142 results on '"A, Eghiaian"'
Search Results
2. Insight into the PrP C → PrP Sc Conversion from the Structures of Antibody-Bound Ovine Prion Scrapie-Susceptibility Variants
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Eghiaian, Frédéric, Grosclaude, Jeanne, Lesceu, Stéphanie, Debey, Pascale, Doublet, Bénédicte, Tréguer, Eric, Rezaei, Human, Knossow, Marcel, and Eisenberg, David S.
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- 2004
3. End-Expiratory Occlusion Test to Predict Fluid Responsiveness Is Not Suitable for Laparotomic Surgery
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Weil, Gregoire, Motamed, Cyrus, Monnet, Xavier, Eghiaian, Alexandre, and Le Maho, Anne-Laure
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- 2020
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4. How to rationalize preoperative tests? A method to implement local guidelines successfully
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Suria, Stéphanie, Harkouk, Hakim, Eghiaian, Alexandre, and Weil, Grégoire
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- 2016
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5. Comparaison de quatre masques laryngés à usage unique pour la chirurgie carcinologique du sein : une approche médico-économique
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Weil, G., Matysiak, J., Guye, M.-L., Eghiaian, A., and Bourgain, J.-L.
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- 2014
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6. The use of a clinical database in an anesthesia unit: focus on its limits
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Weil, Grégoire, Motamed, Cyrus, Eghiaian, Alexandre, Guye, Marie Laurence, and Bourgain, Jean Louis
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- 2015
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7. End-Expiratory Occlusion Test to Predict Fluid Responsiveness Is Not Suitable for Laparotomic Surgery
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Xavier Monnet, Grégoire Weil, Cyrus Motamed, Anne-Laure Le Maho, and Alexandre Eghiaian
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Adult ,Male ,medicine.medical_specialty ,Time Factors ,Cardiac index ,Hemodynamics ,Predictive Value of Tests ,Monitoring, Intraoperative ,Intensive care ,Occlusion ,medicine ,Humans ,Infusions, Parenteral ,Prospective Studies ,Aged ,Laparotomy ,Receiver operating characteristic ,business.industry ,Reproducibility of Results ,Crystalloid Solutions ,Stroke volume ,Middle Aged ,Respiration, Artificial ,Surgery ,Pulse pressure ,Anesthesiology and Pain Medicine ,Predictive value of tests ,Fluid Therapy ,Female ,business - Abstract
BACKGROUND The end-expiratory occlusion test predicts fluid responsiveness in ventilated intensive care patients; however, its utility in the operating room is questioned. We assessed end-expiratory occlusion test in laparotomic surgery for predicting volume expansion. METHODS Forty-six patients were included in this study: stage 1 (n = 26) with an end-expiratory occlusion test of 15 seconds, followed by volume expansion, which consisted of 250 mL of colloid over 5 minutes and stage 2 (n = 20) with an end-expiratory occlusion test of 25 seconds followed by volume expansion. The last 10 patients had transdiaphragmatic pressures probed. Patients with an increase in cardiac index >15% after volume expansion were responders. Pulse pressure variation, stroke volume (SV) index, and cardiac index were analyzed. Receiver operating characteristic curves were established for changes in SV and pulse pressure induced by end-expiratory occlusion test and pulse pressure variation using the responders status for volume expansion as outcome. RESULTS A total of 44 (38%) volume expansions were deemed responders. After end-expiratory occlusion test of 15 seconds, no hemodynamic variables were significantly increased. After end-expiratory occlusion test of 25 seconds, SV index increased in responders (37.1 ± 8.8 mL/m after end-expiratory occlusion test of 25 seconds versus 35.7 ± 8.6 before; P < .0001). End-expiratory occlusion test could not discriminate responders from nonresponders. Only pulse pressure variation had significantly different area under the curve from that expected by chance (0.7 [0.57-0.81]; P = .002 for end-expiratory occlusion test of 15 seconds; and 0.78 [0.64-0.89]; P = .0001 for end-expiratory occlusion test of 25 seconds). After laparotomy, gastric pressure decreased significantly (4 [2.75-5] vs 2 [2-4] cm H2O; P = .0417); no difference was noticed in the transdiaphragmatic gradient. CONCLUSIONS End-expiratory occlusion test was not reliable to discriminate responders from nonresponders after volume expansion during laparotomic surgery.
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- 2020
8. Management and outcome of head and neck squamous cell carcinomas in obese patients
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Deneuve, S., Tan, H.K., Eghiaian, A., and Temam, S.
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- 2011
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9. Diversity in Prion Protein Oligomerization Pathways Results from Domain Expansion as Revealed by Hydrogen/Deuterium Exchange and Disulfide Linkage
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Eghiaian, Frederic, Daubenfeld, Thorsten, Quenet, Yann, van Audenhaege, Marieke, Bouin, Anne-Pascale, van der Rest, Guillaume, Grosclaude, Jeanne, and Rezaei, Human
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- 2007
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10. Comparison of Proaqt/Pulsioflex® and oesophageal Doppler for intraoperative haemodynamic monitoring during intermediate-risk abdominal surgery
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Stéphanie Suria, Xavier Monnet, Cyrus Motamed, Grégoire Weil, and Alexandre Eghiaian
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Cardiac output ,Receiver operating characteristic ,business.industry ,Concordance ,Area under the curve ,Cardiac index ,030208 emergency & critical care medicine ,General Medicine ,Stroke volume ,Critical Care and Intensive Care Medicine ,Pulse pressure ,03 medical and health sciences ,0302 clinical medicine ,Anesthesiology and Pain Medicine ,030202 anesthesiology ,Medicine ,business ,Nuclear medicine ,Abdominal surgery - Abstract
Objective To compare cardiac index (CI) between Proaqt/PulsioFlex® and oesophageal Doppler (OD) and the ability of the PulsioFlex® to track CI changes induced by fluid challenge and secondly to assess the impact of the time interval between two auto-calibrations of PulsioFlex® on the accuracy of the measured CI. Methods In a single hospital, 49 intermediate-risk oncologic abdominal surgery patients were included in an observational study. We measured the cardiac Index (CI) provided by OD and by the Proaqt/PulsioFlex® before and after internal calibration, which were performed randomly at specific intervals after the initial one (30, 60, 90 and 120 min). The ability to track fluid responsiveness was evaluated by measuring stroke volume variation, pulse pressure variation (PPV) and CI before and after a 250 ml fluid challenge and assessed by a receiver operating characteristic curve analysis. Results The percentages of error before calibration were 51, 58, 82, 81% for 30, 60, 90 and 120 min, they were 39, 57, 65, and 54% after calibration. Trending ability is assumed by a 93% concordance rate after applying a 15% exclusion zone. The trend interchangeability rate was 13.75%. The area under the curve for fluid responsiveness measured by PPV and SVV PulsioFlex were respectively 0.67 [0.57–0.77], P Conclusions The Proaqt/Pulsioflex® system is not equivalent to OD for haemodynamic monitoring during non-vascular abdominal surgery in intermediate-risk patients. More studies are required to define the effect of the auto-calibration on the system.
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- 2019
11. Measurement of cardiac index by transpulmonary thermodilution using an implanted central venous access port: a prospective study in patients scheduled for oncologic high-risk surgery.
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Stéphanie Suria, Anne Wyniecki, Alexandre Eghiaian, Xavier Monnet, and Grégoire Weil
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Medicine ,Science - Abstract
BACKGROUND:Transpulmonary thermodilution allows the measurement of cardiac index for high risk surgical patients. Oncologic patients often have a central venous access (port-a-catheter) for chronic treatment. The validity of the measurement by a port-a-catheter of the absolute cardiac index and the detection of changes in cardiac index induced by fluid challenge are unknown. METHODS:We conducted a monocentric prospective study. 27 patients were enrolled. 250 ml colloid volume expansions for fluid challenge were performed during ovarian cytoreductive surgery. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution by a central venous access (CIcvc) and by a port-a-catheter (CIport) were recorded. RESULTS:23 patients were analyzed with 123 pairs of measurements. Using a Bland and Altman for repeated measurements, the bias (lower and upper limits of agreement) between CIport and CIcvc was 0.14 (-0.59 to 0.88) L/min/m2. The percentage error was 22%. The concordance between the changes in CIport and CIcvc observed during volume expansion was 92% with an r = 0.7 (with exclusion zone). No complications (included sepsis) were observed during the follow up period. CONCLUSIONS:The transpulmonary thermodilution by a port-a-catheter is reliable for absolute values estimation of cardiac index and for measurement of the variation after fluid challenge. TRIAL REGISTRATION:clinicaltrials.gov NCT02063009.
