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V David

Publications and source records attributed to V David.

At least 73 records · Page 4Linked to original sources
PubMed1996

Structural analysis of the HLA-A/HLA-F subregion: precise localization of two new multigene families closely associated with the HLA class I sequences.

Positional cloning strategies for the hemochromatosis gene have previously concentrated on a target area restricted to a maximum genomic expanse of 400 kb around the HLA-A and HLA-F loci. Recently, the candidate region has been extended to 2-3 Mb on the distal side of the MHC. In this study, 10 coding sequences [hemochromatosis candidate genes (HCG) I to X] were isolated by cDNA selection using YACs covering the HLA-A/HLA-F subregion. Two of these (HCG II and HCG IV) belong to multigene families, as well as other sequences already described in this region, i.e., P5, pMC 6.7, and HLA class 1. Fingerprinting of the four YACs overlapping the region was performed and allowed partial localization of the different multigene family sequences on each YAC without defining their exact positions. Fingerprinting on cosmids isolated from the ICRF chromosome 6-specific cosmid library allowed more precise localization of the redundant sequences in all of the multigene families and revealed their apparent organization in clusters. Further examination of these intertwined sequences demonstrated that this structural organization resulted from a succession of complex phenomena, including duplications and contractions. This study presents a precise description of the structural organization of the HLA-A/HLA-F region and a determination of the sequences involved in the megabase size polymorphism observed among the A3, A24, and A31 haplotypes.

Cell Line↗
PubMed1996

Linkage disequilibrium and extended haplotypes in the HLA-A to D6S105 region: implications for mapping the hemochromatosis gene (HFE).

The hemochromatosis gene (HFE) maps to 6p21.3, in close linkage with the HLA Class I genes. Linkage disequilibrium (LD) studies were designed to narrow down the most likely candidate region for HFE, as an alternative to traditional linkage analysis. However, both the HLA-A and D6S105 subregions, which are situated 2-3 cM and approximately 3 Mb apart, have been suggested to contain HFE. The present report extends our previous study based upon the analysis of a large number of HFE and normal chromosomes from 66 families of Breton ancestry. In addition to the previously used RFLP markers spanning the 400-kb surrounding HLA-A, we examined three microsatellites: D6S510, HLA-F, and D6S105. Our combined data not only confirm a peak of LD at D6S105, but also reveal a complex pattern of LD over the i82 to D6S105 interval. Within our ethnically well-defined population of Brittany, the association of HFE with D6S105 is as great as that with HLA-A, while the internal markers display a lower LD. Fine haplotype analysis enabled us to identify two categories of haplotypes segregating with HFE. In contrast to the vast majority of normal haplotypes, 50% of HFE haplotypes are completely conserved over the HLA-A to D6S105 interval. These haplotypes could have been conserved through recombination suppression, selective forces and/or other evolutionary factors. This particular haplotypic configuration might account for the apparent inconsistencies between genetic linkage and LD data, and additionally greatly complicates positional cloning of HFE through disequilibrium mapping.

Base Sequence↗
PubMed1996

Physical map of the HLA-A/HLA-F subregion and identification of two new coding sequences.

As part of an effort to characterize the hemochromatosis gene, we selected three non-chimeric yeast artificial chromosomes (YACs) overlapping with the YAC B30 previously described and forming an 800 kilobase contig covering the HLA-A/HLA-F region. The precise physical map of these YACs and of the corresponding genomic region were established. Nine concentrated sites of CpG cutter elements, potentially HTF islands, were mapped. In addition, several probes have been generated as tools for mapping and examining transcripts produced in the region. This allowed for the characterization and localization of two new coding sequences, provisionally named HCG (for hemochromatosis candidate gene) and numbered VIII and IX.

Blotting, Northern↗
PubMed1996

A new non-HLA multigene family associated with the PERB11 family within the MHC class I region.

