A discontinuous Galerkin method for elliptic interface problems with application to electroporation

Guyomarc'h, Gré,gory,Lee, Chang-Ock,Jeon, Kiwan John Wiley Sons, Ltd. 2009 Communications in numerical methods in engineering Vol.25 No.10

<P>We solve elliptic interface problems using a discontinuous Galerkin (DG) method, for which discontinuities in the solution and in its normal derivatives are prescribed on an interface inside the domain. Standard ways to solve interface problems with finite element methods consist in enforcing the prescribed discontinuity of the solution in the finite element space. Here, we show that the DG method provides a natural framework to enforce both discontinuities weakly in the DG formulation, provided the triangulation of the domain is fitted to the interface. The resulting discretization leads to a symmetric system that can be efficiently solved with standard algorithms. The method is shown to be optimally convergent in the L<SUP>2</SUP>-norm. We apply our method to the numerical study of electroporation, a widely used medical technique with applications to gene therapy and cancer treatment. Mathematical models of electroporation involve elliptic problems with dynamic interface conditions. We discretize such problems into a sequence of elliptic interface problems that can be solved by our method. We obtain numerical results that agree with known exact solutions. Copyright © 2008 John Wiley & Sons, Ltd.</P>

Local Control of the <i>Cis</i>–<i>Trans</i> Isomerization and Backbone Dihedral Angles in Peptides Using Trifluoromethylated Pseudoprolines

Feytens, Debby,Chaume, Gré,gory,Chassaing, Gé,rard,Lavielle, Solange,Brigaud, Thierry,Byun, Byung Jin,Kang, Young Kee,Miclet, Emeric American Chemical Society 2012 The Journal of physical chemistry B Vol.116 No.13

<P>NMR studies and theoretical calculations have been performed on model peptides Ac-Ser(ΨPro)-NHMe, (<I>S</I>,<I>S</I>)Ac-Ser(Ψ<SUP>H,CF3</SUP>Pro)-NHMe, and (<I>R,S</I>)Ac-Ser(Ψ<SUP>CF3,H</SUP>Pro)-NHMe. Their thermodynamic and kinetic features have been analyzed in chloroform, DMSO, and water, allowing a precise description of their conformational properties. We found that trifluoromethyl C<SUP>δ</SUP>-substitutions of oxazolidine-based pseudoprolines can strongly influence the <I>cis</I>–<I>trans</I> rotational barriers with only moderate effects on the <I>cis</I>/<I>trans</I> population ratio. In CHCl<SUB>3</SUB>, the configuration of the CF<SUB>3</SUB>–C<SUP>δ</SUP> entirely controls the ψ-dihedral angle, allowing the stabilization of γ-turn-like or PPI/PPII-like backbone conformations. Moreover, in water and DMSO, this C<SUP>δ</SUP>-configuration can be used to efficiently constrain the ring puckering without affecting the <I>cis</I>/<I>trans</I> population ratio. Theoretical calculations have ascertained the electronic and geometric properties induced by the trifluoromethyl substituent and provided a rational understanding of the NMR observations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2012/jpcbfk.2012.116.issue-13/jp300284u/production/images/medium/jp-2012-00284u_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp300284u'>ACS Electronic Supporting Info</A></P>

Susceptibility Vessel Sign in the ASTER Trial: Higher Recanalization Rate and More Favourable Clinical Outcome after First Line Stent Retriever Compared to Contact Aspiration

Romain Bourcier,Mickael Mazighi,Julien Labreuche,Robert Fahed,Raphael Blanc,Benjamin Gory,Alain Duhamel,Gaultier Marnat,Suzana Saleme,Vincent Costalat,Serge Bracard,Hubert Desal,Arturo Consoli,Michel 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.2

Background and Purpose In the Aspiration vs. Stent Retriever for Successful Revascularization (ASTER) trial, which evaluated contact aspiration (CA) versus stent retriever (SR) use as first-line technique, the impact of the susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) was studied to determine its influence on trial results. Methods We included patients having undergone CA or SR for M1 or M2 occlusions, who were screened by MRI with T2* gradient recalled echo. Occlusions were classified as SVS (+) or SVS (–) in each randomization arm. Modified thrombolysis in cerebral infarction (mTICI) 2b, 2c, or 3 revascularization rates were recorded and clinical outcomes assessed by the overall distribution of modified Rankin scale (mRS) at 90 days. Results Among the 202 patients included, 143 patients were SVS (+) (70.8%; 95% confidence interval [CI], 64.5% to 77.1%). Overall, there was no difference in angiographic and clinical outcomes according to SVS status. However, compared to SR, CA achieved a lower mTICI 2c/3 rate in SVS (+) patients (risk ratio [RR] for CA vs. SR, 0.60; 95% CI, 0.51 to 0.71) but not in SVS (–) (RR, 1.11; 95% CI, 0.69 to 1.77; P for interaction=0.018). A significant heterogeneity in favor of superiority of first-line SR strategy in SVS (+) patients was also found regarding the overall mRS distribution (common odds ratio for CA vs. SR, 0.40 vs. 1.32; 95% CI, 0.21 to 0.74 in SVS (+) vs. 95% CI, 0.51 to 3.35 in SVS (–); P for interaction=0.038). Conclusions As a first line strategy, SR achieved higher recanalization rates and a more favourable clinical outcome at 3 months compared to CA when MRI shows SVS within the thrombus.