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- 2014
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12. The detrimental invasiveness of glioma cells controlled by gadolinium chelate-coated gold nanoparticles
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Durand, Maxime, primary, Lelievre, Elodie, additional, Chateau, Alicia, additional, Berquand, Alexandre, additional, Laurent, Gautier, additional, Carl, Philippe, additional, Roux, Stéphane, additional, Chazee, Lise, additional, Bazzi, Rana, additional, Eghiaian, Frederic, additional, Jubreaux, Justine, additional, Ronde, Philippe, additional, Barberi-Heyob, Muriel, additional, Chastagner, Pascal, additional, Devy, Jérôme, additional, and Pinel, Sophie, additional
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- 2021
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13. Insight into the Pr[P.sup.c] [right arrow] Pr[P.sup.Sc] conversion from the structures of antibody-bound ovine prion scrapie-susceptibility variants
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Eghiaian, Frederic, Grosclaude, Jeanne, Lesceu, Stephanie, Debey, Pascale, Doublet, Benedicte, Treguer, Eric, Rezaei, Human, and Knossow, Marcel
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Prion diseases -- Research ,Science and technology ,National Academy of Sciences -- Research - Abstract
Prion diseases are associated with the conversion of the [alpha]-helix rich prion protein (Pr[P.sup.c]) into a [beta]-structure-rich insoluble conformer (Pr[P.sup.Sc]) that is thought to be infectious. The mechanism for the Pr[P.sup.c] [right arrow] Pr[P.sup.Sc] conversion and its relationship with the pathological effects of prion diseases are poorly understood, partly because of our limited knowledge of the structure of Pr[P.sup.Sc]. In particular, the way in which mutations in the PRNP gene yield variants that confer different susceptibilities to disease needs to be clarified. We report here the 2.5-A-resolution crystal structures of three scrapie-susceptibility ovine PrP variants complexed with an antibody that binds to Pr[P.sup.c] and to pr[p.sup.Sc]; they identify two important features of the Pr[P.sup.c] [right arrow] Pr[p.sup.Sc] conversion. First, the epitope of the antibody mainly consists of the last two turns of ovine PrP second [alpha]-helix. We show that this is a structural invariant in the Pr[P.sup.c] [right arrow] Pr[P.sup.Sc] conversion; taken together with biochemical data, this leads to a model of the conformational change in which the two Pr[P.sup.c] C-terminal [alpha]-helices are conserved in Pr[P.sup.So], whereas secondary structure changes are located in the N-terminal [alpha]-helix. Second, comparison of the structures of scrapie-sensitivity variants defines local changes in distant parts of the protein that account for the observed differences of Pr[P.sup.c] stability, resistant variants being destabilized compared with sensitive ones. Additive contributions of these sensitivity-modulating mutations to resistance suggest a possible causal relationship between scrapie resistance and lowered stability of the PrP protein.
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- 2004
14. Structural and Dynamic Characterization of Biochemical Processes by Atomic Force Microscopy
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Eghiaian, Frédéric, primary and Schaap, Iwan A. T., additional
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- 2011
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15. Lien entre type génétique et résistance des ovins à la Tremblante : une approche structurale et physico-chimique
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H. REZAEI, J. GROSCLAUDE, F. EGHIAIAN, T. HAERTLE, M. MARDEN, M. KNOSSOW, and P. DEBEY
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Animal culture ,SF1-1100 ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
Le polymorphisme génétique de la protéine prion ovine associé à des degrés divers de résistance ou de sensibilité à la tremblante ouvre une voie féconde pour comprendre le lien entre les propriétés structurales de la protéine et le mécanisme du développement de la pathologie. Les travaux menés par les équipes de l’INRA, en collaboration avec d’autres équipes nationales, ont apporté des renseignements inattendus sur la stabilité et la convertibilité des variants naturellement rencontrés dans les troupeaux européens. Les mécanismes, au niveau atomique, sous-tendant ces caractéristiques ont pu être explicités par la détermination cristallographique de la structure tri-dimensionnelle de la protéine ovine, apportant en même temps une première information expérimentale sur la structure de la protéine pathologique. Des formes intermédiaires de repliement, sous forme d’oligomères solubles, ont pu être isolées in vitro, et se sont révélées neurotoxiques, ouvrant de nouvelles pistes de recherche vers les déterminants respectifs de la mort neuronale et de la réplication du prion.
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- 2004
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16. Ecouter et dire en médecine, une approche psycho-sociale : utiliser la simulation pour former les futurs médecins à la relation thérapeutique
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Ralph Balez, Antonia Blanié, and Alexandre Eghiaian
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relation médicale ,apprentissage de la relation en médecine ,simulation relationnelle médicale ,reformulation en médecine ,Life and Earth Sciences ,analogue modelling ,time/space ,scientist/student ,psychologie sociale - Abstract
Les « simulations relationnelles » sont assurées par un docteur en psychologie sociale et un médecin ; menées dans un cabinet de médecine générale spécialement recréé pour les étudiants médecins. Les séquences avec patients simulés sont regardées en direct, débriefées et ré visionnées. La formation est réalisée sur quatre promotions de 180 futurs médecins répartis en groupes (9 à 14 étudiants) de 4e ou 5e année. L’objectif est de produire une analyse réflexive et rétrospective sur l’activité du médecin généraliste tout en protégeant les apprenants. La formation exposée ici est réalisée pour quatre promotions de 180 futurs médecins répartis en groupes (9 à 14 étudiants) de 4ème ou 5ème année. L’objectif est, tout en protégeant les apprenants, de susciter une analyse réflexive et rétrospective de l’activité du médecin (avec la production d’une synthèse collective écrite sur les situations abordées). In Switzerland, men predominate in higher education science courses. However, biology courses are attended primarily by women. The little success of affirmative actions targeting girls and women in science invites us to re-examine the way these subjects are taught in Geneva primary school. We will show that only biology seems to occupy a proper place in the real curriculum. Put science back in the general knowledge could be a way to attract women in science.
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- 2018
17. Comparison of Proaqt/Pulsioflex
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Grégoire, Weil, Cyrus, Motamed, Alexandre, Eghiaian, Xavier, Monnet, and Stéphanie, Suria
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Adult ,Male ,Hemodynamic Monitoring ,Hemodynamics ,Reproducibility of Results ,Blood Pressure ,Stroke Volume ,Middle Aged ,Esophagus ,Monitoring, Intraoperative ,Abdomen ,Calibration ,Fluid Therapy ,Humans ,Female ,Prospective Studies ,Cardiac Output ,Aged - Abstract
To compare cardiac index (CI) between Proaqt/PulsioFlexIn a single hospital, 49 intermediate-risk oncologic abdominal surgery patients were included in an observational study. We measured the cardiac Index (CI) provided by OD and by the Proaqt/PulsioFlexThe percentages of error before calibration were 51, 58, 82, 81% for 30, 60, 90 and 120min, they were 39, 57, 65, and 54% after calibration. Trending ability is assumed by a 93% concordance rate after applying a 15% exclusion zone. The trend interchangeability rate was 13.75%. The area under the curve for fluid responsiveness measured by PPV and SVV PulsioFlex were respectively 0.67 [0.57-0.77], P0.01 and 0.75 [0.47-0.66], which was not clinically relevant.The Proaqt/Pulsioflex
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- 2018
18. Structural, Mechanical, and Dynamical Variability of the Actin Cortex in Living Cells
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Annafrancesca Rigato, Frederic Eghiaian, and Simon Scheuring
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Chemistry ,Atomic force microscopy ,Biophysics ,macromolecular substances ,Lateral resolution ,Fibroblasts ,Microscopy, Atomic Force ,Actin cytoskeleton ,Time-Lapse Imaging ,Actins ,Cell biology ,Actin Cytoskeleton ,Mice ,Actin remodeling of neurons ,medicine.anatomical_structure ,Cell Biophysics ,Elastic Modulus ,Cortex (anatomy) ,Cell cortex ,NIH 3T3 Cells ,medicine ,Animals ,Actin - Abstract
In eukaryotic cells, an actin-based cortex lines the inner leaflet of the plasma membrane, endowing the cells with crucial mechanical and functional properties. Unfortunately, it has not been possible to study the structural dynamics of the actin cortex at high lateral resolution in living cells. Here, we performed atomic force microscopy time-lapse imaging and mechanical mapping of actin in the cortex of living cells at high lateral and temporal resolution. Cortical actin filaments adopted discernible arrangements, ranging from large parallel bundles with low connectivity to a tight meshwork of short filaments. Mixing of these architectures resulted in attuned cortex networks with specific connectivity, mechanical responses, and marked differences in their dynamic behavior.
