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B Cornet

Publications and source records attributed to B Cornet.

At least 19 recordsLinked to original sources
PubMed2005

Decision analysis for the assessment of a record linkage procedure: application to a perinatal network.

OBJECTIVES: According to European legislation, we must develop computer software allowing the linkage of medical records previously rendered anonymous. Some of them, like AUTOMATCH, are used in daily practice either to gather medical files in epidemiologic studies or for clinical purpose. In the first situation, the aim is to avoid homonymous errors, and in the second one, synonymous errors. The objective of this work is to study the effect of different parameters (number of identification variables, phonetic treatments of names, direct or probabilistic linkage procedure) on the reliability of the linkage in order to determine which strategy is the best according to the purpose of the linkage. METHODS: The assessment of the Burgundy Perinatal Network requires the linking of discharge abstracts of mothers and neonates, collected in all the hospitals of the region. Those data are used to compare direct and probabilistic linkage, using different parameterization strategies. RESULTS: If the linkage has to be performed in real time, so that no validation of indecisions generated by probabilistic linkage is possible, probabilistic linkage using three variables without any phonetic treatment seems to be the most appropriate approach, combined with a direct linkage using four variables applied to non-conclusive links. If a validation of indecisions is possible in an epidemiological study, probabilistic linkage using five variables, with a phonetic treatment adapted to the local language has to be preferred. For medical purpose, it should be combined with a direct linkage with four or five variables. CONCLUSION: This paper reveals that the time and money available to manage indecision as well as the purpose of the linkage are of paramount importance for choosing a linkage strategy.

France↗
PubMed2002

[Prospective regional study of an epidemic of respiratory syncytial virus (RSV) bronchiolitis].

UNLABELLED: This prospective study was designed to identify risk factors associated with admission in pediatric intensive care units (PICU) among infants hospitalized for treatment of RSV induced bronchiolitis. This study was population-based and was conducted in Burgundy, a French region with 1,800,000 inhabitants where passive immunoprophylaxis for RSV bronchiolitis was not set up at the time of the study. RESULTS: From December 1st 1999 to April 30th 2000, 484 infants were hospitalized for RSV bronchiolitis in Burgundy: 19.6% were born prematurely (gestational age [GA] below 37 weeks) and at admission, 68.3% had a postnatal age below six months (mean = 5 +/- 5.9 months; median value = 3 months). The duration of hospitalization was 7.3 +/- 12.4 days (median value = 6 days). Among the 484 infants, 31 (6.4%) needed admission in PICU, eight needed mechanical ventilation (1.7%) and one died (0.2%). Univariate analysis identified anamnestic risk factors associated with admission in PICU: prematurity; low birth weight; past history of neonatal respiratory distress syndrome (RDS); mechanical ventilation for RDS treatment; bronchopulmonary dysplasia (BPD) and congenital heart disease. Multivariate analysis identified three independent factors associated with an increased risk for admission in PICU: GA below 32 weeks; RDS and congenital heart disease. CONCLUSION: This study suggests that population at risk for severe RSV bronchiolitis with PICU admission should include all very preterm infants with RDS whatever the outcome of RDS (with or without BPD). These epidemiological data could be helpful to set up indications for passive immunoprophylaxis of RSV induced bronchiolitis.

Antibodies, Monoclonal↗
PubMed2001

[Using discharge abstracts as a tool to assess a regional perinatal network].

To assess the regional perinatal network of Burgundy (20 obstetrical units; 18,000 births/year), discharge abstracts are collected for all mothers and all neonates. Discharge abstracts are expanded with some additional data. According to the French law, data are rendered anonymous in each hospital before their transmission to the teaching hospital for statistical analysis. The linkage of all anonymous information concerning a patient is obtained. Moreover, this specific procedure allows the linkage of data concerning each mother and her corresponding neonate. This study shows that after an expanded data quality control, the linkage between data of the mothers and their infants is obtained in 99.8% of births.

