A two-tiered mechanism for stabilization and immobilization of E-cadherin.

Epithelial tissues maintain a robust architecture which is important for their barrier function, but they are also remodelled through the reorganization of cell-cell contacts. Tissue stability requires intercellular adhesion mediated by E-cadherin, in particular its trans-association in homophilic complexes supported by actin filaments through beta- and alpha-catenin. How alpha-catenin dynamic interactions between E-cadherin/beta-catenin and cortical actin control both stability and remodelling of adhesion is unclear.

Detection of emergency vehicles: driver responses to advance warning in a driving simulator.

Objective: This research evaluated the effects of an advance warning device (AWD) on the safety of driver interactions with emergency vehicles (EVs). The AWD was intended to provide drivers with advance warning of an approaching on-call EV via visual and auditory warnings when the EV was within a 300- to 400-m radius.

Background: Research suggests that drivers can experience difficulty accurately detecting the distance and direction of approaching on-call EV.

Jr-ZFP2, encoding a Cys2/His2-type transcription factor, is involved in the early stages of the mechano-perception pathway and specifically expressed in mechanically stimulated tissues in woody plants.

Plants respond to environmental mechanical stimulation, such as wind, by modifying their growth and development. To study the molecular effects of stem bending on 3-week-old walnut trees, a cDNA-AFLP approach was developed. This study allowed the identification of a cDNA, known as Jr-ZFP2, encoding a Cys2/His2-type two-zinc-fingered transcription factor.

Cell surface mechanics and the control of cell shape, tissue patterns and morphogenesis.

Embryonic morphogenesis requires the execution of complex mechanisms that regulate the local behaviour of groups of cells. The orchestration of such mechanisms has been mainly deciphered through the identification of conserved families of signalling pathways that spatially and temporally control cell behaviour. However, how this information is processed to control cell shape and cell dynamics is an open area of investigation.

Polysialylation increases lateral diffusion of neural cell adhesion molecule in the cell membrane.

Polysialic acid (PSA) is a polymer of N-acetylneuraminic acid residues added post-translationally to the membrane-bound neural cell adhesion molecule (NCAM). The large excluded volume created by PSA polymer is thought to facilitate cell migration by decreasing cell adhesion. Here we used live cell imaging (spot fluorescence recovery after photobleaching and fluorescence correlation spectroscopy) combined with biochemical approaches in an attempt to uncover a link between cell motility and the impact of polysialylation on NCAM dynamics.

How much solute is needed to inhibit the fluid to gel membrane phase transition at low hydration?

We present a quantitative study of the effect of sugars on the membrane gel-fluid phase transition as a function of sugar:lipid ratio. We show that the maximum effect occurs at around 1.5 sugar rings per molecule for both mono- and di-saccharides.

Single-scattering theory of light diffraction by a circular subwavelength aperture in a finitely conducting screen.

A perturbation theory based on a single-scattering approximation is developed from the rigorous differential theory of diffraction in cylindrical coordinates. It results in analytical formulas in the inverse space for the field amplitudes providing results that are in quantitative agreement with the results of the rigorous method, in both the near- and far-field regions, when a proper correction to the incident field inside the aperture is made by using the renormalized Born approximation. When working in reflection by a screen having permittivity high in modulus, the method proposes an equivalence with the simple model consisting of the emission by a single magnetic dipole excited inside the pierced layer, emission that is then transferred back into the cladding following the Fresnel's coefficients of transmission from the layer into the cladding.

Traffic signal phasing at intersections to improve safety for alcohol-affected pedestrians.

Alcohol-affected pedestrians are among the highest-risk groups involved in pedestrian casualty crashes. This paper investigates the opportunities to use a modified form of traffic signal operation during high-risk periods and at high-risk locations to reduce alcohol-affected pedestrian crashes and the severity of injuries that might otherwise occur. The 'Dwell-on-Red' treatment involves displaying a red traffic signal to all vehicle directions during periods when no vehicular traffic is detected, so that drivers approach high-risk intersections at a lower speed than if a green signal were displayed.

Dual-color fluorescence cross-correlation spectroscopy in a single nanoaperture : towards rapid multicomponent screening at high concentrations.

Single nanometric apertures in a metallic film are used to develop a simple and robust setup for dual-color fluorescence cross-correlation spectroscopy (FCCS) at high concentrations. If the nanoaperture concept has already proven to be useful for single-species analysis, its extension to the dual-color case brings new interesting specificities. The alignment and overlap of the two excitation beams are greatly simplified.

Diffusion analysis within single nanometric apertures reveals the ultrafine cell membrane organization.

We describe the development of a new methodology to probe the plasma membrane organization of living cells at the nanometric scale. Single nanometric apertures in a metallic film limit the observed membrane area below the optical diffraction barrier. The new approach performs fluorescence correlation spectroscopy with increasing aperture sizes and extracts information on the diffusion process from the whole set of data.

V180I mutation of the prion protein gene associated with atypical PrPSc glycosylation.

A valine to isoleucine mutation at residue 180 was identified in a French patient with Creutzfeldt-Jakob disease (CJD). The mutation is located in the close vicinity of one of the two N-glycosylation sites of the cellular prion protein (PrP(C)). Western blot analysis revealed accumulation in the brain of the pathogenic proteinase K-resistant PrP (PrP(Sc)) isoform with the notable absence of the diglycosylated band.

Posture control and skeletal mechanical acclimation in terrestrial plants: implications for mechanical modeling of plant architecture.

Self-supporting plant stems are slender, erect structures that remain standing while growing in highly variable mechanical environments. Such ability is not merely related to an adapted mechanical design in terms of material-specific stiffness and stem tapering. As many terrestrial standing animals do, plant stems regulate posture through active and coordinated control of motor systems and acclimate their skeletal growth to prevailing loads.