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- 2015
19. pH-Controlled Two-Step Uncoating of Influenza Virus
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Frederic Eghiaian, Andreas Herrmann, Salvatore Chiantia, Kai Ludwig, Christian Sieben, Sai Li, Iwan A. T. Schaap, and Chris T. Höfer
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Endosome ,Protein Conformation ,Biophysics ,Hemagglutinin Glycoproteins, Influenza Virus ,Endosomes ,Genome, Viral ,Biology ,medicine.disease_cause ,Endocytosis ,Microscopy, Atomic Force ,Virus ,Madin Darby Canine Kidney Cells ,Viral Matrix Proteins ,Viral Proteins ,Protein structure ,Dogs ,Virus Uncoating ,Influenza A virus ,medicine ,Animals ,Ribonucleoprotein ,Mechanical Phenomena ,Viral matrix protein ,Influenza A Virus, H3N2 Subtype ,Cryoelectron Microscopy ,Virion ,Hydrogen-Ion Concentration ,Virology ,Cell biology ,Ribonucleoproteins ,Cell Biophysics ,Liposomes - Abstract
Upon endocytosis in its cellular host, influenza A virus transits via early to late endosomes. To efficiently release its genome, the composite viral shell must undergo significant structural rearrangement, but the exact sequence of events leading to viral uncoating remains largely speculative. In addition, no change in viral structure has ever been identified at the level of early endosomes, raising a question about their role. We performed AFM indentation on single viruses in conjunction with cellular assays under conditions that mimicked gradual acidification from early to late endosomes. We found that the release of the influenza genome requires sequential exposure to the pH of both early and late endosomes, with each step corresponding to changes in the virus mechanical response. Step 1 (pH 7.5–6) involves a modification of both hemagglutinin and the viral lumen and is reversible, whereas Step 2 (pH
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- 2014
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20. Ecouter et dire en médecine, une approche psycho-sociale : utiliser la simulation pour former les futurs médecins à la relation thérapeutique
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Balez, Ralph, primary, Blanié, Antonia, additional, and Eghiaian, Alexandre, additional
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- 2017
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21. A Hemodynamic Monitor as a Simulation Tool, a Novel Use of the PiCCO2: Technical Description of the Method and Its Application
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Stéphanie Suria, Alexandre Eghiaian, Pascal Blondel, Antony Lanceleur, Arnaud Pouilly, Pierre Meudal de Kerlidy, Anne Laure Le Maho, and Charles Cerf
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business.product_category ,Epidemiology ,Active learning (machine learning) ,Computer science ,Thermodilution ,Medicine (miscellaneous) ,Manikins ,Education ,03 medical and health sciences ,0302 clinical medicine ,Software ,Mode (computer interface) ,Interactivity ,030202 anesthesiology ,SAFER ,Humans ,Set (psychology) ,Simulation Training ,Simulation ,Monitoring, Physiologic ,business.industry ,Hemodynamics ,Internship and Residency ,030208 emergency & critical care medicine ,Transformation (function) ,Modeling and Simulation ,Laptop ,Clinical Competence ,business - Abstract
INTRODUCTION The PiCCO2 is a commonly used monitor, which education remains theoretical and demonstration based. Simulation allows active learning, which may help achieve a better understanding and handling of this device, hence a safer and more effective use. Because of the lack of availability of dedicated simulators and the uselessness of the demonstration mode of monitors for simulation purpose, simulation remains seldom used. We will describe a novel use of the PiCCO2 for simulation training and its experiment in high-fidelity simulation (HFS). METHODS A standard PiCCO2 was modified with software allowing its transformation into a simulator. The values displayed on the screen were managed in real time by an operator using a standard laptop linked to the monitor and using a standard disposable catheter set to execute simulated transpulmonary thermodilution. Nineteen volunteers were requested to assess the realism of the device during scenarios in which the PiCCO2S (simulator) was used in an HFS environment, with a mannequin reproducing a septic shock condition. RESULTS Two experimental sessions were made. PiCCO2S was used in the contextualized setting of HFS, which allowed a good interactivity between the device and its users. Participants had a positive perception of the realism as well as the method's adequacy to achieve a better understanding of the PiCCO2. CONCLUSIONS The PiCCO2S could be obtained from a serial device. Its integration in HFS provided a realistic handling of the device. A built-in simulation mode into serial medical devices may give users an easy access to training.
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- 2016
22. Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(lysine)- g -(PEO) and Poly(lysine)- g -(ligand-modified poly- N -isopropylacrylamide)
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Christophe Tribet, Emmanuelle Marie, Fabrice Dalier, Simon Scheuring, Frederic Eghiaian, Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640) (PASTEUR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Département de Chimie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), HAL-UPMC, Gestionnaire, École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL)
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[CHIM.POLY] Chemical Sciences/Polymers ,Polymers and Plastics ,Polymers ,Surface Properties ,Acrylic Resins ,Bioengineering ,02 engineering and technology ,Ligands ,010402 general chemistry ,01 natural sciences ,Lower critical solution temperature ,Polyethylene Glycols ,Biomaterials ,chemistry.chemical_compound ,Adsorption ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Polylysine ,chemistry.chemical_classification ,Ethylene oxide ,biology ,Ligand ,Temperature ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,[CHIM.POLY]Chemical Sciences/Polymers ,chemistry ,biology.protein ,Poly(N-isopropylacrylamide) ,0210 nano-technology ,Avidin - Abstract
International audience; Adlayers of poly(lysine)-g-PEG comblike copolymer are extensively used to prepare cell-repellant and protein-repellent surfaces by a straightforward coulomb-driven adsorption that is compatible with diverse substrates (glass, Petri dish, etc.). To endow surfaces with functional properties, namely, controlled ligand-protein binding, comblike poly(lysine) derivatives were used to deposit temperature-responsive poly(NIPAM) macrografts mixed with PEG ones on glass surfaces. Simple surface immersion in mixed solutions of biotin-modified poly(lysine)-g-poly(N-isopropylacrylamide) and poly(lysine)-g-poly(ethylene oxide) yielded robust adlayers whose composition reflected the ratio between the two polymers in solution. We show by fluorescence imaging, and comparison with repellent 100% PEGylated patterns, that specific binding of model avidin/particle conjugates (diameters of ca. 10 or 200 nm) was controlled by temperature switch. The biotin ligand was displayed and accessible at low T, or hidden at T > LCST. Topography and mechanical mapping measurements by AFM confirmed the swelling/collapse status of PNIPAM macrografts in the adlayer at low/high T, respectively. Temperature-responsive comblike PLL derivative that can spontaneously cover anionic interfaces is a promising platform enabling good control on the deposition and accessibility of biofunctional groups on various solid surfaces.