ERRATUM: Corrected Error in Table Susceptibility Vessel Sign in the ASTER Trial: Higher Recanalization Rate and More Favourable Clinical Outcome after First Line Stent Retriever Compared to Contact Aspiration

Romain Bourcier,Mickael Mazighi,Julien Labreuche,Robert Fahed,Raphael Blanc,Benjamin Gory,Alain Duhamel,Gaultier Marnat,Suzana Saleme,Vincent Costalat,Serge Bracard,Hubert Desal,Arturo Consoli,Michel 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.3

Intravenous Thrombolysis Prior to Mechanical Thrombectomy in Acute Ischemic Stroke: Silver Bullet or Useless Bystander?

Federico Di Maria,Mikael Mazighi,Maéva Kyheng,Julien Labreuche,Georges Rodesch,Arturo Consoli,Oguzhan Coskun,Benjamin Gory,Bertrand Lapergue 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.3

Background and Purpose Recent single-center series and meta-analyses suggest that mechanical thrombectomy (MT) without prior intravenous thrombolysis (IVT) might be equally effective to bridging therapy. We analyzed, within the Endovascular Treatment in Ischemic Stroke (ETIS) prospective observational registry, the angiographic and clinical outcomes after IVT+MT versus MT alone. Methods From December 2012 to December 2016, a total of 1,507 consecutive patients with a proximal arterial occlusion of the anterior circulation were treated by MT. Of these, 975 (64.7%) received prior IVT. Immediate angiographic and clinical outcomes at 90 days (modified Rankin Scale [mRS]) were compared between the two groups while checking for propensity score, matchedpropensity score and by inverse probability of treatment weighting (IPTW) propensity score method. Results Favorable outcome (mRS 0 to 2) was more frequently achieved after IVT+MT (n=523, 53.6%) than after MT alone (n=222, 41.8%) with an unadjusted odds ratio (OR) for bridging therapy of 1.61 (95% confidence interval [CI], 1. 29 to 2.01). This difference remained not significant in matched-propensity score cohort (OR, 1.21; 95% CI, 0.90 to 1.63) although it remained according to adjusted propensity score (OR, 1.31; 95% CI, 1.02 to 1.68) and IPTW (OR, 1.37; 95% CI, 1.09 to 1.73) analyses. A significant difference was found in terms of excellent outcome (mRS 0 to 1) (adjusted OR, 1.63; 95% CI, 1.25 to 2.11) and successful reperfusion (adjusted OR, 1.58; 95% CI, 1.33 to 2.15). No differences in intracerebral hemorrhage or in allcause mortality within 90 days were found between groups. Conclusions IVT prior to MT is associated with increased excellent outcome and successful reperfusion rates. These findings support the use of bridging therapy.

Perfusion Imaging to Select Patients with Large Ischemic Core for Mechanical Thrombectomy

Basile Kerleroux,Kevin Janot,Cyril Dargazanli,Dimitri Daly-Eraya,Wagih Ben-Hassen,François Zhu,Benjamin Gory,Jean François Hak,Charline Perot,Lili Detraz,Romain Bourcier,Aymeric Rouchaud,Géraud Forest 대한뇌졸중학회 2020 Journal of stroke Vol.22 No.2

Background and Purpose Patients with acute ischemic stroke, proximal vessel occlusion and a large ischemic core at presentation are commonly not considered for mechanical thrombectomy (MT). We tested the hypothesis that in patients with baseline large infarct cores, identification of remaining penumbral tissue using perfusion imaging would translate to better outcomes after MT. Methods This was a multicenter, retrospective, core lab adjudicated, cohort study of adult patients with proximal vessel occlusion, a large ischemic core volume (diffusion weighted imaging volume ≥70 mL), with pre-treatment magnetic resonance imaging perfusion, treated with MT (2015 to 2018) or medical care alone (controls; before 2015). Primary outcome measure was 3-month favorable outcome (defined as a modified Rankin Scale of 0–3). Core perfusion mismatch ratio (CPMR) was defined as the volume of critically hypo-perfused tissue (Tmax >6 seconds) divided by the core volume. Multivariable logistic regression models were used to determine factors that were independently associated with clinical outcomes. Outputs are displayed as adjusted odds ratio (aOR) and 95% confidence interval (CI). Results A total of 172 patients were included (MT n=130; Control n=42; mean age 69.0±15.4 years; 36% females). Mean core-volume and CPMR were 102.3±36.7 and 1.8±0.7 mL, respectively. As hypothesized, receiving MT was associated with increased probability of favorable outcome and functional independence, as CPMR increased, a difference becoming statistically significant above a mismatch-ratio of 1.72. Similarly, receiving MT was also associated with favorable outcome in the subgroup of 74 patients with CPMR >1.7 (aOR, 8.12;95% CI, 1.24 to 53.11; P=0.028). Overall (prior to stratification by CPMR) 73 (42.4%) patients had a favorable outcome at 3 months, with no difference amongst groups. Conclusions In patients currently deemed ineligible for MT due to large infarct ischemic cores at baseline, CPMR identifies a subgroup strongly benefiting from MT. Prospective studies are warranted.