In an effort to initiate steps designed to characterize the idiopathic hemochromatosis disease gene, the HLA-A/HLA-F region where this gene is in disequilibrium linkage with some polymorphic markers has been overlapped by a yeast artificial chromosome (YAC) contig. In order to achieve the physical mapping of these YACs and of the corresponding genomic region, we subcloned one of the YACs involved. A computer-assisted analysis of the sequence of one subclone led to the isolation of a potential exon that proved to belong to a new expressed messenger named HCGIX. After Southern blot analysis, the corresponding cDNA clone was found to belong to a new multigene family whose members are dispersed throughout the HLA class I region and are closely associated with members of another recently described multigene family designated PERB11. The data reported here suggest that these two multigene families form a cluster that have been dispersed together throughout the telomeric part of the major histocompatibility complex and have been involved in the genesis of this human class I region.

Base Sequence↗
PubMed1996

Cloning of a human homologue of the mouse Tctex-5 gene within the MHC class I region.

Using a positional cloning strategy to identify the hemochromatosis gene (HFE), we isolated seven cDNAs by cDNA selection from a region of 400 kilobases (kb) located near the HLA-A and HLA-F loci. In this paper, we report the study of one of the corresponding genes, referred to as HCG V (hemochromatosis candidate gene), localized 150 kb centromeric to HLA-A. This gene was found to be expressed ubiquitously in the form of a 1.8 kb transcript, and to be apparently well conserved during evolution. The gene spanned 3.1 kb and is organized in three exons and two introns. The cDNA of 1620 base pairs (bp) showed an open reading frame of 378 bp, encoding for a 126 amino acid polypeptide which displayed a strong identity with the predicted product of a mouse Tctex-5 gene (t complex, testis expressed) localized in the t complex on chromosome 17. The HCG V gene was assessed as a potential candidate for hemochromatosis in regard to its localization in the linkage disequilibrium area between HFE and polymorphic markers. The study of deletions and point mutations in hemochromatosis patients revealed a single bp polymorphism within the coding region; however, no associated disease changes were found. Therefore we conclude that HCG V is unlikely to be involved in the pathogenesis of hemochromatosis.

Amino Acid Sequence↗
PubMed1996

[Bilateral pneumothorax and hemorrhagic rectocolitis].

BACKGROUND: Respiratory diseases associated with ulcerative colitis are rare. CASE REPORT: A 14-year-old girl with ulcerative colitis was admitted for a left pneumothorax. She was given corticoidsteroids and enemas of 5 aminosalicylic acid. The pneumothorax was not controlled by pleural drainage and a pleural irritation was performed under thoracoscopy. Recurrence of pneumothorax led to surgical pleurectomy. The following day, a right pneumothorax occurred, also requiring pleurectomy. The pulmonary biopsies showed constrictive bronchiolitis. A restrictive syndrome was confirmed by functional pulmonary examinations. Total colectomy was performed nine months later for the ulcerative colitis. COMMENTS: Ulcerative colitis can be associated with bronchial pathology (bronchitis, bronchiectasis). Occurrence of pneumothorax has never been described; it can be a fortuitous association, but the histological features are not very different from those described in association with ulcerative colitis. The treatment of pneumothorax is difficult if the ulcerative colitis requires corticosteroids.

Adolescent↗
PubMed1996

MR imaging of the prostate and seminal vesicles.

The important pathologic processes that affect the prostate are reviewed, with an emphasis on MR imaging of prostate cancer and benign prostatic hyperplasia. MR imaging of the seminal vesicles is also discussed.

Carcinoma↗
PubMed1995

Dose-discrimination performance of mice for self-administration of morphine into the lateral hypothalamus.

Two experiments were performed in BALB/c mice implanted bilaterally with guide cannulae. In the first experiment, the tips of the guide cannulae were positioned 1.5 mm above the lateral hypothalamus (LH). On each experimental day, injection cannulae were inserted into each side of the LH. The experiment, carried out in a Y-maze, was composed of two phases. During the initial acquisition period, which lasted 4 days, animals were allowed to self-inject, successively, on alternate days, one dose of morphine into one side of the LH and a different dose in the other side. From the fifth day, the subjects were given the possibility of choosing between these two doses by entering into a given arm of the Y-maze. When the two doses available were 5 ng and 50 ng or 15 ng and 50 ng, the subjects rapidly discriminated them and preferentially triggered the injection of the higher dose (50 ng). When the two doses available were 30 ng and 50 ng, the mice triggered indifferently the two doses during the first three sessions. A discrimination between these two doses began to become apparent from the fourth session, with the subjects preferring to trigger the dose of 50 ng. In a second experiment, the tips of the guide cannulae were positioned either 1.5 mm or 2.6 mm above the LH, the bilateral injection cannulae consequently being inserted either into the LH or into the overlying ventral thalamus (TH). Experimental conditions were the same as that of Experiment 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The amino-terminal part of ActA is critical for the actin-based motility of Listeria monocytogenes; the central proline-rich region acts as a stimulator.

