Biomedical subjects

E Dubois

Publications and source records attributed to E Dubois.

At least 19 recordsLinked to original sources

PubMed2002

Identification of bluetongue virus serotype 2 (Corsican strain) by reverse-transcriptase PCR reaction analysis of segment 2 of the genome.

In October 2000, bluetongue virus was detected on the French island of Corsica. The disease was also reported in Sardinia, Calabria, Sicily and on the Spanish islands of Majorca and Minorca. This paper describes the use of molecular techniques for a rapid identification and serotype determination of serotype 2 of the virus. The nucleotide sequences of segments 2 and 7 of the genome of the Corsican strain were determined and its phylogenetic relationships are described.

Animals↗

PubMed2002

Anisotropy of the structure factor of magnetic fluids under a field probed by small-angle neutron scattering.

Small-angle neutron scattering is used to measure the two-dimensional diffraction pattern of a monophasic magnetic colloid, under an applied magnetic field. This dipolar system presents in zero field a fluidlike structure. It is well characterized by an interaction parameter K(0)(T) proportional to the second virial coefficient, which is here positive, expressing a repulsion of characteristic length kappa-10. Under the field a strong anisotropy is observed at the lowest q vectors. The length kappa-10 remains isotropic, but the interaction parameter K(T) becomes anisotropic due to the long-range dipolar interaction. However, the system remains stable, the interaction being repulsive in all directions. Thus we do not observe any chaining of the nanoparticles under magnetic field. On the contrary, the revealed structure of our anisotropic colloid is a lowering of the concentration fluctuations along the field while the fluidlike structure, observed without field, is roughly preserved perpendicularly to the field. It expresses a strong anisotropy of the Brownian motion of the nanoparticles in the solution under applied field.

Journal Article↗

PubMed2002

[Value and practice of in-home "low-vision" rehabilitation in Rhone-Alp region of France].

INTRODUCTION: To demonstrate the interest of patient's home orthoptist deplacement to realize an in-home low-vision rehabilitation and encourage orthoptists to integrate this task in their usual work methods. PATIENTS AND METHODS: Eighty-five consecutive patients coming from a private ophthalmic rehabilitation Center and needing low-vision rehabilitation, were studied. The exercises used at patient's home were usually the same as those used in the rehabilitation Center. The choice in the organization of rehabilitation was always function of patient general health, people vicinity, and social context. RESULTS: Among the 85 patients, 60 (70.6%) were rehabilitated only in the ophthalmic Center, 11 (12.9%) could have a low-vision rehabilitation only thanks to the organization of the home's patient rehabilitation and 14 (16.5%) were both rehabilitated at the ophthalmic Center and, in the patient's home, some training was necessary too. The reasons for in-home low-vision rehabilitation were mainly represented by isolation problems, mobilisation physical capacities, but also, home installation conditions making difficult to realize the orthoptist recommendations. DISCUSSION: Besides some disadvantages: time-consuming, badly paid, decrease of efficiency in familiar environment, advantages are easily objected: ergonomy, training on optic systems, and psychological comfort. CONCLUSION: In-home low-vision rehabilitation is represented by the necessity of correctly taking care of each patient. It is an answer to a social demand and must be an integral part of low-vision orthoptist work.

Adult↗

PubMed2001

A methodological tool for computer-assisted surgery interface design: its application to computer-assisted pericardial puncture.

Computer Assisted Surgery systems are becoming more and more prevalent. Design processes currently used, pay only a small attention to the surgeon's interaction. To address this lack in design, we propose the OP-a-S notation: OP-a-S modeling of a system adopts an interaction-centered point of view and highlights the links between the real world and the virtual world. Based on an OP-a-S modeling, predictive usability analysis can be performed by considering the ergonomic property. We illustrate our method on the retro-design of a computer assisted surgical application, CASPER.

Computer Simulation↗

PubMed2000

Inositol polyphosphate kinase activity of Arg82/ArgRIII is not required for the regulation of the arginine metabolism in yeast.

