4 sequence. The three amplified fragments were cloned in pBS. For the Southern technique, plasmid pBS-NTRK4a (with an insert of 1052 bp) detected a human 9-kb HindIII sequence which was localised unambiguously on chromosome 6. For fluorescence in situ hybridisation, the three plasmids, pBS-NTRK4a, pBS-NTRK4b (insert 924 bp) and pBS-NTRK4c (insert 1114 bp) were pooled and used as a probe. This NTRK4 probe was localised on 6p21. Of 50 metaphases analysed, 49 contained twin spot signals on both sister chromatids.

Base Sequence↗
PubMed1996

Dual localization of the human gene encoding hnRNP I/PTB protein to chromosomes 19p13.3 and 14q23.

A cDNA probe representative of the human hnRNP I/PTB gene was used to perform fluorescence in situ hybridization (FISH) on metaphases of human chromosomes. A new localization was found on band 19p13.3 in addition to the previously reported localization to band 14q23. Identical results were obtained when FISH analysis was repeated with probes covering different parts of the hnRNP I cDNA clone. This supported the notion that most, if not all, of the sequences of the different parts of this clone are present on both chromosomes. Moreover, Southern blot analysis of DNAs from interspecies somatic hybrids containing chromosomes 19 and 14 revealed that the whole hnRNP I cDNA probe generated very similar patterns in each hybrid DNA. These data suggest that two closely related copies of the hnRNP I gene exist in the human genome.

Blotting, Southern↗
PubMed1996

MDM2 amplification in a primary alveolar rhabdomyosarcoma displaying a t(2;13)(q35;q14).

This report describes a case of rhabdomyosarcoma associated with a 2;13 translocation and multiple double minute chromosomes. The origin of the amplified DNA was identified using comparative genomic hybridization, which pinpointed a unique spot at 12q13-->q14. Band 12q13 has been shown to contain several genes that are occasionally amplified in other sarcomas. Fluorescene in situ hybridization to tumor metaphases with probes specific for this region indicated that the double minutes contained the MDM2 gene but not the CDK4 gene. MDM2 amplification was further quantified by Southern hybridization, which showed a mean value of 25 copies per haploid genome. This is the first example of MDM2 amplification in a rhabdomyosarcoma.

Adolescent↗
PubMed1996

Desmutagenicity of soybean after heating.

The mutagenicity and desmutagenicity of extracts of soybeans heated at 225 +/- 5 degrees C were investigated by the Ames test. The soybeans were refluxed in water, methanol, or diethylether for 2 h. The aqueous and methanol extracts (2-4 mg/plate) of the heated soybeans exhibited strong desmutagenic activity of 43-92% against heterocyclic amines (Trp-P-1. Glu-P-2, IQ, MeIQx. PhIP), while no mutagenicity was observed. The desmutagenicity of the heated soybean extracts remained even after denaturation by 0.1 N HCl in vitro and absorption by the rat small intestine. The desmutagenic mechanism for heated soybeans was evaluated, and it was verified that the soybean extract exhibited its desmutagenicity by blocking the mutagenicity of activated Trp-P-1, and not by inhibiting the S9 enzyme system.

Animals↗
PubMed1995

The MUC5AC gene: RFLP analysis with the Jer58 probe.

We have recently obtained evidence that the locus corresponding to three groups of partial tracheobronchial cDNAs (A = Jer47, B = Jer57, C = Jer58) which mapped to chromosome 11p15 and was given the symbol MUC5 corresponds to two distinct genes which we have provisionally called MUC5B and MUC5AC. Here we describe the detection, using the Jer58 probe, which contains a 24-bp tandem repeat, of polymorphism in the MUC5AC gene with seven different restriction enzymes.

Bronchi↗
PubMed1995

A Tsp509I variant in exon 13 of the neurofibromatosis type 1 (NF1) gene allows the identification of both alleles at the mRNA level.

