High-Resolution Ultrasound Imaging System for the Evaluation of the Vascular Response to Stent or Balloon Injuries in the Rabbit Iliac Arteries

For novel therapeutic approaches of cardiovascular diseases, the preclinical investigation is of paramount and required appropriate technologies. We investigated the use of high-resolution ultrasound imaging system to evaluate the progression of vascular lesions in a rabbit model. Animals underwent vascular injury using two standard procedures. A bare-metal stent was placed within the left iliac artery, and a balloon injury was induced in the contralateral artery. The animals were kept on a regular diet for 8 weeks. A Vevo3100© VisualSonic high-resolution ultrasound imaging system and the associated software VevoVasc were used for the longitudinal evaluation of the injured arteries and the distal abdominal aorta. The lumen size increased rapidly after the intervention in both iliac arteries. In the balloon-injured artery, the augmentation was transient and significantly reversed, inducing an alteration of the blow flow. In contrast, in the stented segment, the lumen size was maintained enlarged overtime. We demonstrated a significant correlation for the wall thickness and the lumen size between ultrasonic and histological quantification. High-resolution ultrasound imaging in rabbit iliac arteries and the distal abdominal aorta is feasible, reliable and of relevance to investigate novel strategies for the inhibition of hyperplasia induced with standard injury models

Subsurface ablation of atherosclerotic plaque using ultrafast laser pulses

We perform subsurface ablation of atherosclerotic plaque using ultrafast pulses. Excised mouse aortas containing atherosclerotic plaque were ablated with ultrafast near-infrared (NIR) laser pulses. Optical coherence tomography (OCT) was used to observe the ablation result, while the physical damage was inspected in histological sections. We characterize the effects of incident pulse energy on surface damage, ablation hole size, and filament propagation. We find that it is possible to ablate plaque just below the surface without causing surface damage, which motivates further investigation of ultrafast ablation for subsurface atherosclerotic plaque removal

Ultrafast laser ablation for targeted atherosclerotic plaque removal

Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber

Une note sur le passage à l’échelle parallèle des solveurs linéaires de Poisson numériquement scalables

In the context of a parallel plasma physics simulation code, we perform a qualitativeperformance study between two natural candidates for the parallel solution of 3D Poisson problemsthat are multigrid and domain decomposition. We selected one representative of each of thesenumerical techniques implemented in state of the art parallel packages and show that dependingon the regime used in terms of number of unknowns per computing cores the best alternative interms of time to solution varies. Those results show the interest of having both types of numericalsolvers integrated in a simulation code that can be used in very different configurations in termsof selected modelisations, problem sizes and parallel computing platforms.Dans le contexte d’un code de simulation parallèle de la physique des plasmas, nous effectuons une étude qualitative des performances entre deux candidats naturels pour la résolution parallèle de problèmes de Poisson en 3D que sont les méthodes multigrilles et les méthodes de décomposition de domaine. Nous avons sélectionné un représentant de chacune de ces techniques numériques implémentées dans des progiciels parallèles de pointe. Nous montrons que selon le régime utilisé en termes de nombre d’inconnues par cœurs de calcul la meilleure alternative en termes de temps de résolution varie. Ces résultats montrent l’intérêt de disposer de ces deux types de solveurs numériques intégrés pour de la simulation intensive qui peut être utilisée dans des configurations très différentes en termes de modélisations choisies, taille des problèmes et plates-formes de calcul haute performance

Intra-Arterial Drug and Light Delivery for Photodynamic Therapy Using Visudyne (R): Implication for Atherosclerotic Plaque Treatment