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- 2016
23. Effect of Envelope Proteins on the Mechanical Properties of Influenza Virus
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Amedee des Georges, Iwan A. T. Schaap, Claudia Veigel, and Frederic Eghiaian
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Light ,viruses ,Lipid Bilayers ,Biophysics ,Hemagglutinin (influenza) ,Electrons ,Microscopy, Atomic Force ,Biochemistry ,Capsid ,Viral Envelope Proteins ,Viral envelope ,Scattering, Radiation ,Particle Size ,Lipid bilayer ,Molecular Biology ,Micelles ,Liposome ,biology ,Chemistry ,Bilayer ,Cryoelectron Microscopy ,virus diseases ,Cell Biology ,Hydrogen-Ion Concentration ,Orthomyxoviridae ,Lipids ,Kinetics ,Crystallography ,Membrane protein ,Liposomes ,biology.protein ,lipids (amino acids, peptides, and proteins) ,Stress, Mechanical ,Neuraminidase ,Membrane biophysics ,Molecular Biophysics - Abstract
The envelope of the influenza virus undergoes extensive structural change during the viral life cycle. However, it is unknown how lipid and protein components of the viral envelope contribute to its mechanical properties. Using atomic force microscopy, here we show that the lipid envelope of spherical influenza virions is ∼10 times softer (∼0.05 nanonewton nm(-1)) than a viral protein-capsid coat and sustains deformations of one-third of the virion's diameter. Compared with phosphatidylcholine liposomes, it is twice as stiff, due to membrane-attached protein components. We found that virus indentation resulted in a biphasic force-indentation response. We propose that the first phase, including a stepwise reduction in stiffness at ∼10-nm indentation and ∼100 piconewtons of force, is due to mobilization of membrane proteins by the indenting atomic force microscope tip, consistent with the glycoprotein ectodomains protruding ∼13 nm from the bilayer surface. This phase was obliterated for bromelain-treated virions with the ectodomains removed. Following pH 5 treatment, virions were as soft as pure liposomes, consistent with reinforcing proteins detaching from the lipid bilayer. We propose that the soft, pH-dependent mechanical properties of the envelope are critical for the pH-regulated life cycle and support the persistence of the virus inside and outside the host.
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- 2012
24. Management and outcome of head and neck squamous cell carcinomas in obese patients
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Stéphane Temam, S. Deneuve, Hiang Khoon Tan, and A. Eghiaian
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Adult ,Male ,Cancer Research ,medicine.medical_specialty ,Alcohol Drinking ,Population ,Kaplan-Meier Estimate ,Gastroenterology ,Risk Factors ,Median follow-up ,Cervical lymphadenopathy ,Internal medicine ,medicine ,Humans ,Neoplasms, Squamous Cell ,Obesity ,education ,Aged ,Retrospective Studies ,education.field_of_study ,Squamous Cell Carcinoma of Head and Neck ,business.industry ,Carcinoma ,Smoking ,Head and neck cancer ,Cancer ,Middle Aged ,Prognosis ,medicine.disease ,Comorbidity ,Head and neck squamous-cell carcinoma ,Surgery ,Treatment Outcome ,Oncology ,Epidermoid carcinoma ,Head and Neck Neoplasms ,Carcinoma, Squamous Cell ,Female ,Oral Surgery ,medicine.symptom ,business - Abstract
Summary Head and neck squamous cell carcinomas are common lesions, related to chronic smoking and drinking behaviors. But in contrast to other cancers, effect of obesity on occurrence, diagnosis, treatment and prognosis of these tumors remains to date unknown. This is a retrospective review of 111 obese patients (sex ratio = 6.4, median age = 54.5 year old), treated between 1999 and 2007. Risk factors, tumoral localization and staging (41% stage I–II) were the same as in general population. However, we found 26.1% difficult pan-endoscopies, 54% ACE-27 comorbidity scores ⩾2 and 22.5% misstaged cervical lymphadenopathy. Treatment was based upon surgery (61%) or radiotherapy–chemotherapy (39%), and 37% of patients developed complications. Median follow up (38 months) and five-year overall survival (50%) are comparable to data in non obese patients. Although no direct relation between obesity and squamous cell carcinomas of the head and neck was found, obesity causes problems in tumor assessment and increases surgical complications rate. However, final good therapeutic tolerance and overall survival rate show that these patients should be managed like normal weighted ones. Receiving optimal treatments allow them to anticipate equivalent outcome as in general population.
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- 2011
25. Structural Dynamics of Endocytosis by High-Speed Atomic Force Microscopy
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Tagiltsev, Grigory, primary, Eghiaian, Frederic, additional, and Scheuring, Simon, additional
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- 2017
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26. Diversity in prion protein oligomerization pathways results from domain expansion as revealed by hydrogen/deuterium exchange and disulfide linkage
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Thorsten Daubenfeld, Anne-Pascale Bouin, Human Rezaei, Jeanne Grosclaude, Yann Quenet, Guillaume van der Rest, Frederic Eghiaian, Marieke Van Audenhaege, Unité de recherche Virologie et Immunologie Moléculaires (VIM (UR 0892)), Institut National de la Recherche Agronomique (INRA), Laboratoire des mécanismes réactionnels (DCMR), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Salas, Danielle, Unité de recherche Virologie et Immunologie Moléculaires (VIM), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
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Models, Molecular ,STRAIN ,Conformational change ,Hot Temperature ,MESH: Protein Structure, Quaternary ,Amyloid ,Prions ,Disulfide Linkage ,Kinetics ,MESH: Sheep ,MESH: Heat ,[SDV.CAN]Life Sciences [q-bio]/Cancer ,MESH: Microscopy, Electron ,Oligomer ,MESH: Protein Structure, Tertiary ,03 medical and health sciences ,chemistry.chemical_compound ,MESH: Prions ,0302 clinical medicine ,[SDV.CAN] Life Sciences [q-bio]/Cancer ,OLIGOMERS ,Animals ,MESH: Animals ,MESH: Disulfides ,Disulfides ,FOLDING ,KINETICS ,Protein Structure, Quaternary ,Deuterium Exchange Measurement ,Heat ,Microscopy ,Electron ,Models ,Molecular ,Protein Structure ,Quaternary ,Tertiary ,Sheep ,Cancer ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,MESH: Kinetics ,Biological Sciences ,Protein Structure, Tertiary ,Microscopy, Electron ,Crystallography ,Monomer ,MESH: Deuterium Exchange Measurement ,chemistry ,Biophysics ,Hydrogen–deuterium exchange ,MESH: Models, Molecular ,030217 neurology & neurosurgery - Abstract
The prion protein (PrP) propensity to adopt different structures is a clue to its biological role. PrP oligomers have been previously reported to bear prion infectivity or toxicity and were also found along the pathway of in vitro amyloid formation. In the present report, kinetic and structural analysis of ovine PrP (OvPrP) oligomerization showed that three distinct oligomeric species were formed in parallel, independent kinetic pathways. Only the largest oligomer gave rise to fibrillar structures at high concentration. The refolding of OvPrP into these different oligomers was investigated by analysis of hydrogen/deuterium exchange and introduction of disulfide bonds. These experiments revealed that, before oligomerization, separation of contacts in the globular part (residues 127–234) occurred between the S1–H1–S2 domain (residues 132–167) and the H2–H3 bundle (residues 174–230), implying a conformational change of the S2–H2 loop (residues 168–173). The type of oligomer to be formed depended on the site where the expansion of the OvPrP monomer was initiated. Our data bring a detailed insight into the earlier conformational changes during PrP oligomerization and account for the diversity of oligomeric entities. The kinetic and structural mechanisms proposed here might constitute a physicochemical basis of prion strain genesis.