We describe here a new sequence variant occurring in the coding region of the neurofibromatosis (NF1) gene (exon 13). This exonic polymorphism can be directly investigated by simple restriction enzyme digestion of RT-PCR (reverse transcription-polymerase chain reaction) products, making it a powerful tool for examining allele-specific mRNA expression levels.

Alleles↗
PubMed1995

Human gp130 transducer chain gene (IL6ST) is localized to chromosome band 5q11 and possesses a pseudogene on chromosome band 17p11.

Human gp130 (IL6ST) is one of the most widely used chains of the cytokine receptor family. Indeed, it is involved in signal transduction of interleukin-6, interleukin-11, leukemia inhibitory factor, oncostatin M, and ciliary neurotrophic factor. In a previous report, IL6ST was assigned to chromosomes 5 and 17. Here we specify the chromosomal sublocalization of IL6ST and show that the sequence detected on 17p11 corresponds, in fact, to a nontranscribed pseudogene, whereas the active gene is located at chromosome band 5q11.

Antigens, CD↗
PubMed1995

A new hybrid cell line containing only human chromosome 15 selected through fluorescence in situ hybridization and characterized by Alu-PCR amplification of the human DNA.

Human Cot1 DNA directly labeled with dUTP-fluorochromes (FITC, Rhodamin) and used as a probe, allowed rapid detection of one or a few human chromosomes in human-hamster hybrid cells by in situ hybridization (FISH). A hybrid cell line containing only a human acrocentric chromosome was isolated (CH35B2D). The DNA from this hybrid was used for PCR amplification with a single Alu (A33) primer. After agarose gel electrophoresis, a continuum of intense bands of between 400-700 bp was observed with A33-PCR products. No amplified product was visible with hamster DNA. FISH on normal human metaphases of biotinylated Alu-PCR products obtained with Alu A33 and compétition with human Cot1 DNA showed decoration, with high specificity for chromosome 15. It was identified after R banding obtained with PI or DAPI in an antifade adjusted to pH11 with NaOH. Under the applied conditions, the Alu (A33) products are expected to be useful for characterization, by specific decoration of chromosome 15 aberrations in pathological cells. CH35B2D could be employed for functional studies of genes located on chromosome 15.

Animals↗
PubMed1994

Structural organization and chromosomal localization of a human gene (HIP/PAP) encoding a C-type lectin overexpressed in primary liver cancer.

We previously identified, through differential screening of a human primary liver cancer library, a novel gene (named HIP) the expression of which is markedly increased in 25% of human primary liver cancers. HIP mRNA expression is tissue specific since it is restricted to pancreas and small intestine. HIP protein consists in a signal peptide linked to a carbohydrate-recognition domain (CRD), typical of C-type lectins without other binding domains. We have proposed that HIP and related proteins belong to a new family of C-type lectins. Drickamer [Drickamer, K. (1993) Curr. Opin. Struct. Biol. 3,393-400] included this group of proteins in his classification of C-type lectins as the free CRD (group VII) lectins. In the present report we describe the genomic organization and the chromosomal localization of HIP. We have shown that HIP is in fact the pancreatitis-associated protein (PAP) and provided a phylogenetic analysis of the free CRD lectins. Furthermore, the analysis of HIP/PAP gene indicates that the HIP/PAP CRD is encoded by four exons, a pattern shared with all members of this group of proteins. This common intron-exon organization indicates an ancient divergence of the free CRD-lectin group from other groups of C-type lectins. We provide evidence for the localization of HIP/PAP on chromosome 2, suggesting previous duplication of HIP/PAP and the related reg I alpha and reg I beta genes from the same ancestral gene. Finally, the sequence of the 5' upstream region of the HIP gene shows several potential regulatory elements which might account for the enhanced expression of the gene during pancreatic inflammation and liver carcinogenesis.

Amino Acid Sequence↗
PubMed1994

Assignment of the human 8.5 H gene to chromosome 5, region 5q35.