Arg82, a nuclear regulator of diverse cellular processes in yeast, is an inositol polyphosphate kinase. Some defects such as the regulation of arginine metabolism observed in an arg82Delta, result from a lack of Mcm1 and Arg80 stability. We show here that neither the kinase activity of Arg82 nor inositol phosphates are required for the control of arginine metabolism. Arg82 mutations keeping kinase active affect the expression of arginine genes, whereas mutations in the kinase domain do not impair this metabolic control.

Arginine↗

PubMed2000

Computer-guided pericardiocentesis: experimental results and clinical perspectives.

Percutaneous pericardial puncture is a relatively safe and effective technique in case of large pericardial effusions when practiced under echographic or radiological control. The goal of our project is to improve the performance of this technique, mainly in case of smaller and loculated effusions using an accurate guidance towards a preplanned target, based on a model of the pericardial effusion. This paper presents preclinical results of this new computer-assisted technique used to reach the pericardial cavity. The procedure is divided into 3 steps: 1. acquisition of ultrasound data, using an echocardiographic device connected to a 3-D localizer and to a computer, 2. modeling procedure to define the optimal strategy taking into account the mobility of organs on a digital model, 3. guided puncture with a localized needle to reach the predefined target using a passive guidance system. After validation on a dynamic phantom and a feasibility study on dogs, an accuracy and reliability analysis protocol was realized on pigs with experimental pericardial effusion. Feasibility of the technique is demonstrated on animal study with an accuracy of at least 2.5 mm. Further clinical investigation is in progress using a more ergonomic and less cumbersome system. This study demonstrates the feasibility of computer-assisted pericardiocentesis. Beyond the simple improvement of the current technique, this could be a new way to reach the heart or a new tool for percutaneous access and image-guided puncture of soft tissues.

Animals↗

PubMed2000

Characterisation of a tripartite nuclear localisation sequence in the regulatory protein Lys14 of Saccharomyces cerevisiae.

The Lys14 regulatory protein of Saccharomyces cerevisiae activates the expression of the LYS genes involved in the lysine biosynthetic pathway. Studies with a fused Lys14-green fluorescent protein reveal that Lys14p is localised to the nucleus, even under growth conditions leading to the absence of LYS gene expression. Lys14p nuclear localisation is mediated by a tripartite sequence made up of three short basic motifs located on the C-terminal side of the Zn cluster domain of Lys14p. Substitution of basic residues by alanines in any of the three motifs partially prevents the nuclear import of the protein. Simultaneous mutations in the three basic domains are required to completely abolish the entry into the nucleus and to impair the Lys14 function.

Active Transport, Cell Nucleus↗

PubMed2000

Recruitment of the yeast MADS-box proteins, ArgRI and Mcm1 by the pleiotropic factor ArgRIII is required for their stability.

Regulation of arginine metabolism requires the integrity of four regulatory proteins, ArgRI, ArgRII, ArgRIII and Mcm1. To characterize further the interactions between the different proteins, we used the two-hybrid system, which showed that ArgRI and Mcm1 interact together, and with ArgRII and ArgRIII, without an arginine requirement. To define the interacting domains of ArgRI and Mcm1 with ArgRIII, we fused portions of ArgRI and Mcm1 to the DNA-binding domain of Gal4 (GBD) and created mutations in GBD-ArgRI and GBD-Mcm1. The putative alpha helix present in the MADS-box domain of ArgRI and Mcm1 is their major region of interaction with ArgRIII. Interactions between the two MADS-box proteins and ArgRIII were confirmed using affinity chromatography. The requirement for ArgRIII in the control of arginine metabolism can be bypassed in vitro as well as in vivo by overproducing ArgRI or Mcm1, which indicates that ArgRIII is not present in the protein complex formed with the 'arginine boxes'. We show that the impairment of arginine regulation in an argRIII deletant strain is a result of a lack of stability of ArgRI and Mcm1. A mutation in ArgRI, impairing its interaction with ArgRIII, leads to an unstable ArgRI protein in a wild-type strain. ArgRIII integrity is crucial for Mcm1 function, as shown by the marked decreased expression of five genes controlled by Mcm1. However, ArgRIII is likely to recruit other proteins in the yeast cell, as overexpression of Mcm1 does not compensate some physiological defects observed in an argRIII deletant strain.

