100 research outputs found
Hippocampal activation for autobiographical memories over the entire lifetime in healthy aged subjects: An fMRI study
Get PDFInternational audienceWe used functional magnetic resonance imaging to determine the cerebral structures required during the recollection of episodic autobiographical memories according to 5 time periods covering the whole lifespan to test the 2 concurring models of memory consolidation, which propose either a temporary (standard model) or a permanent (multiple-trace model) role of the hippocampus in episodic memory retrieval. The experimental paradigm was specially designed to engage subjects (67.17 +/- 5.22 years old) in the retrieval of episodic autobiographical memories, whatever the time period, from personally relevant cues selected by questioning a family member. Moreover, the nature of the memories was checked at debriefing by means of behavioral measures to control the degree of episodicity. Behavioral data showed that recollected memories were characterized by specificity and details whatever their remoteness. Main neuroimaging data (Statistical Parametric Mapping 99) revealed the activation of a network including the left superior frontal gyri, bilateral precuneus/posterior cingulate and lingual gyri, left angular gyrus, and left hippocampus, although the subtraction analyses detected subtle differences between certain time periods. Small volume correction centered on the hippocampus detected left hippocampal activation for all time periods and additional right hippocampal activation for the intermediate periods. Further confirmation was provided by using a 3-way analysis of variance on blood oxygen level-dependent values, which revealed hippocampal activation whatever the time interval. The present data challenge the standard model of memory consolidation and support the multiple-trace model, instead. The comparison with previous literature stresses the idea that a bilateral involvement of the hippocampus characterizes rich episodic autobiographical memory recollection
Computationally optimized SARS-CoV-2 MHC class I and II vaccine formulations predicted to target human haplotype distributions
No full textThis dataset contains haplotype frequency measurements for three populations self-reporting as having White, Black, or Asian ancestry. For details of this dataset and data collection, please see:
Computationally optimized SARS-CoV-2 MHC class I and II vaccine formulations predicted to target human haplotype distributions
Ge Liu, Brandon Carter, Trenton Bricken, Siddhartha Jain, Mathias Viard, Mary Carrington, David K. Gifford
Cell Systems, 2020
https://doi.org/10.1016/j.cels.2020.06.009
Please cite this paper if you use this data
Extending the weak order on Coxeter groups
Get PDFWe introduce a new family of complete lattices, arising from a digraph together with a valuation on its vertices and generalizing a previous construction of the author. We then apply this to the study of two long-standing conjectures of Dyer, and we provide a description of the Tamari lattice with this theory
Origin of Laurdan Sensitivity to the Vesicle-to-Micelle Transition of Phospholipid-Octylglucoside System: A Time-Resolved Fluorescence Study
No full textAbstractThe fluorescent probe laurdan has been shown to be sensitive to the vesicle-to-micelle transition of phosphatidylcholine/octylglucoside (M. Paternostre, O. Meyer, C. Grabielle-Madelmont, S. Lesieur, and M. Ollivon, 1995, Biophys. J. 69:2476–2488). On the other hand, a study on the photophysics of laurdan in organic solvents has shown that the complex de-excitation pathway of the probe can be described by two successive processes, i.e., an intramolecular charge transfer followed by dielectric relaxation of the solvent if polar. These two excited-state reactions lead to three emitting states, i.e., a locally excited state, a charge transfer state, and a solvent relaxed state (M. Viard, J. Gallay, M. Vincent, B. Robert and M. Paternostre, 1997, Biophys. J. 73:2221–2234). Experiments have been performed using time-resolved fluorescence on the probe inserted in amphiphile aggregates (mixed liposomes, mixed micelles) different in detergent-to-lipid ratios. The results have been compared with those obtained for laurdan inserted in dipalmitoyl phosphatidylcholine liposomes in the gel and in the fluid lamellar phase. Except for laurdan in dipalmitoyl phosphatidylcholine liposomes in the gel lamellar phase, the red part of the emission spectra originates from the de-excitation of the relaxed excited state of laurdan, indicating that indeed the dielectric relaxation process is an important phenomena in the ground-state return pathway of this probe. On the other hand, the maximization entropy method (MEM) analysis of the fluorescence decay recorded in the blue part of the emission spectra indicates that the dielectric relaxation is not the only reaction occurring to the excited state of laurdan. Moreover, the analysis of the fluorescence decays of laurdan inserted in gel lamellar dipalmitoylphosphatidylcholine (DPPC) liposomes indicates excited-state reactions, although dielectric relaxation is impossible. These results are in agreement with the de-excitation pathway determined from laurdan behavior in organic solvent even if, in most of the aggregates studied in this work, the major phenomenon is the dielectric relaxation of the solvent. All along the vesicle-to-micelle transition, we have observed that the lifetime of the relaxed excited state of laurdan continuously decreases probably due to a dynamic quenching process by water molecules. On the other hand, the time constant of the dielectric relaxation process remains almost unchanged in the lamellar part of the transition but abruptly decreases as soon as the first mixed micelle is formed. This decrease is continuous all over the rest of the transition even if it is more pronounced in the mixed liposomes’ and mixed micelles’ coexistence. The increase of the octylglucoside-to-lipid ratio of the mixed micelles via the change of the size and the shape of the aggregates may facilitate the penetration and the mobility of water molecules. Therefore, during the vesicle-to-micelle transition, laurdan probes the evolution of both the amphiphile packing in the aggregates and the increase of the interface polarity. This study finally shows that the detergent-to-lipid ratio of the mixed micelles is an important parameter to control to limit the penetration and the mobility of water within the amphiphile aggregates and that laurdan is a nice tool to monitor this phenomenon
Predicted Cellular Immunity Population Coverage Gaps for SARS-CoV-2 Subunit Vaccines and their Augmentation by Compact Peptide Sets. Liu et al.