Refractive effects in coherent anti-Stokes Raman scattering microscopy.

Coherent anti-Stokes Raman scattering (CARS) microscopy with high sensitivity and high three- dimensional resolution has been developed for the vibrational imaging of chemical species. Due to the coherent nature of the CARS emission, it has been reported that the detection of epi-CARS and forward-CARS (F-CARS) signals depends on the size and shape of the sample. We investigate theoretically and experimentally the effects on the CARS signal of refractive index mismatches between the sample and its surroundings.

Field enhancement in single subwavelength apertures.

A peak of the detected fluorescence rate per molecule has recently been observed in experiments of fluorescence correlation spectroscopy carried out on subwavelength apertures in metallic screens, a phenomenon that appears at a diameter-to-wavelength ratio below the fundamental mode cutoff. Although the origin of the resonant transmission through a subwavelength aperture has been well explained in terms of excitation of plasmon surface modes on the aperture ridge, the origin of the maximum that occurs at a radius-to-wavelength ratio smaller than 1/4 was not clear. Using a rigorous electromagnetic theory of light diffraction in cylindrical geometry, we show that it is linked to the appearance of the fundamental mode propagating inside the aperture.

Dynamics in the plasma membrane: how to combine fluidity and order.

Cell membranes are fascinating supramolecular aggregates that not only form a barrier between compartments but also harbor many chemical reactions essential to the existence and functioning of a cell. Here, it is proposed to review the molecular dynamics and mosaic organization of the plasma membrane, which are thought to have important functional implications. We will first summarize the basic concepts of Brownian diffusion and lipid domain formation in model membranes and then track the development of ideas and tools in this field, outlining key results obtained on the dynamic processes at work in membrane structure and assembly.

Economic evaluation of varicella vaccination in Spain: results from a dynamic model.

Varicella is a universal childhood disease in Spain, causing approximately 400,000 cases, 1,500 hospitalizations and 15 deaths every year. The aim of this study is to determine the economic impact of childhood varicella vaccination on the burden of disease and associated costs by using a dynamic model. The analysis is based on the varicella transmission model developed by Halloran and adapted to the Spanish context.

Dynamic molecular confinement in the plasma membrane by microdomains and the cytoskeleton meshwork.

It is by now widely recognized that cell membranes show complex patterns of lateral organization. Two mechanisms involving either a lipid-dependent (microdomain model) or cytoskeleton-based (meshwork model) process are thought to be responsible for these plasma membrane organizations. In the present study, fluorescence correlation spectroscopy measurements on various spatial scales were performed in order to directly identify and characterize these two processes in live cells with a high temporal resolution, without any loss of spatial information.

Confined diffusion in tubular structures analyzed by fluorescence correlation spectroscopy on a mirror.

In fluorescence correlation spectroscopy (FCS) analysis it is generally assumed that molecular species diffuse freely in volumes much larger than the three-dimensional FCS observation volume. However, this standard assumption is not valid in many measurement conditions, particularly in tubular structures with diameters in the micrometer range, such as those found in living cells (organelles, dendrites) and microfluidic devices (capillaries, reaction chambers). As a result the measured autocorrelation functions (ACFs) deviate from those predicted for free diffusion, and this can shift the measured diffusion coefficient by as much as ~50% when the tube diameter is comparable with the axial extension of the FCS observation volume.

Effect of opioid substitution therapy on alcohol metabolism.

Forty opioid substitution patients (methadone, n = 14; LAAM, n = 14; and buprenorphine, n = 12) who were participating in a study on the impact of opiate substitution treatment on driving ability and 22 non-opiate-using control subjects were administered 14.7 g/70 kg of alcohol in two separate sessions, one 2-3 hours before opioid pharmacotherapy dosing and the other 1-2 hours after dosing. The mean blood alcohol concentration (BAC) in the post-opioid dose session was significantly lower than that in the pre-opioid dose session (p < .

Single-fluorophore diffusion in a lipid membrane over a subwavelength aperture.

We use submicrometer apertures milled in an aluminium film to study the diffusion dynamics of beta-Bodipy-FL-C(5)-HPC (Bodipy-PC) fluorophores in a lipid dioleoylphosphatidylcholine (DOPC) multilayer. The observation volume is limited by the aperture diameter, well below the optical wavelength. This spatial resolution improvement comes together with an enhancement of the detected fluorescence per molecule as compared to an open sample, with a significant increase up to 3.

Fluorescence correlation spectroscopy diffusion laws to probe the submicron cell membrane organization.

To probe the complexity of the cell membrane organization and dynamics, it is important to obtain simple physical observables from experiments on live cells. Here we show that fluorescence correlation spectroscopy (FCS) measurements at different spatial scales enable distinguishing between different submicron confinement models. By plotting the diffusion time versus the transverse area of the confocal volume, we introduce the so-called FCS diffusion law, which is the key concept throughout this article.

Enhancement of single-molecule fluorescence detection in subwavelength apertures.

We report the experimental proof of molecular count rate enhancement (up to 6.5-fold) and lifetime reduction for single fluorescent molecules diffusing in subwavelength apertures milled in aluminum films. The observed enhancement dependence with the aperture diameter agrees qualitatively with numerical electromagnetic computations of the excitation power density into the aperture volume.

Single molecule fluorescence in rectangular nano-apertures.

Fluorescence Correlation Spectroscopy is used to investigate fluorescent molecules in solution diffusing in subwavelength rectangular apertures milled in Aluminium films. This rectangular shape allows to switch between a propagating and an evanescent excitation field within the aperture, leading to a significant tunability of the observation volume. Due to the vicinity of the metal surface, the fluorophore's molecular lifetime inside the aperture appears to be dramatically reduced whatever the excitation field is set to.