Amino Acid Sequence↗

PubMed2000

Three-year study to assess human enteric viruses in shellfish.

The main pathogenic enteric viruses able to persist in the environment, such as hepatitis A virus (HAV), Norwalk-like virus (NLV), enterovirus (EV), rotavirus (RV), and astrovirus (AV), were detected by reverse transcription-PCR and hybridization in shellfish during a 3-year study. Oyster samples (n = 108), occasionally containing bacteria, were less frequently contaminated, showing positivity for AV (17%), NLV (23%), EV (19%), and RV (27%), whereas mussel samples, collected in areas routinely impacted by human sewage, were more highly contaminated: AV (50%), HAV (13%), NLV (35%), EV (45%), and RV (52%). Sequences obtained from HAV and NLV amplicons showed a great variety of strains, especially for NLV (strains close to Mexico, Snow Mountain Agent, or Norwalk virus). Viral contamination was mainly observed during winter months, although there were some seasonal differences among the viruses. This first study of virus detection over a fairly long period of time suggests that routine analysis of shellfish by a molecular technique is feasible.

Animals↗

PubMed2000

In Saccharomyces cerevisiae, expression of arginine catabolic genes CAR1 and CAR2 in response to exogenous nitrogen availability is mediated by the Ume6 (CargRI)-Sin3 (CargRII)-Rpd3 (CargRIII) complex.

The products of three genes named CARGRI, CARGRII, and CARGRIII were shown to repress the expression of CAR1 and CAR2 genes, involved in arginine catabolism. CARGRI is identical to UME6 and encodes a regulator of early meiotic genes. In this work we identify CARGRII as SIN3 and CARGRIII as RPD3. The associated gene products are components of a high-molecular-weight complex with histone deacetylase activity and are recruited by Ume6 to promoters containing a URS1 sequence. Sap30, another component of this complex, is also required to repress CAR1 expression. This histone deacetylase complex prevents the synthesis of the two arginine catabolic enzymes, arginase (CAR1) and ornithine transaminase (CAR2), as long as exogenous nitrogen is available. Upon nitrogen depletion, repression at URS1 is released and Ume6 interacts with ArgRI and ArgRII, two proteins involved in arginine-dependent activation of CAR1 and CAR2, leading to high levels of the two catabolic enzymes despite a low cytosolic arginine pool. Our data also show that the deletion of the UME6 gene impairs cell growth more strongly than the deletion of the SIN3 or RPD3 gene, especially in the Sigma1278b background.

Arginase↗

PubMed2000

ArgRII, a component of the ArgR-Mcm1 complex involved in the control of arginine metabolism in Saccharomyces cerevisiae, is the sensor of arginine.

Repression of arginine anabolic genes and induction of arginine catabolic genes are mediated by a three-component protein complex, interacting with specific DNA sequences in the presence of arginine. Although ArgRI and Mcm1, two MADS-box proteins, and ArgRII, a zinc cluster protein, contain putative DNA binding domains, alone they are unable to bind the arginine boxes in vitro. Using purified glutathione S-transferase fusion proteins, we demonstrate that ArgRI and ArgRII1-180 or Mcm1 and ArgRII1-180 are able to reconstitute an arginine-dependent binding activity in mobility shift analysis. Binding efficiency is enhanced when the three recombinant proteins are present simultaneously. At physiological concentration, the full-length ArgRII is required to fulfill its functions; however, when ArgRII is overexpressed, the first 180 amino acids are sufficient to interact with ArgRI, Mcm1, and arginine, leading to the formation of an ArgR-Mcm1-DNA complex. Several lines of evidence indicate that ArgRII is the sensor of the effector arginine and that the binding site of arginine would be the region downstream from the zinc cluster, sharing some identity with the arginine binding domain of bacterial arginine repressors.

Amino Acid Sequence↗

PubMed1999

In Saccharomyces cerevisae, feedback inhibition of homocitrate synthase isoenzymes by lysine modulates the activation of LYS gene expression by Lys14p.

