Terrorist attacks in Paris: Surgical trauma experience in a referral center.

Background: On November 13th, 2015, terrorist bomb explosions and gunshots occurred in Paris, France, with 129 people immediately killed, and more than 300 being injured. This article describes the staff organization, surgical management, and patterns of injuries in casualties who were referred to the Teaching European Hospital Georges Pompidou.

Methods: This study is a retrospective analysis of the pre-hospital response and the in-hospital response in our referral trauma center.

Comparisons between geographically diverse samples of carried Staphylococcus aureus.

Approximately one-third of the human population is asymptomatically colonized by Staphylococcus aureus. However, much of the global diversity within the carriage populations remains uncharacterized, and it is unclear to what degree the variation is geographically partitioned. We isolated 300 carriage isolates from 1,531 adults contemporaneously in four countries: France, Algeria, Moldova, and Cambodia.

Diversity of staphylococcal cassette chromosome mec structures in methicillin-resistant Staphylococcus epidermidis and Staphylococcus haemolyticus strains among outpatients from four countries.

In staphylococci, methicillin (meticillin) resistance (MR) is mediated by the acquisition of the mecA gene, which is carried on the size and composition variable staphylococcal cassette chromosome mec (SCCmec). MR has been extensively studied in Staphylococcus aureus, but little is known about MR coagulase-negative staphylococci (MR-CoNS). Here, we describe the diversity of SCCmec structures in MR-CoNS from outpatients living in countries with contrasting environments: Algeria, Mali, Moldova, and Cambodia.

A reliable diagnosis of human rabies based on analysis of skin biopsy specimens.

Background: The number of human deaths due to rabies is currently underestimated to be 55,000 deaths per year. Biological diagnostic methods for confirmation of rabies remain limited, because testing on postmortem cerebral samples is the reference method, and in many countries, sampling brain tissue is rarely practiced. There is a need for a reliable method based on a simple collection of nonneural specimens.

Influenza A/H5N1 virus infection in humans in Cambodia.

Background: Between January 2005 and April 2006, six patients of influenza A/H5N1 virus infection were reported in Cambodia, all with fatal outcome.

Objectives: We describe the virological findings of these six H5N1 patients in association with clinical and epidemiologic findings.

Study Design: Broncho-alveolar lavage, nasopharyngeal, throat and rectal swabs and sera were cultured for virus isolation and viral load quantified in clinical specimens by real-time RT-PCR.

Low frequency of poultry-to-human H5NI virus transmission, southern Cambodia, 2005.

To understand transmission of avian influenza A (H5N1) virus, we conducted a retrospective survey of poultry deaths and a seroepidemiologic investigation in a Cambodian village where a 28-year-old man was infected with H5N1 virus in March 2005. Poultry surveys were conducted within a 1-km radius of the patient's household. Forty-two household flocks were considered likely to have been infected from January through March 2005 because >60% of the flock died, case-fatality ratio was 100%, and both young and mature birds died within 1 to 2 days.

Study of structure and orientation of mesentericin Y105, a bacteriocin from Gram-positive Leuconostoc mesenteroides, and its Trp-substituted analogues in phospholipid environments.

Mesentericin Y105 (Mes-Y105) is a bacteriocin secreted by Leuconostoc mesenteroides which is particularly active on Listeria. It is constituted by 37 residues and reticulated by one disulfide bridge. It has two W residues, W18 and W37, which can be studied by fluorescence.

The C-terminal t peptide of acetylcholinesterase forms an alpha helix that supports homomeric and heteromeric interactions.

Acetylcholinesterase subunits of type T (AChET) possess an alternatively spliced C-terminal peptide (t peptide) which endows them with amphiphilic properties, the capacity to form various homo-oligomers and to associate, as a tetramer, with anchoring proteins containing a proline rich attachment domain (PRAD). The t peptide contains seven conserved aromatic residues. By spectroscopic analyses of the synthetic peptides covering part or all of the t peptide of Torpedo AChET, we show that the region containing the aromatic residues adopts an alpha helical structure, which is favored in the presence of lipids and detergent micelles: these residues therefore form a hydrophobic cluster in a sector of the helix.

The antibiotic activity of cationic linear amphipathic peptides: lessons from the action of leucine/lysine copolymers on bacteria of the class Mollicutes.

Peptides composed of leucyl and lysyl residues ('LK peptides') with different compositions and sequences were compared for their antibacterial activities using cell wall-less bacteria of the class Mollicutes (acholeplasmas, mycoplasmas and spiroplasmas) as targets. The antibacterial activity of the amphipathic alpha-helical peptides varied with their size, 15 residues being the optimal length, independent of the membrane hydrophobic core thickness and the amount of cholesterol. The 15-residue ideally amphipathic alpha helix with a +5 positive net charge (KLLKLLLKLLLKLLK) had the strongest antibacterial activity, similar to that of melittin.

