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Biomedical subjects

C Bonnard

Publications and source records attributed to C Bonnard.

At least 19 recordsLinked to original sources
PubMed2000

Myc induces the nucleolin and BN51 genes: possible implications in ribosome biogenesis.

The c-Myc oncoprotein and its dimerization partner Max bind the DNA core consensus sequence CACGTG (E-box) and activate gene transcription. However, the low levels of induction have hindered the identification of novel Myc target genes by differential screening techniques. Here, we describe a computer-based pre-selection of candidate Myc/Max target genes, based on two restrictive criteria: an extended E-box consensus sequence for Myc/Max binding and the occurrence of this sequence within a potential genomic CpG island. Candidate genes selected by these criteria were evaluated experimentally for their response to Myc. Two Myc target genes are characterized here in detail. These encode nucleolin, an abundant nucleolar protein, and BN51, a co-factor of RNA polymerase III. Myc activates transcription of both genes via E-boxes located in their first introns, as seen for several well-characterized Myc targets. For both genes, mutation of the E-boxes abolishes transcriptional activation by Myc as well as repression by Mad1. In addition, the BN51 promoter is selectively activated by Myc and not by USF, another E-box-binding factor. Both nucleolin and BN51 are implicated in the maturation of ribosomal RNAs, albeit in different ways. We propose that Myc, via regulation of these and probably many other transcriptional targets, may be an important regulator of ribosome biogenesis.

Cell Cycle Proteins↗
PubMed2000

The eukaryotic promoter database (EPD).

The Eukaryotic Promoter Database (EPD) is an annotated non-redundant collection of eukaryotic POL II promoters for which the transcription start site has been determined experimentally. Access to promoter sequences is provided by pointers to positions in nucleotide sequence entries. The annotation part of an entry includes a description of the initiation site mapping data, exhaustive cross-references to the EMBL nucleotide sequence database, SWISS-PROT, TRANSFAC and other databases, as well as bibliographic references. EPD is structured in a way that facilitates dynamic extraction of biologically meaningful promoter subsets for comparative sequence analysis. WWW-based interfaces have been developed that enable the user to view EPD entries in different formats, to select and extract promoter sequences according to a variety of criteria, and to navigate to related databases exploiting different cross-references. The EPD web site also features yearly updated base frequency matrices for major eukaryotic promoter elements. EPD can be accessed at http://www.epd.isb-sib.ch

Database Management Systems↗
PubMed2000

[Scapular pain and supra-scapular neuropathy in sports medicine].

Eight patients with shoulder pain are reported with a history of athletic activities. On examination, performed with a delay of several months, all patients had painful paresis and atrophy of spinati fossa. Electroneuromyography was carried out in all cases and showed a suprascapular nerve axonal loss from the spinati muscles or infraspinatus muscle, signs of denervation-reinnervation in spinati or infraspinatus muscles, normal examination of other scapular girdle muscles, and a coordinate spinati contraction with shoulder displacement excluding rotator cuff tears. All patients had conservative treatment and only two improved. Six patients underwent surgical decompression of the suprascapular nerve; in three, motor function clearly improved, and in three others pain improved. The factors leading to entrapment include stretch mechanisms associated with shoulder movements, leading to suprascapular nerve liability to mechanical lesions. In patients with shoulder pain, the authors recommend an early electrophysiological work-up to recognize an isolated suprascapular neuropathy. The surgical decompression of the nerve should be based on persistent shoulder pain after conservative treatment.

Adolescent↗
PubMed1999

The Eukaryotic Promoter Database (EPD): recent developments.

The Eukaryotic Promoter Database (EPD) is an annotated non-redundant collection of eukaryotic POL II promoters, for which the transcription start site has been determined experimentally. Access to promoter sequences is provided by pointers to positions in nucleotide sequence entries. The annotation part of an entry includes description of the initiation site mapping data, cross-references to other databases, and bibliographic references. EPD is structured in a way that facilitates dynamic extraction of biologically meaningful promoter subsets for comparative sequence analysis. Recent efforts have focused on exhaustive cross-referencing to the EMBL nucleotide sequence database, and on the improvement of the WWW-based user interfaces and data retrieval mechanisms. EPD can be accessed at http://www.epd.isb-sib.ch

Algorithms↗
PubMed1999

Isolated and combined lesions of the axillary nerve. A review of 146 cases.

We have assessed the final strength of the deltoid in 121 patients who had repair of isolated or combined lesions of the axillary (circumflex) nerve and were available for statistical analysis. Successful or useful results were achieved in 85% after grafting of isolated lesions. The strength was statistically better when patients had grafting of the axillary nerve within 5.3 months from the time of injury. The dramatic decrease in the rate of success seen with longer delays suggests that surgery should be undertaken within three months of injury. A statistically significant downward trend of the rate of success was noted with increasing age. The force and level of injury to the shoulder play an important role in the type, combination and level of nerve damage and the incidence of associated rotator-cuff, vascular and other injuries to the upper limb. Management of isolated and combined lesions of the axillary nerve after injury to the shoulder needs to be thorough and systematic.

Adolescent↗
PubMed1995

Restoration of hand function after brachial plexus injury.

Brachial plexus injuries effect hand function in different ways. Deficits may resemble those of a radial nerve palsy or those of an associated, high medioulnar paralysis. Analysis shows that active extension of the wrist is paramount in all procedures to gain quality results.

Brachial Plexus↗
PubMed1994

Optimal sequence and structure of iron-responsive elements. Selection of RNA stem-loops with high affinity for iron regulatory factor.

Iron regulatory factor (IRF) is a cytoplasmic mRNA-binding protein with specificity for iron-responsive element (IRE) RNA stem-loops. IRF post-transcriptionally regulates intracellular iron levels via binding to IREs in the untranslated regions of ferritin, transferrin receptor, and erythroid 5-aminolevulinic-acid synthase mRNAs. Specific IRE nucleotides are phylogenetically conserved: those of the 6-base loop (5'-CAGUGN-3') and an unpaired "bulge" cytosine. We prepared a pool of 16,384 IRE molecules randomized at these seven nucleotide positions and employed in vitro selection to identify RNAs that bind human IRF. Two major classes of high affinity RNA ligands were selected; the optimal loop sequences of each are 5'-CAGUGN-3' (wild type) and 5'-UAGUAN-3'. This novel finding predicts base pairing within the IRE loop between positions 1 and 5, thus facilitating the formation of a specific loop structure in which nucleotides at positions 2-4 are made accessible for protein interaction. Nucleotide substitution at these loop positions, or at the position of the bulge cytosine, decreased binding by 36-99%. In addition, we demonstrate a preferred IRE bulge structure and report a striking difference in the RNA binding specificity of rat IRF compared with that of the related IRE-binding protein, IRFB.

Animals↗
PubMed1994

[Epiphyseal separations of the knee].

Basic principles of treatment of distal femoral and proximal tibial growth plate injuries are described in relation to the anatomical lesions using the Salter-Harris classification. Some strategic recommendations are made for complex fractures: the articular surface must first be reconstructed followed by the metaphysis if possible.

Adolescent↗