Adult↗
PubMed2000

[Medical informatics (hospital information systems) in neonatology: reality and insufficiencies].

The generalized implementation in France of hospital information systems (HIS) is often considered by the medical practitioners as a useless constraint. Nevertheless, they are now largely used by the administrative authorities for their economical evaluation of medical care. In neonatology HIS is applied to the hospitalized sick neonates as well as to the healthy newborn infants during their maternity hospital stay with their mother following birth. This paper focuses on the practical aspects and difficulties of the current French HIS in neonatology.

Diagnosis-Related Groups↗
PubMed1999

[Current networks in perinatal care. From practice to theory...].

Perinatal care networks have been organized in a conventional way in six different French areas. This paper describes the four successive steps of this organization: description of the perinatal dysfunctions through survey(s), elaboration of medical recommendations, set up of a new organization, evaluation of the efficiency of the new organization.

Community Networks↗
PubMed1997

Refined solution structure of the anti-mammal and anti-insect LqqIII scorpion toxin: comparison with other scorpion toxins.

The solution structure of the anti-mammal and anti-insect LqqIII toxin from the scorpion Leiurus quinquestriatus quinquestriatus was refined and compared with other long-chain scorpion toxins. This structure, determined by 1H-NMR and molecular modeling, involves an alpha-helix (18-29) linked to a three-stranded beta-sheet (2-6, 33-39, and 43-51) by two disulfide bridges. The average RMSD between the 15 best structures and the mean structure is 0.71 A for C alpha atoms. Comparison between LqqIII, the potent anti-mammal AaHII, and the weakly active variant-3 toxins revealed that the LqqIII three-dimensional structure is closer to that of AaHII than to the variant-3 structure. Moreover, striking analogies were observed between the electrostatic and hydrophobic potentials of LqqIII and AaHII. Several residues are well conserved in long-chain scorpion toxin sequences and seem to be important in protein structure stability and function. Some of them are involved in the CS alpha beta (Cysteine Stabilized alpha-helix beta-sheet) motif. A comparison between the sequences of the RII rat brain and the Drosophila extracellular loops forming scorpion toxin binding-sites of Na+ channels displays differences in the subsites interacting with anti-mammal or anti-insect toxins. This suggests that hydrophobic as well as electrostatic interactions are essential for the binding and specificity of long-chain scorpion toxins.

Amino Acid Sequence↗
PubMed1996

1H-NMR-derived secondary structure and the overall fold of the potent anti-mammal and anti-insect toxin III from the scorpion Leiurus quinquestriatus quinquestriatus.

We describe the secondary structure and the overall fold of toxin III from the venom of the scorpion Leiurus quinquestriatus quinquestriatus determined using two-dimensional-1H-NMR spectroscopy. This protein, which contains 64 amino acids and 4 disulfide bridges, belongs to the long-chain toxin category and is highly toxic to both mammals and insects. The overall fold was determined on the basis of 1208 inter-proton-distance restraints derived from NOE measurements and 90 psi, phi dihedral-angle restraints derived from NOE connectivities and 3JNH-alphaH coupling constants using the HABAS program. This fold, which mainly consists of an alpha-helix packed against a small antiparallel three-stranded beta-sheet, and of several turns and loops, is similar to that of other long-chain scorpion toxins. Aromatic and non-polar residues form several patches on the surface of the protein which alternate with patches of charged and polar residues. Such a topology should be important in the interactions of toxin III with sodium channels in membranes. Two weakly constrained loops introduce some flexibility to the structure which could be related to the activity of this toxin. The central core of toxin III is compared with the cysteine-stabilized alpha beta motif (an alpha-helix connected to a beta-sheet through two disulfide bridges) found in insect defensins and plant thionins. Defensins and thionins are small proteins (approximately 40--50 amino acid residues) containing three or four disulfide bridges, respectively. This comparison confirms that the cysteine-stabilized alpha beta motif is a common core to a number of small proteins from different origins and having different activities.