Expression of the structural genes for lysine biosynthesis responds to an induction mechanism mediated by the transcriptional activator Lys14p in the presence of alpha-aminoadipate semialdehyde (alphaAASA), an intermediate of the pathway acting as a coinducer. This activation is reduced by the presence of lysine in the growth medium, leading to apparent repression. In this report we demonstrate that Saccharomyces cerevisiae possesses two genes, LYS20 and LYS21, encoding two homocitrate synthase isoenzymes which are located in the nucleus. Each isoform is inhibited by lysine with a different sensitivity. Lysine-overproducing mutants were isolated as resistant to aminoethylcysteine, a toxic lysine analog. Mutations, LYS20fbr and LYS21fbr, are allelic to LYS20 and LYS21, and lead to desensitization of homocitrate synthase activity towards lysine and to a loss of apparent repression by this amino acid. There is a fair correlation between the I0.5 of homocitrate synthase for lysine, the intracellular lysine pool and the levels of Lys enzymes, confirming the importance of the activity control of the first step of the pathway for the expression of LYS genes. The data are consistent with the conclusion that inhibition by lysine of Lys14p activation results from the control of alphaAASA production through the feedback inhibition of homocitrate synthase activity.

2-Aminoadipic Acid↗

PubMed1998

A nonameric core sequence is required upstream of the LYS genes of Saccharomyces cerevisiae for Lys14p-mediated activation and apparent repression by lysine.

The expression of the structural genes for lysine (LYS) biosynthesis is controlled by a pathway-specific regulation mediated by the transcriptional activator Lys14 in the presence of alpha-aminoadipate semialdehyde, an intermediate of the pathway acting as a co-inducer. Owing to end product inhibition of the first step of the pathway, excess lysine reduces the production of the co-inducer and causes apparent repression of the LYS genes. Analysis of LYS promoters and insertions within an heterologous reporter gene have allowed the characterization of an upstream activating element (UASLYS) able to confer Lys14- and alpha-amino-adipate semialdehyde-dependent activation as well as apparent repression by lysine to another yeast gene. This DNA motif is present as one of several copies in the promoters of at least six LYS genes. The consensus sequence derived from the comparison of the UASLYS showing the highest activation capacities comprises the nonameric core sequence TCCRNYGGA. The RNY sequence of the 3 bp spacer as well as the presence of flanking AT-rich regions on both sides of the core sequence appear essential for optimal activation. Further evidence that this element is the target of Lys14p was provided by the demonstration that Lys14p binds to UASLYS in vitro. The binding is independent of the presence of the co-inducer and is not affected by lysine. It depends on the integrity of the putative Zn(II)2Cys6 binuclear cluster contained in the Lys14p.

Artificial Gene Fusion↗

PubMed1997

The nucleotide sequence of Saccharomyces cerevisiae chromosome XII.

The yeast Saccharomyces cerevisiae is the pre-eminent organism for the study of basic functions of eukaryotic cells. All of the genes of this simple eukaryotic cell have recently been revealed by an international collaborative effort to determine the complete DNA sequence of its nuclear genome. Here we describe some of the features of chromosome XII.

Base Sequence↗

PubMed1997

The nucleotide sequence of Saccharomyces cerevisiae chromosome XIV and its evolutionary implications.

In 1992 we started assembling an ordered library of cosmid clones from chromosome XIV of the yeast Saccharomyces cerevisiae. At that time, only 49 genes were known to be located on this chromosome and we estimated that 80% to 90% of its genes were yet to be discovered. In 1993, a team of 20 European laboratories began the systematic sequence analysis of chromosome XIV. The completed and intensively checked final sequence of 784,328 base pairs was released in April, 1996. Substantial parts had been published before or had previously been made available on request. The sequence contained 419 known or presumptive protein-coding genes, including two pseudogenes and three retrotransposons, 14 tRNA genes, and three small nuclear RNA genes. For 116 (30%) protein-coding sequences, one or more structural homologues were identified elsewhere in the yeast genome. Half of them belong to duplicated groups of 6-14 loosely linked genes, in most cases with conserved gene order and orientation (relaxed interchromosomal synteny). We have considered the possible evolutionary origins of this unexpected feature of yeast genome organization.