The human 8.5 H probe was isolated from a human cerebellum cDNA library with a probe corresponding to the coding region of the murine 8.5 M cDNA. This cDNA isolated from a murine cDNA library constructed from newborn cerebral hemispheres was selected because of its strong expression in embryonic neurons. Consequently the corresponding human gene could be a candidate for hereditary neurodegenerative diseases. The human 8.5 H gene was assigned by somatic hybrid analysis to chromosome 5; this chromosome contains the gene(s) for spinal muscular atrophy (SMA), a group of heritable degenerative diseases that selectively affect the anterior horn motor neuron of the spinal cord. The localization by in situ hybridization of 8.5 H on 5q35 excluded the possibility that this gene is identical to SMA. The SMA gene(s) was (were) known, from linkage analysis, to be in a region (5q11.2-q13.3) very distant from 5q35.

Animals↗
PubMed1993

Isolation of kidney complementary DNAs down-expressed in Wilms' tumor by a subtractive hybridization approach.

We applied a subtractive hybridization approach to isolate genes differentially expressed between mature kidney and Wilms' tumor. We constructed a complementary DNA library from a total mature kidney complementary DNA subtracted by an excess of mRNA from a Wilms' tumor, WAGR4, with a germline deletion of 11p13 and a somatic loss of alleles at 11p15. Six clones presenting a differential pattern of expression, positive with mRNA from the mature kidney and negative with mRNA from the Wilms' tumor WAGR4, were characterized. Among these clones were two as yet unknown expressed sequences (D11S877E and D15S109E) and four sequences from known genes: renal dipeptidase (DPEP1), alpha B-crystallin (CRYA2), uromodulin (UMOD), and plasma glutathione peroxidase (GPX2). The different patterns of expression of these genes in 11 Wilms' tumors, whether or not they are hereditary, reflect the well-documented pathogenetic heterogeneity for Wilms' tumors. We propose that these clones could be helpful for an improved histological characterization of Wilms' tumors.

Adult↗
PubMed1993

Cloning of a breakpoint cluster region at band 3q27 involved in human non-Hodgkin's lymphoma.

In a previous cytogenetic analysis, we showed the recurrence of translocations involving band 3q27 and immunoglobulin gene regions in 20 out of 319 patients with non-Hodgkin's lymphoma (NHL). We report here the molecular cloning of the translocation breakpoint from tumor cells of a patient (LAR) with t(3;14)(q27;q32) and the isolation of DNA probes which identify a major translocation cluster region (MTC) at band 3q27. A DNA library from LAR tumor cells was screened with a JH probe and several clones were identified corresponding either to a somatic rearrangement of JGH genes (V4-D2-J6-C mu clonal rearrangement) or to the t(3;14). Analysis of the t(3;14) breakpoint showed that chromosome 3 material was translocated to an inverted 14q32 VH-containing fragment which was itself translocated to the J3 gene. Chromosome 3-assigned probes were used to investigate local DNA rearrangements in a series of NHL with 3q27 translocations. Rearrangements were detected in 13 of 17 patients including 9 of 11 with t(3;14)(q27;q32), 1 of 2 with t(2;3)(p12;q27), 1 of 2 with t(3;22)(q27;q11), and 2 of 2 NHL with translocations not involving an IG gene, namely, t(3;4)(q27;p11) and t(3;7)(q27;p12). The finding of this MTC should be useful for diagnostic and prognostic studies and for the identification of a novel oncogene at band 3q27 involved in the development of B cell NHL.

Base Sequence↗
PubMed1993

A human pseudoautosomal gene encodes the ANT3 ADP/ATP translocase and escapes X-inactivation.

We report that the human ANT3 ADP/ATP translocase gene is a pseudoautosomal gene located proximal to the GM-CSF receptor alpha chain gene (CSF2RA). An ANT3-homologous locus, likely corresponding to a pseudogene, maps to chromosome 9. The ANT3 gene is transcribed from the centromere to the telomere and contains in its first intron a CpG island mapped 1300 kb from the telomere. This gene is transcribed from the Y chromosome and from the active and inactive X chromosomes. This gene thus escapes X-inactivation as predicted for genes belonging to the pseudoautosomal region.

Aneuploidy↗