- Published
- 2007
27. Lipid Chirality Revisited: A Change in Lipid Configuration Transforms Membrane-Bound Protein Domains
- Author
-
Frederic Eghiaian
- Subjects
biology ,Stereochemistry ,Chemistry ,Biophysical Letter ,New and Notable ,Vesicle ,Protein subunit ,Trihexosylceramides ,Protein domain ,Cell Membrane ,Fatty Acids ,Biophysics ,Biological membrane ,Shiga toxin ,Shiga Toxin 2 ,Membrane ,biology.protein ,Enantiomer ,Chirality (chemistry) ,Hydroxy Acids ,Unilamellar Liposomes ,Protein Binding - Abstract
Since its discovery by Louis Pasteur in 1848 (1), chirality has been—and still is to this day—one major topic for chemists and biochemists alike. Many chirality-related phenomena, from alteration of polarized light to enantioselectivity of enzymes for their substrate, form an integral part of today's university courses in chemical and biological sciences. Similar to the enzymes in charge of their synthesis, phospholipids, glycolipids, and sterols found in biological membranes are chiral. However, even though the effect of chirality on the organization of lipid membranes has been studied (see for example, Weis and McConnell (2)), little is known about the impact of lipid configuration on biological function. In this issue of the Biophysical Journal, Schutte et al. (7) resort to cutting-edge chemical synthesis to generate the unnatural enantiomer of Globotriaosylceramide 3 (Gb3, a glycolipid of established biological importance), and investigate the consequences of changing Gb3 configuration on membrane binding and deformation by Shiga toxin, for which Gb3 is the biological receptor. The Shiga toxin of the bacteria Shigella dysenteriae is a protein that binds Gb3 on the plasma membrane via its B subunit (STxB), and forms membrane-bound protein domains. Importantly, by doing so Shiga toxin induces its own internalization in cells by causing inward curvatures of membranes. This phenomenon is reproduced in vitro by adding STxB to giant unilamellar vesicles (GUVs) containing a small fraction of Gb3, in conditions favoring low membrane tension (3). Like in cells, Gb3 used in in vitro assays is the Gb3-R enantiomer. By replacing Gb3-R with its unnatural enantiomer Gb3-S, Schutte et al. (7) observe that STxB-induced tubulation of GUVs is significantly enhanced, based on experiments with a total of 1253 GUVs. Although the affinity of STxB was the same for Gb3-S as for its natural counterpart, reflectometric interference spectroscopy suggested that the domain height and protein distribution in Gb3-S membranes significantly differed from that in Gb3-R membranes. Those observations were confirmed by atomic force microscopy (AFM) imaging of STxB domains formed in mica-supported planar bila-yers composed of DOPC, DPPC, and Gb3. Taken together, those observation show that, in the words of the authors, .Gb3-R favorably induces large
- Published
- 2015
28. New and Notable Lipid Chirality Revisited: A Change in Lipid Configuration Transforms Membrane-Bound Protein Domains
- Author
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Eghiaian, Frederic, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Aix-Marseille Université, Laboratoire U1006
- Subjects
[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology - Abstract
Commentaire d'article; International audience; Since its discovery by Louis Pasteur in 1848 (1), chirality has been—and still is to this day—one major topic for chemists and biochemists alike. Many chirality-related phenomena, from alteration of polarized light to enantioselectivity of enzymes for their substrate, form an integral part of today's university courses in chemical and biological sciences. Similar to the enzymes in charge of their synthesis, phospholipids, glycolipids, and sterols found in biological membranes are chiral. However, even though the effect of chirality on the organization of lipid membranes has been studied (see for example, Weis and McConnell (2)), little is known about the impact of lipid configuration on biological function. In this issue of the Biophysical Journal, Schütte et al. (7) resort to cutting-edge chemical synthesis to generate the unnatural enantiomer of Globotriaosylceramide 3 (Gb3, a glycolipid of established biological importance), and investigate the consequences of changing Gb3 configuration on membrane binding and deformation by Shiga toxin, for which Gb3 is the biological receptor. The Shiga toxin of the bacteria Shigella dysenteriae is a protein that binds Gb3 on the plasma membrane via its B subunit (STxB), and forms membrane-bound protein domains. Importantly, by doing so Shiga toxin induces its own internalization in cells by causing inward curvatures of membranes. This phenomenon is reproduced in vitro by adding STxB to giant unilamellar vesicles (GUVs) containing a small fraction of Gb3, in conditions favoring low membrane tension (3). Like in cells, Gb3 used in in vitro assays is the Gb3-R enantiomer. By replacing Gb3-R with its unnatural enantiomer Gb3-S, Schütte et al. (7) observe that STxB-induced tubulation of GUVs is significantly enhanced, based on experiments with a total of 1253 GUVs. Although the affinity of STxB was the same for Gb3-S as for its natural counterpart, reflectometric interference spectroscopy suggested that the domain height and protein distribution in Gb3-S membranes significantly differed from that in Gb3-R membranes. Those observations were confirmed by atomic force microscopy (AFM) imaging of STxB domains formed in mica-supported planar bila-yers composed of DOPC, DPPC, and Gb3. Taken together, those observation show that, in the words of the authors, .Gb3-R favorably induces large
- Published
- 2015
29. Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales
- Author
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Annafrancesca Rigato, Frederic Eghiaian, Felix Rico, Simon Scheuring, Mathieu Piel, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Compartimentation et dynamique cellulaires (CDC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie [Paris]-Centre National de la Recherche Scientifique (CNRS), Aix-Marseille Université, Laboratoire U1006, and Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Université Pierre et Marie Curie - Paris 6 (UPMC)
- Subjects
Materials science ,Cells ,Cell ,General Physics and Astronomy ,Geometry ,02 engineering and technology ,[SDV.BC]Life Sciences [q-bio]/Cellular Biology ,Microscopy, Atomic Force ,Article ,03 medical and health sciences ,Cell Adhesion ,medicine ,[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Humans ,General Materials Science ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Cell adhesion ,Cytoskeleton ,[SDV.BC] Life Sciences [q-bio]/Cellular Biology ,Cells, Cultured ,030304 developmental biology ,0303 health sciences ,biology ,Atomic force microscopy ,General Engineering ,Force spectroscopy ,021001 nanoscience & nanotechnology ,Fibronectin ,Crosstalk (biology) ,Multicellular organism ,medicine.anatomical_structure ,biology.protein ,Biophysics ,Stress, Mechanical ,0210 nano-technology - Abstract
International audience; In multicellular organisms, cell shape and organization are dictated by cell-cell or cell-extracellular matrix adhesion interactions. Adhesion complexes crosstalk with the cytoskeleton enabling cells to sense their mechanical environment. Unfortunately, most of cell biology studies, and cell mechanics studies in particular, are conducted on cultured cells adhering to a hard, homogeneous, and unconstrained substrate with nonspecific adhesion sites, thus far from physiological and reproducible conditions. Here, we grew cells on three different fibronectin patterns with identical overall dimensions but different geometries (▽, T, and Y), and investigated their topography and mechanics by atomic force microscopy (AFM). The obtained mechanical maps were reproducible for cells grown on patterns of the same geometry, revealing pattern-specific subcellular differences. We found that local Young's moduli variations are related to the cell adhesion geometry. Additionally, we detected local changes of cell mechanical properties induced by cytoskeletal drugs. We thus provide a method to quantitatively and systematically investigate cell mechanics and their variations, and present further evidence for a tight relation between cell adhesion and mechanics.
- Published
- 2015
30. Article Structural, Mechanical, and Dynamical Variability of the Actin Cortex in Living Cells: Actin Cortex Dynamics
- Author
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Eghiaian, Frederic, Rigato, Annafrancesca, Scheuring, Simon, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Aix-Marseille Université, Laboratoire U1006, and INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE - - Amidex2011 - ANR-11-IDEX-0001 - IDEX - VALID
- Subjects
Atomic Force Microscopy AFM ,Mechanical Characterization ,macromolecular substances ,[SDV.BC]Life Sciences [q-bio]/Cellular Biology ,[SDV.BC] Life Sciences [q-bio]/Cellular Biology ,Actin - Abstract
International audience; In eukaryotic cells, an actin-based cortex lines the inner leaflet of the plasma membrane, endowing the cells with crucial mechanical and functional properties. Unfortunately, it has not been possible to study the structural dynamics of the actin cortex at high lateral resolution in living cells. Here, we performed atomic force microscopy time-lapse imaging and mechanical mapping of actin in the cortex of living cells at high lateral and temporal resolution. Cortical actin filaments adopted discernible arrangements, ranging from large parallel bundles with low connectivity to a tight meshwork of short filaments. Mixing of these architectures resulted in attuned cortex networks with specific connectivity, mechanical responses, and marked differences in their dynamic behavior.