The intracellular bacterial pathogen Listeria monocytogenes moves inside the host-cell cytoplasm propelled by continuous actin assembly at one pole of the bacterium. This process requires expression of the bacterial surface protein ActA. Recently, in order to identify the regions of ActA which are required for actin assembly, we and others have expressed different domains of ActA by transfection in eukaryotic cells. As this type of approach cannot address the role of ActA in the actin-driven bacterial propulsion, we have now generated several L. monocytogenes strains expressing different domains of ActA and analysed the ability of the different domains to trigger actin assembly and bacterial movement in both infected cells and cytoplasmic extracts. We show here that the amino-terminal part is critical for F-actin assembly and movement. The internal proline-rich repeats and the carboxy-terminal domains are not essential. However, in vitro motility assays have demonstrated that mutants lacking the proline-rich repeats domain of ActA moved two times slower (6+/-2 micrometers min(-1)) than the wild type (13 +/-3 micrometers min(-1)). In addition, phosphatase treatment of protein extracts of cells infected with the L. monocytogenes strains expressing the ActA variants suggested that phosphorylation may not be essential for ActA activity.

Actins↗
PubMed1994

A comparative study of self-administration of morphine into the amygdala and the ventral tegmental area in mice.

BALB/c mice were unilaterally implanted with a guide-cannula, the tip of which was positioned 1.5 mm above either the amygdala (AMY) or the ventral tegmental area (VTA). On each experimental day, a stainless-steel injection cannula was inserted into these structures in order to compare the self-administration of two doses of morphine (5 ng or 50 ng) in independent groups using a spatial discrimination task in a Y-maze. During the acquisition phase, both AMY and VTA injected mice showed a regular self-administration response at the two doses used. The latency to trigger the injection was short, particularly in the VTA group. Subcutaneous injection of naloxone (4 mg/kg) in trained mice reduced the number of self-administrations to a level near to chance in both groups, which suggests that the drug-seeking behavior observed is effectively dependent on an opiate receptor-mediated mechanism. However the rate of extinction was more rapid in AMY than in VTA injected mice. The 'perseveration' response exhibited by the VTA group during the withdrawal precipitated by naloxone may probably be due to the strong motivational and/or rewarding effect of morphine when injected in this brain structure during acquisition.

Amygdala↗
PubMed1994

Differentiation of intracranial morphine self-administration behavior among five brain regions in mice.

BALB/c mice were unilaterally implanted with a guide cannula, the tip of which was positioned 1.5 mm above either the lateral hypothalamus (LH) the medial hypothalamus (MH), the mesencephalic central gray area (CG), or either the dorsal (DRF) or ventral parts (VRF) of the reticular formation. On each day of the experimental period a stainless steel injection cannula was inserted into these brain structures to compare the self-administration of two doses of morphine (5 ng or 50 ng), using a spatial discrimination task in a Y-maze. At the dose of 5 ng, LH-, MH-, CG-, and VRF-injected mice all showed a regular self-administration response. At the dose of 50 ng, a discrimination between the reinforced arm and the neutral arm of the Y-maze was observed in LH-, MH-, and VRF-injected mice. Animals of the MH group exhibited the highest level of discrimination performance. At this dose, long injection latencies (> 15 min) were recorded in the CG group, which constrained us to reduce the number of daily trials from 10 to 4. In these modified conditions, CG animals clearly self-injected the dose of 50 ng of morphine. Subcutaneous injections of naloxone (4 mg/kg) reduced the number of self-administrations of morphine at each of the four responding structures. Marked signs of physical dependence (escape attempts) were observed in the four groups but with a higher frequency in CG and MH animals. When the injections of naloxone were suspended, a regular self-administration reappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