42 research outputs found
HIV-1-infected cells increase the formation of epidermal LC-T-cell conjugates.
No full text<p>(A) Inner foreskin explants were exposed for 1 h or 4 h to HIV-1-infected PBMCs. Explants were then double stained with anti-langerin and anti-CD3 Abs, and visualized with DAB and HistoGreen peroxidase substrates, respectively. Shown are calculated means±SEM % LC-T-cell conjugates of the total LCs from three independent explants. Cells were counted in a minimum of 10 fields/section for each experiment. *p = 0.0431 4 h vs. 1 h, Student's t-test. (B–D) Representative images of inner foreskin explants exposed to either non-infected (B) or HIV-1-infected (C and D) PBMCs for 4 h, and double stained for langerin (DAB brown in B and C; Alexa488 green in D) and CD3 (Histogreen blue-green in B and C; Cy5 red in D). Single isolated non-conjugated LCs and T-cells are shown in the framed window in (B), while the framed window in (C) shows LC-T-cell conjugate at the epidermal-dermal interface above the basement membrane (black dotted lines). The confocal microscopy image in (D) shows the close contact between one LC and one T-cell, as well as the LC dendrite in proximity to a second T-cell. Scale bars = 20 µm (B, C) and 8 µm (D). (E) Electron micrograph of LC-T-cell conjugate in inner foreskin explant exposed for 4 h to HIV-1-infected PBMCs. The conjugate is positioned within the epidermis at the epidermal-dermal interface above the basement membrane (black dotted line); scale bar = 1 µm. Higher magnification of the top framed window (right side) shows two rod-shaped Birbeck granule in the LC cytoplasm (black arrows); scale bar = 200 nm. Higher magnification of the bottom framed window (right corner) shows an HIV-1 particle of 90 nm with a central dark core characteristic of mature virions associated with LC; scale bar = 50 nm. “(F) Inner foreskin explants were exposed for 4 h to either non-infected PBMCs (top right) or HIV-1-infected PBMCs: alone (bottom left); in the presence of 40 µg/ml control goat IgG Ab (bottom middle); in the presence of 80 µg/ml neutralizing goat Ab to CCL5/RANTES (bottom right). Following infection, epidermal single-cell suspensions were prepared and double stained with APC-conjugated anti-human langerin and PE-conjugated anti-human CD3 mAbs. Cells were first gated on langerin+ cells (R1 gate, top left profile, insert shows staining with matched isotype control). Numbers represent the percentages of cells in R1 that are both high forward scatter and CD3+. Images are representative of two independent experiments.</p
Monitoring the emergence of a knowledge community : a corpus-based approach
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
Mach wave radiation by mixing layers. Part I: analysis of the sound field
No full textIn Part I a wave packet model is used to show that a time-developing mixing layer produces a Mach wave pattern similar to the one produced by a spatial-developing mixing layer. However, this kind of similarity does not exist for the sound emitted by subsonic sound sources. A method to analyse temporal direct numerical simulation (DNS) results for the Mach wave pattern is then developed and demonstrated using numerical results of the wave-packet model. The method is applied to the temporal DNS results of a supersonic mixing layer undergoing transition to turbulence. Two dominant Mach waves are revealed. The first wave originates from about the time of the Λ-vortex structure dominance in the layer. The second wave appears just prior to the final breakdown of the layer to a fine-scale turbulence structure. The second wave shows a higher level of a finite-amplitude wave behaviour and a smaller-scale source structure than the first wave. Directivity plots and frequency spectra are provided and discussed
Positioning of the MBP α<sub>2</sub>-peptide relative to the DMPC membrane bilayer in molecular dynamics simulations.
No full text<p>The N-terminal end of the α<sub>2</sub>-peptide (S72–S107) of myelin basic protein (MBP) is shown in red, and the C-terminal end is shown in blue. The α-helix was positioned relative to the dimyristoylphosphatidylcholine (DMPC) membrane bilayer (shown in cyan), so that the hydrophobic side-chains of F86 and F87 penetrated the bilayer, whereas hydrophilic residues such as H85 were positioned towards the solvent <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068175#pone.0068175-Harauz2" target="_blank">[20]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068175#pone.0068175-Polverini1" target="_blank">[40]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068175#pone.0068175-Bates1" target="_blank">[51]</a>.</p
Structure of phosphorylated α<sub>2</sub>-peptides at the end of MD experiments in water and in DMPC.