- Published
- 2015
31. How to rationalize preoperative tests? A method to implement local guidelines successfully
- Author
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Stéphanie Suria, Grégoire Weil, Alexandre Eghiaian, and Hakim Harkouk
- Subjects
Adult ,Male ,medicine.medical_specialty ,Physical examination ,Guidelines as Topic ,Audit ,Critical Care and Intensive Care Medicine ,Preoperative care ,03 medical and health sciences ,0302 clinical medicine ,Clinical Protocols ,030202 anesthesiology ,Preoperative Care ,Medicine ,Humans ,030212 general & internal medicine ,Medical prescription ,Intensive care medicine ,Aged ,Retrospective Studies ,Protocol (science) ,medicine.diagnostic_test ,business.industry ,Preoperative screening ,Retrospective cohort study ,General Medicine ,Middle Aged ,Anesthesiology and Pain Medicine ,Prescriptions ,Emergency medicine ,Observational study ,Female ,France ,business - Abstract
Background Preoperative screening includes clinical examination and tests. Systematic prescription leads to excessive tests. We conducted an observational retrospective study to assess the success of implementing a protocol-guided prescription procedure for preoperative tests (PTs). We compared the number of PTs prescribed for scheduled surgery before and after the implementation of local guidelines with a specific method. Methods Local guidelines for prescribing PTs based on the French Society of Anaesthesia's recommendations were developed, validated by the anaesthesia team and actively implemented. The implementation procedure was complex and based on the application of sociologic concepts to facilitate PT prescriptions in accordance with the protocol. All PTs (except for children and emergency surgeries) prescribed over a one-week observation period were analysed before and after protocol implementation, respectively in 2011 and 2013. Results Two hundred and ninety-two patient files were analysed: 157 in 2011 and 135 in 2013. Ninety-one percent of the prescriptions were in accordance with the recommendations in 2013. Excessive prescribing decreased significantly after the implementation of recommendations (7.1% versus 20.7%, P Conclusion We observed excellent adherence to the prescription protocol for PTs. The method used to implement the protocol was successful. A future evaluation should be undertaken to confirm these results over the long-term.
- Published
- 2015
32. Lien entre type génétique et résistance des ovins à la Tremblante : une approche structurale et physico-chimique
- Author
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Michael C. Marden, Thomas Haertlé, Jeanne Grosclaude, Marcel Knossow, Pascale Debey, Frederic Eghiaian, Human Rezaei, Unité de recherche Virologie et Immunologie Moléculaires (VIM (UR 0892)), Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'étude des interactions des molécules alimentaires, Substitut du sang et pathologie moléculaire du globule rouge, Institut National de la Santé et de la Recherche Médicale (INSERM), and Muséum national d'Histoire naturelle (MNHN)
- Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,Genetics ,Genetic variants ,Scrapie ,Biology ,Prion protein ,Sciences agricoles ,Agricultural sciences - Abstract
Le polymorphisme génétique de la protéine prion ovine associé à des degrés divers de résistance ou de sensibilité à la tremblante ouvre une voie féconde pour comprendre le lien entre les propriétés structurales de la protéine et le mécanisme du développement de la pathologie. Les travaux menés par les équipes de l’INRA, en collaboration avec d’autres équipes nationales, ont apporté des renseignements inattendus sur la stabilité et la convertibilité des variants naturellement rencontrés dans les troupeaux européens. Les mécanismes, au niveau atomique, sous-tendant ces caractéristiques ont pu être explicités par la détermination cristallographique de la structure tri-dimensionnelle de la protéine ovine, apportant en même temps une première information expérimentale sur la structure de la protéine pathologique. Des formes intermédiaires de repliement, sous forme d’oligomères solubles, ont pu être isolées in vitro, et se sont révélées neurotoxiques, ouvrant de nouvelles pistes de recherche vers les déterminants respectifs de la mort neuronale et de la réplication du prion., Ovine prion protein genetic variants are associated with scrapie susceptibility or resistance : they pave the way to understanding the link between protein structural properties and pathogenesis. The studies developed by INRA teams, in association with other national groups, have brought unexpected informations on the stability and conversion of naturally occurring variants in European sheep breeds. The mechanisms underlying these characteristics were unveiled at the atomic level owing to the crystallographic determination of ovine 3D structure, providing the first experimental insight into the structure of the pathological protein. Unfolding intermediates revealed to be small soluble oligomers, which were purified and displayed neurotoxic effects on primary embryonic neurones. Mutational approaches are currently being developed to identify structural determinants of neuronal death on the one hand, and of prion replication on the other hand.
- Published
- 2004
33. Amyloidogenic Unfolding Intermediates Differentiate Sheep Prion Protein Variants
- Author
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Pascale Mentre, Human Rezaei, Thomas Haertlé, Yvan Choiset, Jeanne Grosclaude, Frederic Eghiaian, Pascale Debey, Eric Treguer, Unité de recherche Virologie et Immunologie Moléculaires (VIM (UR 0892)), Institut National de la Recherche Agronomique (INRA), Laboratoire d'étude des interactions des molécules alimentaires, and ProdInra, Migration
- Subjects
Amyloid ,Protein Folding ,Prions ,Scrapie ,Protein Structure, Secondary ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,Protein structure ,Structural Biology ,law ,Genotype ,[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Animals ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Protein Structure, Quaternary ,Molecular Biology ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,2. Zero hunger ,Genetics ,0303 health sciences ,Sheep ,Chemistry ,VARIABILITE ,030302 biochemistry & molecular biology ,Temperature ,Genetic Variation ,Hydrogen-Ion Concentration ,Phenotype ,Kinetics ,AGENT DE LA TREMBLANTE ,Biochemistry ,Recombinant DNA ,Cattle ,Protein folding ,Thioflavin - Abstract
Sheep is a unique example among mammalian species to present a strong correlation between genotype and prion disease susceptibility phenotype. Indeed a well-defined set of PrP polymorphisms at positions 136, 154 and 171 (sheep numbering) govern scrapie susceptibility, ranging from very high susceptibility for V136-R154-Q171 variant (VRQ) to resistance for A136-R154-R171 variant (ARR). To get better insight into the molecular mechanisms of scrapie susceptibility/resistance, the unfolding pathways of the different full-length recombinant sheep prion protein variants were analysed by differential scanning calorimetry in a wide range of pH. In the pH range 4.5-6.0, thermal unfolding occurs through a reversible one-step process while at pH4.5 and6.0 unfolding intermediates are formed, which are stable in the temperature range 65-80 degrees C. While these general behaviours are shared by all variants, VRQ and ARQ (susceptibility variants) show higher thermal stability than AHQ and ARR (resistance variants) and the formation of their unfolding intermediates requires higher activation energy than in the case of AHQ and ARR. Furthermore, secondary structures of the unfolding intermediates differentiate variants: ARR unfolding intermediate exhibits random coil structure, contrasting with the beta-sheet structure of VRQ and ARQ unfolding intermediates. The rate of the unfolding intermediate formation allows us to classify genetic variants along increasing scrapie susceptibility at pH 4.0, VRQ and ARQ rates being the highest. Rather poor correlation is observed at pH 7.2. Upon cooling, these intermediates refold into stable species, which are rich in beta-type secondary structures and, as revealed by thioflavin T fluorescence and electron microscopy, share amyloid characteristics. These results highlight the prion protein plasticity genetically modulated in sheep, and might provide a molecular basis for sheep predisposition to scrapie taking into account both thermodynamic stability and transconformation rate of prion protein.
- Published
- 2002
34. Structural Dynamics of Endocytosis by High-Speed Atomic Force Microscopy
- Author
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Frederic Eghiaian, Grigory Tagiltsev, and Simon Scheuring
- Subjects
Budding ,biology ,Hexagonal crystal system ,Atomic force microscopy ,Chemistry ,Vesicle ,Biophysics ,Endocytosis ,Clathrin ,Cell biology ,Membrane ,biology.protein ,Molecule - Abstract
Clathrin-mediated endocytosis is one of the major endocytosis pathways. Formation of clathrin coated vesicles (CCV) begins from relatively flat plasma membrane regions. Clathrin molecules bind to the CCV budding sites and assemble into a lattice covering growing vesicle. Initial flat clathrin lattice displays a hexagonal honeycomb architecture whereas the final CCV displays a mixture of hexagons and pentagons. The relation between clathrin lattice conversion and curvature generation in that process remains unknown. No dynamic structural analysis of the detailed mechanisms during CCV budding was achieved so far. High-speed atomic force microscopy (HS-AFM) permits observation of structural dynamics in biological processes because it allows performing imaging with nanometer spatial and subsecond temporal resolution. To study the CCV transformation by HS-AFM, we use a cell-free endocytosis assay based on plasma membrane patches. Combination of HS-AFM together with cell-free assay should permit direct, real-time observation of clathrin lattice rearrangement during CCV budding.