Photodynamic therapy (PDT), which is based on the activation of photosensitizers with light, can be used to reduce plaque burden. We hypothesized that intra-arterial photosensitizer administration and photo-activation will lead to high and rapid accumulation within the plaque with reduced systemic adverse effects. Thus, this intra-arterial PDT would be expected to have less side effects and due to the short time involved would be compatible with percutaneous coronary interventions. Aim: We characterized the dose-dependent uptake and efficacy of intra-arterial PDT using Liposomal Verteporfin (Visudyne (R)), efficient for cancer-PDT but not tested before for PDT of atherosclerosis. Methods and Results: Visudyne (R) (100, 200, and 500 ng/ml) was perfused for 530 min in atherosclerotic aorta isolated from ApoE(-/-) mice. The fluorescence Intensity (FI) after 15 min of Visudyne (R) perfusion increased with doses of 100 (FI-5.5 +/- 1.8), 200 (FI-31.9 +/- 1.9) or 500 ng/ml (FI-42.9 +/- 1.2). Visudyne (R) (500 ng/ml) uptake also increased with the administration time from 5 min (FI-9.8 +/- 2.5) to 10 min (FI-23.3 +/- 3.0) and 15 min (FI-42.9 +/- 3.4) before reaching saturation at 30 min (FI-39.3 +/- 2.4) contact. Intra-arterial PDT (Fluence: 100 and 200 J/cm(2), irradiance-334 mW/cm(2)) was applied immediately after Visudyne (R) perfusion (500 ng/ml for 15 min) using a cylindrical light diffuser coupled to a diode laser (690 nm). PDT led to an increase of ROS (Dihydroethidium; FI-6.9 +/- 1.8, 25.3 +/- 5.5, 43.4 +/- 13.9) and apoptotic cells (TUNEL; 2.5 +/- 1.6, 41.3 +/- 15.3, 58.9 +/- 6%), mainly plaque macrophages (immunostaining; 0.3 +/- 0.2, 37.6 +/- 6.4, 45.3 +/- 5.4%) respectively without laser irradiation, or at 100 and 200 J/cm2. Limited apoptosis was observed in the medial wall (0.5 +/- 0.2, 8.5 +/- 4.7, 15.3 +/- 12.7%). Finally, Visudyne (R)-PDT was found to be associated with reduced vessel functionality (Myogram). Conclusion: We demonstrated that sufficient accumulation of Visudyne (R) within plaque could be achieved in short-time and therefore validated the feasibility of local intravascular administration of photosensitizer. Intra-arterial Visudyne (R)-PDT preferentially affected plaque macrophages and may therefore alter the dynamic progression of plaque development

Bereziskii-Kosterlitz-Thouless transition in the Weyl system \ce{PtBi2}

Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal \ce{PtBi2} lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality \ce{PtBi2} crystals are three-dimensional superconductors ($T_\text{c}\simeq$600~mK) with an isotropic critical field ($B_\text{c}\simeq$50~mT). Remarkably, we evidence in a rather thick flake (60~nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature $T_\text{c}\simeq 370$~mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with $T_\text{BKT}\simeq 310$~mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length $\xi$ in \ce{PtBi2}, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making \ce{PtBi2} an ideal platform to study low dimensional superconductivity in a topological semimetal

AFF3CT : Un environnement de simulation pour le codage de canal

International audienceDans cet article nous présentons un environne-ment de simulation de Monte Carlo pour les systèmes de communications numériques. Nous nous focalisons en particulier sur les fonctions associées au codage de canal. Après avoir présenté les enjeux liés à la simulation , nous identifions trois problèmes inhérents à ce type de simulation. Puis nous présentons les princi-pales caractéristiques de l'environnement AFF3CT

Overview of medical errors and adverse events

Safety is a global concept that encompasses efficiency, security of care, reactivity of caregivers, and satisfaction of patients and relatives. Patient safety has emerged as a major target for healthcare improvement. Quality assurance is a complex task, and patients in the intensive care unit (ICU) are more likely than other hospitalized patients to experience medical errors, due to the complexity of their conditions, need for urgent interventions, and considerable workload fluctuation. Medication errors are the most common medical errors and can induce adverse events. Two approaches are available for evaluating and improving quality-of-care: the room-for-improvement model, in which problems are identified, plans are made to resolve them, and the results of the plans are measured; and the monitoring model, in which quality indicators are defined as relevant to potential problems and then monitored periodically. Indicators that reflect structures, processes, or outcomes have been developed by medical societies. Surveillance of these indicators is organized at the hospital or national level. Using a combination of methods improves the results. Errors are caused by combinations of human factors and system factors, and information must be obtained on how people make errors in the ICU environment. Preventive strategies are more likely to be effective if they rely on a system-based approach, in which organizational flaws are remedied, rather than a human-based approach of encouraging people not to make errors. The development of a safety culture in the ICU is crucial to effective prevention and should occur before the evaluation of safety programs, which are more likely to be effective when they involve bundles of measures