No full textThis dataset contains computational models and data for the following papers:
Predicted Cellular Immunity Population Coverage Gaps for SARS-CoV-2 Subunit Vaccines and their Augmentation by Compact Peptide Sets
Ge Liu, Brandon Carter, David K. Gifford
Cell Systems, 2020
https://doi.org/10.1016/j.cels.2020.11.010
Computationally Optimized SARS-CoV-2 MHC Class I and II Vaccine Formulations Predicted to Target Human Haplotype Distributions
Ge Liu, Brandon Carter, Trenton Bricken, Siddhartha Jain, Mathias Viard, Mary Carrington, David K. Gifford
Cell Systems, 2020
https://doi.org/10.1016/j.cels.2020.06.009
Additional source code is available at https://github.com/gifford-lab/optivax. Haplotype frequency data are available at http://dx.doi.org/10.17632/cfxkfy9zp4.1
Please cite the relevant papers if you use these data
Predicted Cellular Immunity Population Coverage Gaps for SARS-CoV-2 Subunit Vaccines and their Augmentation by Compact Peptide Sets. Liu et al.
No full textThis dataset contains computational models and data for the following papers:
Predicted Cellular Immunity Population Coverage Gaps for SARS-CoV-2 Subunit Vaccines and their Augmentation by Compact Peptide Sets
Ge Liu, Brandon Carter, David K. Gifford
Cell Systems, 2020
https://doi.org/10.1016/j.cels.2020.11.010
Computationally Optimized SARS-CoV-2 MHC Class I and II Vaccine Formulations Predicted to Target Human Haplotype Distributions
Ge Liu, Brandon Carter, Trenton Bricken, Siddhartha Jain, Mathias Viard, Mary Carrington, David K. Gifford
Cell Systems, 2020
https://doi.org/10.1016/j.cels.2020.06.009
Additional source code is available at https://github.com/gifford-lab/optivax. Haplotype frequency data are available at http://dx.doi.org/10.17632/cfxkfy9zp4.1
Please cite the relevant papers if you use these data
Extending the weak order on Coxeter groups
Get PDFInternational audienceWe introduce a new family of complete lattices, arising from a digraph together with a valuation on its vertices and generalizing a previous construction of the author. We then apply this to the study of two long-standing conjectures of Dyer, and we provide a description of the Tamari lattice with this theory
Photo-activation of the hydrophobic probe iodonaphthylazide in cells alters membrane protein function leading to cell death
No full textAbstract Background Photo-activation of the hydrophobic membrane probe 1, 5 iodonaphthylazide (INA) by irradiation with UV light (310–380 nm) results in the covalent modification of transmembrane anchors of membrane proteins. This unique selectivity of INA towards the transmembrane anchor has been exploited to specifically label proteins inserted in membranes. Previously, we have demonstrated that photo-activation of INA in enveloped viruses resulted in the inhibition of viral membrane protein-induced membrane fusion and viral entry into cells. In this study we show that photo-activation of INA in various cell lines, including those over-expressing the multi-drug resistance transporters MRP1 or Pgp, leads to cell death. We analyzed mechanisms of cell killing by INA-UV treatment. The effects of INA-UV treatment on signaling via various cell surface receptors, on the activity of the multi-drug resistance transporter MRP1 and on membrane protein lateral mobility were also investigated. Results INA treatment of various cell lines followed by irradiation with UV light (310–380 nm) resulted in loss of cell viability in a dose dependent manner. The mechanism of cell death appeared to be apoptosis as indicated by phosphatidylserine exposure, mitochondrial depolarization and DNA fragmentation. Inhibition by pan-caspase inhibitors and cleavage of caspase specific substrates indicated that at low concentrations of INA apoptosis was caspase dependent. The INA-UV treatment showed similar cell killing efficacy in cells over-expressing MRP1 function as control cells. Efflux of an MRP1 substrate was blocked by INA-UV treatment of the MRP1-overexpressing cells. Although INA-UV treatment resulted in inhibition of calcium mobilization triggered by chemokine receptor signaling, Akt phosphorylation triggered by IGF1 receptor signaling was enhanced. Furthermore, fluorescence recovery after photobleaching experiments indicated that INA-UV treatment resulted in reduced lateral mobility of a seven transmembrane G protein-coupled receptor. Conclusion INA is a photo-activable agent that induces apoptosis in various cancer cell lines. It reacts with membrane proteins to alter the normal physiological function resulting in apoptosis. This activity of INA maybe exploited for use as an anti-cancer agent.</p
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