Secondary structure of spiralin in solution, at the air/water interface, and in interaction with lipid monolayers.

The surface of spiroplasmas, helically shaped pathogenic bacteria related to the mycoplasmas, is crowded with the membrane-anchored lipoprotein spiralin whose structure and function are unknown. In this work, the secondary structure of spiralin under the form of detergent-free micelles (average Stokes radius, 87.5 A) in water and at the air/water interface, alone or in interaction with lipid monolayers was analyzed.

Dynamics and orientation of amphipathic peptides in solution and bound to membranes: a steady-state and time-resolved fluorescence study of staphylococcal delta-toxin and its synthetic analogues.

The environment of both the hydrophilic and hydrophobic sides of alpha-helical delta-toxin are probed by tryptophanyl (Trp) fluorescence, when self-association occurs in solution and on binding to membranes. The fluorescence parameters of staphylococcal delta-toxin (Trp15 on the polar side of the amphipathic helix) and synthetic analogues with single Trp at position 5 or 16 (on the apolar side) were studied. The time-resolved fluorescence decays of the peptides in solution show that the local environment of their single Trp is always heterogeneous.

The lipid charge density at the bilayer surface modulates the effects of melittin on membranes.

The influence of melittin on two DMPA membrane systems at pH 4.2 and 8.2 has been investigated by solid-state 31P and 2H NMR, as a function of temperature and peptide concentration.

Ideally amphipathic beta-sheeted peptides at interfaces: structure, orientation, affinities for lipids and hemolytic activity of (KL)(m)K peptides.

Designed to model ideally amphipathic beta-sheets, the minimalist linear (KL)(m)K peptides (m=4-7) were synthesized and proved to form stable films at the air/water interface, they insert into compressed dimyristoylphosphatidylcholine monolayers and interact with egg phosphatidylcholine vesicles. Whatever the interface or the lateral pressure applied to the films, FT-IR and polarization-modulated IRRAS spectroscopy developed in situ on the films indicated that all the peptides totally fold into intermolecular antiparallel beta-sheets. Calculated spectra of the amide region allowed us to define the orientation of the beta-strands compared to the interface.

Structure, orientation and affinity for interfaces and lipids of ideally amphipathic lytic LiKj(i=2j) peptides.

The behavior of lytic ideally amphipathic peptides of generic composition LiKj(i=2j) and named LKn, n=i+j, is investigated in situ by the monolayer technique combined with the recently developed polarization modulation IR spectroscopy (PMIRRAS). A change in the secondary structure occurs versus peptide length. Peptides longer than 12 residues fold into alpha-helices at interfaces as expected from their design, while enough shorter peptides, from 9 down to 5 residues, form intermolecular antiparallel beta-sheets.

The amphipathic helix concept: length effects on ideally amphipathic LiKj(i=2j) peptides to acquire optimal hemolytic activity.

In a minimalist approach to modeling lytic toxins, amphipathic peptides of LiKj with i=2j composition and whose length varies from 5 to 22 residues were studied for their ability to induce hemolysis and lipid vesicle leakage. Their sequences were designed to generate ideally amphipathic alpha helices with a single K residue per putative turn. All the peptides were lytic, their activities varying by more than a factor of 103 from the shortest 5-residue-long peptide (5-mer) to the longest 22-mer.

Investigation of an outbreak of wound infections due to Alcaligenes xylosoxidans transmitted by chlorhexidine in a burns unit.

Alcaligenes xylosoxidans, an environmental gram-negative bacillus, was isolated within a 1-month period from six patients in a pediatric burns unit. Twelve isolates were studied, one from each of the six patients (five from wound cultures and one from a blood culture) and one from each of six contaminated atomizers containing chlorhexidine diluted to 600 mg/l. The biochemical and susceptibility patterns of all the isolates were similar, and their DNA enzyme restriction patterns were identical.

Molecular assembling of DNA with amphipathic peptides.

The self-assembling of double-stranded DNA with short synthetic peptides has been analysed using the fluorescent properties of the intercalating dye, ethidium bromide. Two membrane-active peptides with appropriate sequences of lysine and leucine amino acids and a short polylysine have been probed. The results revealed that the secondary structure of the peptide decisively aimed the peptide-DNA complex formation: only the longest peptide, which is the only one to exhibit an alpha-helical structure in solution, could achieve DNA compacting before charge neutralisation.

Structural characterisation of the natural membrane-bound state of melittin: a fluorescence study of a dansylated analogue.