Amino Acid Sequence↗
PubMed1995

Refined three-dimensional solution structure of insect defensin A.

BACKGROUND: Insect defensin A is a basic 4 kDa protein secreted by Phormia terranovae larvae in response to bacterial challenges or injuries. Previous biological tests suggest that the bacterial cytoplasmic membrane is the target of defensin A. The structural study of this protein is the first step towards establishing a structure-activity relationship and forms the basis for understanding its antibiotic activity at the molecular level. RESULTS: We describe a refined model of the three-dimensional structure of defensin A derived from an extensive analysis of 786 inter-proton nuclear Overhauser effects. The backbone fold involves an N-terminal loop and an alpha-helical fragment followed by an antiparallel beta-structure. The helix and the beta-structure are connected by two of the three disulphide bridges present in defensin A, forming a so-called 'cysteine-stabilized alpha beta' (CS alpha beta) motif. The N-terminal loop, which is locally well defined, can occupy different positions with respect to the other moieties of the molecule. CONCLUSIONS: The CS alpha beta motif, which forms the core of the defensin A structure, appears to be a common organization for several families of small proteins with toxic properties. The distribution of amino acid side chains in the protein structure creates several hydrophobic or hydrophilic patches. This leads us to propose that the initial step in the action of positively charged defensin A molecules with cytoplasmic membranes may involve interactions with acidic phospholipids.

Amino Acid Sequence↗
PubMed1993

Secondary structure of gp160 and gp120 envelope glycoproteins of human immunodeficiency virus type 1: a Fourier transform infrared spectroscopic study.

The secondary structure of the precursor (gp160) of the envelope protein of human immunodeficiency virus type 1 (BH10) and its receptor-binding subunit (gp120) was studied by Fourier-transformed attenuated total reflection spectroscopy. A higher alpha-helix/beta-sheet ratio in the gp120 subunit than in the precursor indicates a structural heterogeneity between the two subunits (gp120 and gp41), in agreement with classical secondary-structure predictions. The secondary structure of gp41 was estimated and compared with existing models. The high alpha-helical content in gp41 and the dominant beta-sheet content in gp120 resemble the distribution in influenza virus hemagglutinin subunits.

CD4 Antigens↗
PubMed1992

Properties of HIV membrane reconstituted from its recombinant gp160 envelope glycoprotein.

Human immunodeficiency virus (HIV) membrane has been reconstituted from the recombinant envelope glycoprotein precursor (gp160) by a detergent dialysis technique. Electron microscopy shows that gp160-virosomes are spherical vesicles with a mean diameter identical to that of viral particles. Enzyme-linked immunosorbent assay and immunogold labeling demonstrate efficient association of gp160 with lipid vesicles and proteolysis treatment reveals an asymmetric insertion with about 90% of glycoproteins having their gp120-moiety pointing outside. Glycoproteins are organized as dimers and tetramers and gp160 retains its ability to specifically bind CD4 receptor after reconstitution into virosome.

CD4 Antigens↗
PubMed1990

Orientation into the lipid bilayer of an asymmetric amphipathic helical peptide located at the N-terminus of viral fusion proteins.

The complete amino-acid sequence of viral fusion proteins has been analyzed by the Eisenberg procedure. The region surrounding the cleavage site contains a highly hydrophilic region immediately followed by a membrane-like region. Since the effective cleavage between these two domains seems required to expose the fusogenic domain (located at the N-terminal sequence of the transmembrane like region) which is assumed to interact with the lipid membrane of the host cell, we have focused our analysis on the conformation and mode of insertion of this membrane-like domain in a lipid monolayer. It was inserted as an alpha-helical structure into a dipalmitoylphosphatidylcholine (DPPC) monolayer and its orientation at the lipid/water interface was determined using a theoretical analysis procedure allowing the assembly of membrane components. For each viral protein sequence these N-terminal helical segments oriented obliquely with respect to the lipid/water interface. This rather unusual orientation is envisaged as a prerequisite to membrane destabilization and fusogenic activity.