Metric Scale Study of the Bonded Concrete-Rock Interface Shear Behaviour

Marion Bost,Hussein Mouzannara,Fabrice Rojat,Grégory Coubard,Jean-Pierre Rajot 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.2

The shear strength of concrete-rock interface is a key factor to evaluate the stability of gravity dams. The shear strength assessment by achieving tests on small samples gives values different from those estimated by back-analysis on the existing dams. This work aims to study the shear behaviour of concrete-rock interface in the metric scale. Five direct shear tests were performed on bonded meter-scale concrete-granite interfaces in the range of normal stresses to which gravity dam foundation is subjected. Specific instrumentation were installed to monitor the failure mechanisms during the tests. The five concrete-rock interfaces have not broken by shearing of materials (concrete, rock) in the shear plane imposed by the test device, but by debonding of the contact between concrete and rock. Considering roughness of the contact surface in the decimeter scale and the results of shear tests carried out in the same scale, the decimeter scale is demonstrated to correspond to the elementary surface for the shear behaviour of the metric concrete-rock interface. According to the level of normal stress, the stiffness of both materials and the main asperities in the decimeter scale, different failure mechanisms occur locally to justify the overall failure in the metric scale.

Use of Denaturing High-Performance Liquid Chromatography (DHPLC) to Characterize the Bacterial and Fungal Airway Microbiota of Cystic Fibrosis Patients

Jérôme Mounier,Geneviève Héry-Arnaud,Audrey Gouëllo,Marlène Keravec,Solène Le Gal,Grégory Pacini,Stella Debaets,Gilles Nevez,Gilles Rault,Georges Barbier 한국미생물학회 2014 The journal of microbiology Vol.52 No.4

The aim of this study was to evaluate the use of denaturinghigh-performance liquid chromatography (DHPLC) to characterizecystic fibrosis (CF) airway microbiota includingboth bacteria and fungi. DHPLC conditions were first optimizedusing a mixture of V6, V7 and V8 region 16S rRNAgene PCR amplicons from 18 bacterial species commonlyfound in CF patients. Then, the microbial diversity of 4 sputumsamples from 4 CF patients was analyzed using culturalmethods, cloning/sequencing (for bacteria only) and DHPLCpeak fraction collection/sequencing. DHPLC analysis allowedidentifying more bacterial and fungal species than the classicalculture methods, including well-recognized pathogenssuch as Pseudomonas aeruginosa. Even if a lower number ofbacterial Operational Taxonomic Units (OTUs) was identifiedby DHPLC, it allowed to find OTUs unidentified bycloning/sequencing. The combination of both techniquespermitted to correlate the majority of DHPLC peaks to definedOTUs. Finally, although Aspergillus fumigatus detectionusing DHPLC can still be improved, this techniqueclearly allowed to identify a higher number of fungal speciesversus classical culture-based methods. To conclude, DHPLCprovided meaningful additional data concerning pathogenicbacteria and fungi as well as fastidious microorganisms presentwithin the CF respiratory tract. DHPLC can be consideredas a complementary technique to culture-dependentanalyses in routine microbiological laboratories.

Extracellular vesicle-based therapeutics: natural versus engineered targeting and trafficking

Daniel E. Murphy,Olivier G. de Jong,Maarten Brouwer,Matthew J. Wood,Grégory Lavieu,Raymond M. Schiffelers,Pieter Vader 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Extracellular vesicles (EVs) are increasingly being recognized as mediators of intercellular signaling via the delivery of effector molecules. Interestingly, certain types of EVs are also capable of inducing therapeutic responses. For these reasons, the therapeutic potential of EVs is a topic of intense research, both in the context of drug delivery and regenerative medicine. However, to fully utilize EVs for therapeutic purposes, an improved understanding of the mechanisms by which they function would be highly advantageous. Here, the current state of knowledge regarding the cellular uptake and trafficking of EVs is reviewed, along with a consideration of how these pathways potentially influence the functions of therapeutic EVs. Furthermore, the natural cell-targeting abilities, biodistribution profiles, and pharmacokinetics of exogenously administered EVs, along with the components responsible for these features are discussed. An overview of the potential clinical applications and preclinical examples of their successful use is also provided. Finally, examples of EV modifications that have successfully been employed to improve their therapeutic characteristics receive a particular focus. We suggest that, in addition to investigation of EV cell targeting and routes of uptake, future research into the routes of intracellular trafficking in recipient cells is required to optimally utilize EVs for therapeutic purposes.

Cornering electroweakinos at the LHC

Gori, Stefania,Jung, Sunghoon,Wang, Lian-Tao Springer-Verlag 2013 Journal of high energy physics Vol.2013 No.10