Base Sequence↗

PubMed1997

Integration of the multiple controls regulating the expression of the arginase gene CAR1 of Saccharomyces cerevisiae in response to differentnitrogen signals: role of Gln3p, ArgRp-Mcm1p, and Ume6p.

Expression of the catabolic gene encoding arginase in Saccharomyces cerevisiae, CAR1, is controlled by multiple nitrogen signals, such as the presence of the inducer, arginine, and the nature and amount of the nitrogen source. The present study has determined or confirmed the identity of the proteins involved in these different controls, as well as their targets in the CAR1 promoter. We show that Gln3p activates CAR1 expression through the GATAA sequences in the absence of an optimal nitrogen source, such as ammonia, glutamine or asparagine. Ume6p, which also controls the expression of early meiotic genes, represses CAR1 expression through a sequence called URS, as a function of nitrogen availability. Thus, the responses to the quality of the nitrogen source and to nitrogen starvation are achieved through different cis- and trans-regulatory elements. At least one of the multiple Rap1p and Abf1p binding sites is required for the basal transcription of the gene. The UAS(arg), containing the previously defined "arginine boxes" is the region that responds to the inducer through the action of the ArgRp-Mcm1p proteins, and its deletion alone significantly affects growth on arginine as sole nitrogen source. The functional UAS(arg) is about 60 nucleotides long, and contains two sequences homologous to the binding site for MADS-box proteins, to which ArgRIp and Mcm1p belong. No obvious palindromic sequence similar to the binding site of Gal4p, Ppr1p or Put3p is present in the UAS(arg), although ArgRIIp contains a Zn(II)2Cys6 motif. Interestingly, we have found that induction of CAR1 expression by arginine in the presence of an optimal nitrogen source is counteracted by Gln3p, independently of its action at the GATAA sequences.

Arginase↗

PubMed1997

Lys80p of Saccharomyces cerevisiae, previously proposed as a specific repressor of LYS genes, is a pleiotropic regulatory factor identical to Mks1p.

In Saccharomyces cerevisiae, an intermediate of the lysine pathway, alpha-aminoadipate semialdehyde (alpha AASA), acts as a coinducer for the transcriptional activation of LYS genes by Lys14p. The limitation of the production of this intermediate through feedback inhibition of the first step of the pathway results in apparent repression by lysine. Previously, the lys80 mutations, reducing the lysine repression and increasing the production of lysine, were interpreted as impairing a repressor of LYS genes expression. In order to understand the role of Lys80p in the control of the lysine pathway, we have analysed the effects of mutations epistatic to lys80 mutations. The effects of lys80 mutations on LYS genes expression were dependent on the integrity of the activation system (Lys14p and alpha AASA). The increased production of lysine in lys80 mutants appeared to result from an improvement of the metabolic flux through the pathway and was correlated to an increase of the alpha-ketoglutarate pool and of the level of several enzymes of the tricarboxylic acid cycle. The LYS80 genes has been cloned and sequenced; it turned out to be identical to gene MKS1 cloned as a gene encoding a negative regulator of the RAS-cAMP pathway. We conclude that Lys80p is a pleiotropic regulatory factor rather than a specific repressor of LYS genes.

2-Aminoadipic Acid↗

PubMed1997

Molecular epidemiological survey of rotaviruses in sewage by reverse transcriptase seminested PCR and restriction fragment length polymorphism assay.

Rotavirus double-stranded RNA was detected directly in sewage treatment plant samples over a 1-year period by reverse transcription followed by PCR amplification of the VP7 gene and Southern blot hybridization. The presence of naturally occurring rotaviruses was demonstrated in 42% of raw sewage samples and in 67% of treated effluent samples. Amplified viral sequences were analyzed by restriction enzymes. Ten different restriction profiles were characterized, most of which were found in treated effluent samples. A mixture of restriction profiles was observed in 75% of contaminated effluent samples. The profiles were compared with those obtained from human rotavirus isolates involved in infections in children from the same area (six different profiles were detected). Five identical viral sequences were detected in both environmental and clinical samples. Restriction profiles were also compared to profiles from known genomic sequences of human and animal viruses. Both human and animal origins of rotavirus contamination of water seemed likely.

Animals↗