Amino Acid Sequence↗
PubMed1990

Characterization of monoclonal antibodies against the p17 core protein of the human immunodeficiency virus 1.

Five mouse hybridomas which produce monoclonal antibodies against the p17 core protein of HIV-1 have been isolated. Cross-competition assays and mapping with synthetic peptides demonstrate that two closely related epitopes are identified by these antibodies. Directed against two neighbouring peptides at the carboxy-terminal end of the molecule, they can be used for the selective detection of p17 polypeptide in a viral extract or in an infected cell lysate by a solid-phase sandwich enzyme immunoassay.

Amino Acid Sequence↗
PubMed1990

Virosomes reconstituted from human immunodeficiency virus proteins and lipids.

Purified Human Immunodeficiency Virus (HIV) was solubilized in octylglucopyranoside. After centrifugation, the supernatant was added to lipid-detergent mixed micelles. Formation of virosomes occurred during overnight dialysis. Centrifugation on a continuous glycerol gradient showed that envelope glycoproteins (gp120 and gp41) and matrix protein p17 but not core protein p25 were associated to virosomes. Proteolytic treatment of virosomes indicates that gp120 is oriented toward the outside as in the virus particles, whereas p17 protein is anchored on both sides of the liposomal membrane. Virosomes are spherical vesicles with approximately the size of the virus as shown by electron microscopy.

Blotting, Western↗
PubMed1988

Mode of insertion into a lipid membrane of the N-terminal HIV gp41 peptide segment.

The complete amino-acid sequence of the gp160 polyprotein of HIV (strain WMJ1) has been analyzed by the Eisenberg procedure. The region surrounding the cleavage site between the gp120 and the gp41 subunit contains a receptor-like region immediately followed by a transmembrane-like region containing approximately 13 residues. These two regions are separated by the cleavage site between gp120 and gp41. Since the same arrangement exists in some paramyxoviruses (unpublished observation) and since the effective cleavage between a receptor-like region and the transmembrane-like region is required in paramyxoviruses to generate fusogenic segment (located at the N-terminal sequence of the transmembrane-like region), we have focused our analysis on the conformational properties of the N-terminal peptide segment of HIV gp41. This peptide segment, which consists of a helical structure according to Garnier prediction, was oriented at the lipid-water interface using a theoretical analysis method that we recently developed. Analysis of the transmembrane peptide determined by Eisenberg method shows that the helical segment orients itself in the lipid monolayer obliquely with respect to the lipid-water interface. Since this rather unusual orientation for a membrane segment of a protein is also found in the fusogenic peptide of the Newcastle Disease Virus (Virus Genes, in press) and seems to possess membrane destabilizing properties, it is in agreement with previous reports suggesting a fusogenic role for the N-terminal part of gp41.

HIV↗
PubMedDate not supplied

Progress in multidimensional NMR investigations of peptide and protein 3-D structures in solution. From structure to functional aspects.

2-D and 3-D NMR techniques were used to investigate the conformations in solution of several peptides and proteins for which crystalline structures are not available yet. Insect defensin A is a small (40 aa) antibiotic protein exhibiting a characteristic 'loop-helix-beta-sheet' structure. A striking analogy was found with charybdotoxin, a scorpion toxin in which a CSH (cysteine stabilized alpha-helix) motif is also present. Wheat phospholipid transfer protein (PLTP) (90 aa) has a 3-D structure resulting from the packing of four helices and of a C-terminal less well-defined fragment. Preliminary results show that PLTP forms a complex with lyso-PC and that such an interaction results in a conformational change affecting principally the C-terminal half of the protein. A last example is given with surfactin, a lipopeptide biosurfactant from bacterial origin. Its protonated form shows a very compact structure in which the two acidic residues located on the top of a 'horse saddle' topology face each other, whereas the ionized form could adopt a more extended conformation. A common property of these compounds is their capacity to interact with lipids. The present structural data open the way for a further establishment of structure-activity relationships.

Amino Acid Sequence↗