- Published
- 2017
35. [Closed loop goal directed fluid therapy: anesthesia still has a lot to learn from aviation]
- Author
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A, Eghiaian, G, Weil, and S, Suria
- Subjects
Automation ,Anesthesiology ,Aerospace Medicine ,Fluid Therapy ,Humans ,Goals ,Perioperative Care - Published
- 2014
36. High-speed atomic force microscopy: Imaging and force spectroscopy
- Author
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Frederic Eghiaian, Felix Rico, Simon Scheuring, Adai Colom, Ignacio Casuso, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), ANR-12-BSV8-0006,AFM-2-BioMed,Assemblage des proteines dans des membranes de tissus sains et pathologiques par Microscopie à Force Atomique(2012), ANR-12-BS10-0009,Opt-Spect-HS-AFM,Intégration de la microscopie optique avec la microscopie à forces atomiques à haute vitesse et développement de la spectroscopie moléculaire de forces à haute vitesse(2012), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), European Project: 310080,MEM-STRUCT-AFM, Aix-Marseille Université, U1006, BLANC - Assemblage des proteines dans des membranes de tissus sains et pathologiques par Microscopie à Force Atomique - - AFM-2-BioMed2012 - ANR-12-BSV8-0006 - BLANC - VALID, BLANC - Intégration de la microscopie optique avec la microscopie à forces atomiques à haute vitesse et développement de la spectroscopie moléculaire de forces à haute vitesse - - Opt-Spect-HS-AFM2012 - ANR-12-BS10-0009 - BLANC - VALID, INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE - - Amidex2011 - ANR-11-IDEX-0001 - IDEX - VALID, and European Research Council Grant (#310080) - MEM-STRUCT-AFM - 310080 - INCOMING
- Subjects
Titin ,Biophysics ,Nanotechnology ,02 engineering and technology ,Microscopy, Atomic Force ,Biochemistry ,03 medical and health sciences ,Scanning probe microscopy ,Actin cortex ,Structural Biology ,[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Genetics ,Fluorescence microscope ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Molecular Biology ,Biological sciences ,Mechanical Phenomena ,030304 developmental biology ,High-speed force spectroscopy ,0303 health sciences ,Chemistry ,Atomic force microscopy ,High-speed atomic force microscopy ,Cell Membrane ,Resolution (electron density) ,technology, industry, and agriculture ,Membrane structure ,Force spectroscopy ,Cell Biology ,021001 nanoscience & nanotechnology ,Molecular machine ,Biomechanical Phenomena ,Molecular Imaging ,Membrane protein ,biological sciences ,0210 nano-technology - Abstract
International audience; Keywords: High-speed atomic force microscopy High-speed force spectroscopy Membrane protein Membrane structure Titin Actin cortex a b s t r a c t Atomic force microscopy (AFM) is the type of scanning probe microscopy that is probably best adapted for imaging biological samples in physiological conditions with submolecular lateral and vertical resolution. In addition, AFM is a method of choice to study the mechanical unfolding of proteins or for cellular force spectroscopy. In spite of 28 years of successful use in biological sciences, AFM is far from enjoying the same popularity as electron and fluorescence microscopy. The advent of high-speed atomic force microscopy (HS-AFM), about 10 years ago, has provided unprecedented insights into the dynamics of membrane proteins and molecular machines from the single-molecule to the cellular level. HS-AFM imaging at nanometer-resolution and sub-second frame rate may open novel research fields depicting dynamic events at the single bio-molecule level. As such, HS-AFM is complementary to other structural and cellular biology techniques, and hopefully will gain acceptance from researchers from various fields. In this review we describe some of the most recent reports of dynamic bio-molecular imaging by HS-AFM, as well as the advent of high-speed force spectroscopy (HS-FS) for single protein unfolding.
- Published
- 2014
37. The use of a clinical database in an anesthesia unit: focus on its limits
- Author
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Marie Laurence Guye, Jean Louis Bourgain, Grégoire Weil, Alexandre Eghiaian, and Cyrus Motamed
- Subjects
Quality Control ,medicine.medical_specialty ,Time Factors ,Databases, Factual ,Nausea ,Vomiting ,Pain ,Health Informatics ,Critical Care and Intensive Care Medicine ,computer.software_genre ,Anesthesia Procedure ,Ondansetron ,Automation ,Anesthesiology ,Medicine ,Humans ,Anesthesia ,Postoperative Period ,Pain Measurement ,Postoperative Care ,Database ,Morphine ,business.industry ,Reproducibility of Results ,Missing data ,Respiration, Artificial ,Anesthesiology and Pain Medicine ,Observational study ,medicine.symptom ,business ,computer ,Quality assurance ,medicine.drug - Abstract
Anesthesia information management system (AIMS) can be used a part of quality assurance program to improve patient care, however erroneous or missing data entries may lead to misinterpretation. This study assesses the accuracy of information extracted for six consecutive years from a database linked to an automatic anesthesia record-keeping system. An observational study was conducted on a database linked AIMS system. The database was filled in real time during surgical/anesthesia procedure and in the post-anesthesia care unit. The following items: name of the anesthetist, duration of anesthesia, duration of monitoring, ventilatory status upon arrival in postoperative care unit, pain scores, nausea and vomiting scores, pain medication (morphine) and anti nausea and vomiting drug consumption (ondansetron) were extracted and analysed in order to determine exhaustivity (percentage of missing data) and accuracy of the database. The analysis covered 55,946 anaesthetic procedures. The rate of missing data was initially high upon installation but decreased over time. It was limited to 5 % after 3 years for items such as start of anesthesia or name of the anesthetist. However exhaustivity/completeness of some other variable, such as nausea and vomiting started as low as 50 % to reach 20 % at 2008. After cross analysing pain and post-operative nausea and vomiting scores with related medication consumption, (morphine and ondansetron) we conclude that missing data was due to omission of a zero score rather than human error. The follow-up of quality assurance program may use data from AIMS provided that missing or erroneous values be mentioned and their impact on calculations accurately analysed.
- Published
- 2014
38. [About laryngeal mask: is the lowest price material the better cost-efficacy choice?]
- Author
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G, Weil, J, Matysiak, M-L, Guye, A, Eghiaian, and J-L, Bourgain
- Subjects
Adult ,Male ,Postoperative Complications ,Cost-Benefit Analysis ,Humans ,Female ,Prospective Studies ,Middle Aged ,Anesthesia, Inhalation ,Disposable Equipment ,Intraoperative Complications ,Laryngeal Masks ,Aged - Abstract
The main goal of this study was to achieve a medico-economic comparison between four disposable laryngeal masks (LM) (LMA-Unique™, Ambu AuraOnce™, I-Gel™ and LMA-Suprême™).A prospective, randomized, monocentre study.In a center, using routinely LMA-Unique masks, scheduled breast surgery patients were allocated into four groups according to the LM model. After the induction, the modalities of use were collected, as well as the intraoperative events that required additional anesthetic equipment. The real cost of each model was calculated (cost of the mask+extra cost related to complications). Using the LMA-Unique as a reference, we performed a cost-efficacy analysis. We realized a cost-efficiency analysis putting in parallel the impact on the cost and the incidence of the events.A total of 178 patients were included. According to the cost-efficacy analysis, the dominant model was the Ambu AuraOnce™ (Δreal cost: -34.2%, Δevents: -30.6%). The LMA-Unique™ was dominated because of a high morbidity rate. The I-Gel™ and LMA-Suprême™ models were more efficient but more expensive (Δreal cost: +16% and +22.5% respectively). To compensate for additional costs, it would be necessary to apply a price reduction of at least 50%.Despite their better efficiency and safety, the latest generation laryngeal masks are still expensive in spite of a low rate of complication. These results do not take into account very rare and severe complications not met in this study in the limited size; then the economic and medical impact can influence the choice beyond the simple analysis cost-efficiency.
