Single NanoParticle Photothermal Tracking (SNaPT) of 5 nm gold beads in live cells

Tracking individual nano-objets in live cells during arbitrary long times is an ubiquitous need in modern biology. We present here a method for tracking individual 5 nm gold nanoparticles on live cells. It relies on the photothermal effect and the detection of the Laser Induced Scattering around a NanoAbsorber (LISNA). The key point for recording trajectories at video rate is the use of a triangulation procedure. The effectiveness of the method is tested against Single fluorescent Molecule Tracking in live COS7 cells on subsecond time scales. We further demonstrate recordings for several minutes of AMPA receptors trajectories on the plasma membrane of live neurons. SNaPT has the unique potential to record arbitrary long trajectory of membrane proteins using non-fluorescent nanometer sized labels

Pseudocontinuous arterial spin labeling reveals dissociable effects of morphine and alcohol on regional cerebral blood flow

We have examined sensitivity and specificity of pseudocontinuous arterial spin labeling (PCASL) to detect global and regional changes in cerebral blood flow (CBF) in response to two different psychoactive drugs. We tested alcohol and morphine in a placebo-controlled, double-blind randomized study in 12 healthy young men. Drugs were administered intravenously. Validated pharmacokinetic protocols achieved minimal intersubject and intrasubject variance in plasma drug concentration. Permutation-based statistical testing of a mixed effect repeated measures model revealed a widespread increase in absolute CBF because of both morphine and alcohol. Conjunction analysis revealed overlapping effects of morphine and alcohol on absolute CBF in the left anterior cingulate, right hippocampus, right insula, and left primary sensorimotor areas. Effects of morphine and alcohol on relative CBF (obtained from z-normalization of absolute CBF maps) were significantly different in the left putamen, left frontoparietal network, cerebellum, and the brainstem. Corroborating previous PET results, our findings suggest that PCASL is a promising tool for central nervous system drug research

Super-Resolution Dynamic Imaging of Dendritic Spines Using a Low-Affinity Photoconvertible Actin Probe

The actin cytoskeleton of dendritic spines plays a key role in morphological aspects of synaptic plasticity. The detailed analysis of the spine structure and dynamics in live neurons, however, has been hampered by the diffraction-limited resolution of conventional fluorescence microscopy. The advent of nanoscopic imaging techniques thus holds great promise for the study of these processes. We implemented a strategy for the visualization of morphological changes of dendritic spines over tens of minutes at a lateral resolution of 25 to 65 nm. We have generated a low-affinity photoconvertible probe, capable of reversibly binding to actin and thus allowing long-term photoactivated localization microscopy of the spine cytoskeleton. Using this approach, we resolve structural parameters of spines and record their long-term dynamics at a temporal resolution below one minute. Furthermore, we have determined changes in the spine morphology in response to pharmacologically induced synaptic activity and quantified the actin redistribution underlying these changes. By combining PALM imaging with quantum dot tracking, we could also simultaneously visualize the cytoskeleton and the spine membrane, allowing us to record complementary information on the morphological changes of the spines at super-resolution

CBCT et Spark

Le système Spark® est un système d’aligneurs permettant l’intégration d’images Cone-Beam (CBCT) en plus d’empreintes optiques, ce qui permet une meilleure précision dans le diagnostic et l’élaboration des plans de traitements par aligneurs. L’intégration et l’utilisation de ce système seront détaillées et illustrées à l’aide d’exemples cliniques, permettant de mieux appréhender cette nouvelle technologie et les possibilités offertes par ce système

Rôle de l'orthodontiste dans la prise en charge du syndrome des apnées obstructives du sommeil

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

Anomalies de structures dentaires (prise en charge orthodontique)

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

Vadose zone characterisation at industrial contaminated sites

An important challenge faced by environmental practitioners is the estimation of the impact of contamination that is transported from the source of contamination to soil and groundwater at industrial sites. Specifically, quantification of contaminant flux in the vadose zone is challenging due partly to the heterogeneity of the complex porous medium and the preferential flow. Contaminant flux estimations are essential to better establish risk assessment of soil and groundwater as well as to support the selection of remedial measures. Several methods have been developed for contaminant flux estimations in the vadose zone. These methodologies are either based on modelling, on experimental approaches, or on the combination of both, and have been developed principally in the context of agricultural purposes. However, the applicability of such techniques is questioned when it comes to their application to industrial sites, due to differences in depth of investigation, soil origin, contamination and sources. An overview of contaminant flux measurement techniques, together with a potential alternative for improving characterisation techniques and contaminant flux measurement in the vadose zone is presented in this bulletin. The vadose zone experimental setup consists of the combination of the Vadose Zone Monitoring System (VMS) and cross-hole geophysics

Initial data-sets from field experiments on contaminant mass transport and attenuation in the combined soil - vadose zone - groundwater system

In this report, a new system for vadose zone characterization is presented. The Vadose Zone Monitoring System (VMS) allows continuous measurements of water content throughout the vadose zone. In addition, soil water samples can be retrieved at different depths. Such technology is combined with cross-hole geophysics, providing a robust method for subsoil characterization

Monitored tracer experiment using the vadose zone experimental setup (VZES) for studying water and pollutant recharge processes in a brownfield

Contaminant transport characterization in the vadose zone of industrial contaminated sites requires in situ technologies that provide information representative of complex heterogeneous systems. However, finding the appropriate methodology is a challenge, as there is a risk of losing data resolution when capturing the spatial variability of the subsurface. An alternative method is provided by The Vadose Zone Experimental Setup (VZES) which combines surface and cross-borehole geophysical methods with a vadose zone monitoring system (VMS). When geophysical imaging is combined with in-situ hydraulic and chemical information at multiple depths of the vadose zone, detailed characterization of contaminant transport in heterogeneous systems is obtained. The system was installed at an industrial contaminated site in Belgium. A saline tracer infiltration test was performed over a heterogeneous vadose zone composed of backfilled materials underlined by unsaturated fractured chalk. Surface and cross-hole Electrical Resistivity Tomography (ERT) measurements were carried out over a 5 day period, following tracer injection. Results from time-lapse imaging reveal high resistivity variations at 0-0.5m depth, indicating that most of the tracer remained in the upper backfilled deposits. This is coincident with the results from sampled waters across the vadose zone, as no tracer was detected below 0.5m depth. Lower resistivity differences were observed laterally, indicating tracer migration in different directions via preferential flow paths. Lateral migration was found to be dominant over vertical transport in the absence of rain events. Three months after the injection, a geophysical survey was performed and combined with in situ continuous hydraulic and chemical information at multiple depths of the vadose zone. Results from geophysical imaging and water sample analyses indicate vertical movement of the tracer, which reached 4 m depth. Information obtained from continuous measurements of water content reveal that the tracer was transferred via preferential flow. The activation of such flow mechanism occurred as a response to rainfall episodes, resulting in water percolation and tracer transport towards higher depths. The results of the investigations demonstrate that the VZES is an effective method in identifying pathways and mechanisms of transport within a heterogeneous conductivity fields. The implementation of this methodological concept at industrial contaminated sites contributes to improve the development of site conceptual models for soil and groundwater protection and remediation