The binding of a dansylated analogue of melittin (DNC-melittin) to natural membranes is described. The cytolytic peptide from honey bee venom melittin was enzymatically labelled in its glutamine-25 with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase. The labelled peptide was characterised functionally in cytolytic assays, and spectroscopically by circular dichroism and fluorescence.

Bending elasticities of model membranes: influences of temperature and sterol content.

Giant liposomes obtained by electroformation and observed by phase-contrast video microscopy show spontaneous deformations originating from Brownian motion that are characterized, in the case of quasispherical vesicles, by two parameters only, the membrane tension sigma and the bending elasticity k(c). For liposomes containing dimyristoyl phosphatidylcholine (DMPC) or a 10 mol% cholesterol/DMPC mixture, the mechanical property of the membrane, k(c), is shown to be temperature dependent on approaching the main (thermotropic) phase transition temperature T(m). In the case of DMPC/cholesterol bilayers, we also obtained evidence for a relation between the bending elasticity and the corresponding temperature/cholesterol molecular ratio phase diagram.

In situ study by polarization modulated Fourier transform infrared spectroscopy of the structure and orientation of lipids and amphipathic peptides at the air-water interface.

Free amphipathic peptides and peptides bound to dimyristoylphosphatidylcholine (DMPC) were studied directly at the air/water interface using polarization modulation infrared reflection absorption spectroscopy (PMIRRAS). Such differential reflectivity measurements proved to be a sensitive and efficient technique to investigate in situ the respective conformations and orientations of lipid and peptide molecules in pure and mixed films. Data obtained for melittin, a natural hemolytic peptide, are compared to those of L15K7, an ideally amphipathic synthetic peptide constituted by only apolar Leu and polar Lys residues.

Ion channel formation by synthetic analogues of staphylococcal delta-toxin.

Ion channel formation by three analogues of staphylococcal delta-toxin, an amphipathic and alpha-helical channel-forming peptide, has been evaluated by measurement of ionic currents across planar lipid bilayers. Replacement of beta-branched, hydrophobic residues by leucine and movement of a tryptophan residue from the hydrophilic to the hydrophobic face of the helix does not significantly alter ion channel activity. Removal of the N-terminal blocking group combined with the substitution of glycine-10 by leucine changes the single channel properties of delta-toxin, without altering macroscopic conductance/voltage behaviour.

Evidence for a two-dimensional molecular lattice in subgel phase DPPC bilayers.

Using a combination of X-ray diffraction data from oriented films and multilamellar liposomes of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) in the subgel phase, we have established the presence of a 2D molecular lattice containing two lipid molecules. The proposed 2D lattice is consistent with all the X-ray diffraction data on the subgel phase of DPPC available in the literature. In this phase, the DPPC molecules are ordered in the plane of the bilayer and are also found to be positionally correlated across a single bilayer but not with those in adjacent bilayers.

Acyl chain length dependence in the stability of melittin-phosphatidylcholine complexes. A light scattering and 31P-NMR study.

Light scattering and 31P-NMR have been used to monitor the effect of the bee-toxin, melittin, on phosphatidylcholine (PC) bilayers of variable acyl chain length (from C16:0 to C20:0). Melittin interacts with all lipids provided the interaction is initiated in the lipid fluid phase. For low-to-moderate amounts of toxin (lipid-peptide molar ratios, Ri > or = 15), the system takes the form of large spheroidal vesicles, in the fluid phase, whose radius increases from 750 A with dipalmitoyl-PC (DPPC) to 1500 A with diarachinoyl-PC (DAPC).

The amphipathic alpha-helix concept. Application to the de novo design of ideally amphipathic Leu, Lys peptides with hemolytic activity higher than that of melittin.

An original series of 12- to 22-residue-long peptides was developed, they are only constituted by apolar Leu and charged Lys residues periodically located in the sequence in order to general ideal highly amphipathic alpha-helices. By circular dichroism, the peptides are proven to be mainly alpha-helical in organic and aqueous solvents and in the presence of lipids. The peptides are highly hemolytic, their activity varies according to the peptide length.

High-performance liquid chromatographic separation of modified and native melittin following transglutaminase-mediated derivatization with a dansyl fluorescent probe.

The 26-amino acid linear, amphiphilic peptide melittin was enzymatically modified with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase and a fluorescent derivative of stoichiometry 1:1 was obtained. Reversed-phase and size-exclusion high-performance liquid chromatographic modes were tested in order to resolve the labelled peptide and native species. The influence of several operational variables was analysed and the elution conditions were optimized so that a satisfactory resolution could be achieved in both instances in a rapid, easy manner.