No full text<p>The dimyristoylphosphatidylcholine (DMPC) membrane bilayer and water molecules are not shown in order to improve clarity. The images are a representative snapshot of singly-phosphorylated (PhT92, PhT95), and doubly-phosphorylated (PhT92–PhT95) α<sub>2</sub>-peptides (S72–S107) of myelin basic protein (MBP) captured during the last 10 ns of the 160 ns molecular dynamics simulation experiments. Shown are examples of the type of electrostatic interactions between phosphorylated Thr residues and different basic residues within the α<sub>2</sub>-peptide variants.</p
Evolution of secondary structure of MBP α<sub>2</sub>-peptides with temperature-ramping in a DMPC bilayer environment.
No full text<p>The α<sub>2</sub>-peptides (S72–S107) of myelin basic protein (MBP) were simulated in a dimyristoylphosphatidylcholine (DMPC) membrane bilayer system using the simulated annealing protocol in GROMACS 4.5.5 and the Gromos96 ffG53a6 force-field. The peptide secondary structure was represented using the dictionary of protein secondary structure (DSSP) algorithm <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068175#pone.0068175-Kabsch1" target="_blank">[78]</a>. Data collected for the unmodified, singly-phosphorylated (PhT92, PhT95), and doubly-phosphorylated (PhT92–PhT95) α<sub>2</sub>-peptides were compared. In these <i>in silico</i> molecular dynamics experiments, the α<sub>2</sub>-peptides were heated linearly from 37°C to 500°C, over 10 ns. The temperature was held constant at 500°C for a further 5 ns before linearly cooling the peptide back to 37°C, over 10 ns.</p
The number of PPII structures observed within the proline-rich region of the α<sub>2</sub>-peptide of MBP.
No full text<p>The data were obtained through the analysis of molecular dynamics simulations of α<sub>2</sub>-peptides (S72–S107) of myelin basic protein (MBP) in water as well as in a dimyristoylphosphatidylcholine (DMPC) membrane bilayer system. This proline-rich region (T92-S99) is highly dynamic, and rapidly and reversibly transitions between a left-handed poly-proline II (PPII) structure and other conformations. The data that are presented represent the average frequency of observed PPII structures of at least 2 consecutive residues long within the proline-rich region. The error bars represent the average standard error from multiple independent simulations. In addition to the unmodified peptide, different phosphorylation variants were also analyzed: single phosphorylation at positions T92 and T95 (PhT92 and PhT95, respectively) and double phosphorylation (PhT92–PhT95).</p
Change in tilt angle and membrane penetration depth of the α-helical segment in DMPC.
No full text<p>Data were obtained from analysis of molecular dynamics experiments conducted in the presence of a dimyristoylphosphatidylcholine (DMPC) membrane bilayer for unmodified as well as singly- (PhT92, PhT95) and doubly- (PhT92–PhT95) phosphorylated α<sub>2</sub>-peptides of myelin basic protein (MBP). Panel A1 illustrates how the tilt angle Θ of the α-helix (residues P82-I90, represented as a cylinder) within the α<sub>2</sub>-peptide (S72–S107) was measured. Θ was determined as the angle between the axes passing through the geometric center of the helix and the axis that is parallel to the surface of the membrane. When Θ<0, the N-terminal portion of the helix is tilted away from the membrane surface (pointing upwards) whereas the C-terminal region is embedded (pointing downwards), and when Θ>0, the opposite is true. The evolution of the tilt angle was plotted as a function of simulation time over the entire experiment (A2). The change in penetration depth of the central α-helix into the DMPC bilayer for the unmodified α<sub>2</sub>-peptide, as well as the phosphorylated variants was also plotted (B). The penetration depth represents the distance between the center of mass of the α-helix and the surface of the membrane.</p
The starting structures of the MBP α<sub>2</sub>-peptides used in molecular dynamics simulations.
No full text<p>The structures were derived from NMR data <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068175#pone.0068175-Ahmed1" target="_blank">[49]</a> and energy-minimized before MD experiments. The four α<sub>2</sub>-peptides (S72–S107) of myelin basic protein (MBP) used in this molecular dynamics study are: the unmodified α<sub>2</sub>-peptide, as well as the singly-phosphorylated α<sub>2</sub>-peptides at residues T92 and T95 (PhT92 and PhT95 respectively), and the corresponding doubly-phosphorylated α<sub>2</sub>-peptide (PhT92–PhT95). The N- and C-termini are designated by red and blue colors, respectively.</p