- Published
- 2014
39. Lipid Chirality Revisited: A Change in Lipid Configuration Transforms Membrane-Bound Protein Domains
- Author
-
Eghiaian, Frederic, Aix-Marseille Université, U1006, BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory (Bio-AFM-Lab), and Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Quantitative Biology::Subcellular Processes ,[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Condensed Matter::Strongly Correlated Electrons - Abstract
new applications of AFM
- Published
- 2014
40. Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(lysine)-g-(PEO) and Poly(lysine)-g-(ligand-modified poly-N-isopropylacrylamide)
- Author
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Dalier, F., primary, Eghiaian, F., additional, Scheuring, S., additional, Marie, E., additional, and Tribet, C., additional
- Published
- 2016
- Full Text
- View/download PDF
41. A Hemodynamic Monitor as a Simulation Tool, a Novel Use of the PiCCO2
- Author
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Eghiaian, Alexandre, primary, Lanceleur, Antony, additional, Le Maho, Anne Laure, additional, Pouilly, Arnaud, additional, de Kerlidy, Pierre Meudal, additional, Blondel, Pascal, additional, Suria, Stéphanie, additional, and Cerf, Charles, additional
- Published
- 2016
- Full Text
- View/download PDF
42. Simulation de situations critiques en chirurgie robotique : résultats préliminaires d’une méthode économique, interprofessionnelle et mobile
- Author
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Charles Honoré, Stéphanie Suria, Alexandre Eghiaian, Philippe Morice, Aurelia Barraud, Léonor Benhaim, and Pascal Baguenard
- Subjects
Anesthesiology and Pain Medicine - Abstract
Introduction La chirurgie robotique est en plein essor. La gestion des urgences vitales (medicales et laparoconversions) est compliquee par les contraintes ergonomiques specifiques du robot ce qui est prejudiciable pour la securite des patients [1] . La simulation permet aux equipes d’etudier ces contraintes, de les anticiper et d’adapter les protocoles. Nous presentons les premiers resultats d’une methode de simulation peu couteuse et adaptable. Materiel et methodes Six heures de simulation dans la salle d’operation dediee a cette chirurgie ont ete organisees avec les referents en chirurgie robotique de Gustave-Roussy. Un mannequin basse-fidelite Gaumard® hybride avec un simulateur procedural de type « pelvi trainer » permettant l’usage reel du robot et un simulateur de parametres vitaux Prosim 8 (Fluke Medical®) ont ete utilises. Le robot Da Vinci Xi© d’Intuitive Surgical® a ete deploye dans les conditions ergonomiques et materielles reproduisant celles d’un patient opere d’une chirurgie robotique pelvienne. Trois scenarios ont ete etudies : laparoconversion en urgence vitale pour hemorragie (LCV), arret cardiorespiratoire peroperatoire (ACR), et retrait d’une pince bloquee (RPB). Une check list de retrait des bras du robot en urgence vitale entierement inedite a ete etudiee lors de ces scenarios. Resultats Des elements specifiques non encore envisages ont ete identifies et des mesures correctrices ont ete immediatement appliquees : – en cas de LCV : necessite d’un ecarteur abdominal disponible systematiquement dans en salle d’operation, modification de la position des bras du robot pour le retrait en urgence, necessite de former les internes de chirurgie au retrait urgent du robot ; – en cas d’ACR : difficulte de poses d’electrodes de defibrillateur ; l’absence de coordination entre le retrait du robot et le debut de la reanimation a entraine un temps de no flow de 70 s. La mise en place de mesures correctrices a permis de reduire ce temps a 20 s lors d’un 2e scenario ; – en cas de RPB : localisation de l’ouitl specifique diffusee et validee. Manipulation de celui-ci repetee en situation non urgente par les chirurgiens et les IBODE. Par extension la situation de deblocage en cas de panne electrique a ete abordee. Le contenu de la check list a ensuite ete modifie et valide en consequence ( Fig. 1 ). Discussion Une simulation in situ hybride low cost, sans mannequin haute-fidelite, mais rapide a mettre en œuvre, a permis de reproduire les conditions de la chirurgie pelvienne robotique avec realisme. Cela a rendu possible l’etude d’une check list specifique et de son utilisation, ainsi que l’analyse precise des contraintes et des obstacles a la gestion des urgences restees latentes jusque-la. Ce type de simulation interprofessionnelle permettrait de mieux apprehender les situations critiques avant de demarrer l’activite de chirurgie robotique, et de former les divers acteurs, efficacement et a faible cout. La methode sera renouvelee en chirurgie ORL avec les memes objectifs et pourrait confirmer son efficacite. Une check list specifique sera aussi developpee.
- Published
- 2015
43. Structural and dynamic characterization of biochemical processes by atomic force microscopy
- Author
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Frédéric, Eghiaian and Iwan A T, Schaap
- Subjects
Proteins ,Microscopy, Atomic Force - Abstract
Atomic Force Microscopy (AFM) has gained increasing popularity over the years among biophysicists due to its ability to image and to measure pN to nN forces on biologically relevant scales (nm to μm). Continuous technical developments have made AFM capable of nondisruptive, subsecond imaging of fragile biological samples in a liquid environment, making this method a potent alternative to light microscopy. In this chapter, we discuss the basics of AFM, its theoretical limitations, and we describe how this technique can be used to get single protein resolution in liquids at room temperature. Provided imaging is done at low-enough forces to avoid sample disruption and conformational changes, AFM allows obtaining unique insights into enzyme dynamics.
- Published
- 2011
44. Structural and Dynamic Characterization of Biochemical Processes by Atomic Force Microscopy
- Author
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Frederic Eghiaian and Iwan A. T. Schaap
- Subjects
0303 health sciences ,03 medical and health sciences ,Materials science ,Atomic force microscopy ,Microscopy ,Resolution (electron density) ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,030304 developmental biology ,Characterization (materials science) - Abstract
Atomic Force Microscopy (AFM) has gained increasing popularity over the years among biophysicists due to its ability to image and to measure pN to nN forces on biologically relevant scales (nm to μm). Continuous technical developments have made AFM capable of nondisruptive, subsecond imaging of fragile biological samples in a liquid environment, making this method a potent alternative to light microscopy. In this chapter, we discuss the basics of AFM, its theoretical limitations, and we describe how this technique can be used to get single protein resolution in liquids at room temperature. Provided imaging is done at low-enough forces to avoid sample disruption and conformational changes, AFM allows obtaining unique insights into enzyme dynamics.
- Published
- 2011
45. Système de boucle fermée pour l’optimisation hémodynamique peropératoire : l’anesthésie a encore à apprendre de l’aéronautique
- Author
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Stéphanie Suria, Grégoire Weil, and Alexandre Eghiaian
- Subjects
Anesthesiology and Pain Medicine ,business.industry ,Medicine ,General Medicine ,business - Published
- 2014
46. Simulation de situations critiques en chirurgie robotique : résultats préliminaires d’une méthode économique, interprofessionnelle et mobile
- Author
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Eghiaian, Alexandre, primary, Suria, Stéphanie, additional, Barraud, Aurelia, additional, Baguenard, Pascal, additional, Honoré, Charles, additional, Benhaïm, Léonor, additional, and Morice, Philippe, additional
- Published
- 2015
- Full Text
- View/download PDF
47. Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales
- Author
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Rigato, Annafrancesca, primary, Rico, Felix, additional, Eghiaian, Frédéric, additional, Piel, Mathieu, additional, and Scheuring, Simon, additional
- Published
- 2015
- Full Text
- View/download PDF
48. Lipid Chirality Revisited: A Change in Lipid Configuration Transforms Membrane-Bound Protein Domains
- Author
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Eghiaian, Frederic, primary
- Published
- 2015
- Full Text
- View/download PDF
49. Corrigendum to “High-speed atomic force microscopy: Imaging and force spectroscopy” [FEBS Lett. 588 (19) (2014) 3631-3638]
- Author
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Eghiaian, F., primary, Rico, F., additional, Colom, A., additional, Casuso, I., additional, and Scheuring, S., additional
- Published
- 2015
- Full Text
- View/download PDF
50. Structural, Mechanical, and Dynamical Variability of the Actin Cortex in Living Cells
- Author
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Eghiaian, Frédéric, primary, Rigato, Annafrancesca, additional, and Scheuring, Simon, additional
- Published
- 2015
- Full Text
- View/download PDF
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