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https://www.readbyqxmd.com/read/28741728/ebi2-contributes-to-the-induction-of-thymic-central-tolerance-in-mice-by-promoting-rapid-motility-of-medullary-thymocytes
#1
Sanghee Ki, Hiran M Thyagarajan, Zicheng Hu, Jessica N Lancaster, Lauren I R Ehrlich
Maturing thymocytes enter the thymic medulla, where they encounter numerous self-antigens presented by antigen presenting cells (APCs). Those thymocytes that are strongly self-reactive undergo either negative selection or diversion into the regulatory T cell lineage. Although the majority of the proteome is expressed in the medulla, many self-antigens are expressed by only a minor fraction of medullary APCs; thus, thymocytes must efficiently enter the medulla and scan APCs to ensure central tolerance. Chemokine receptors promote lymphocyte migration, organization within tissues, and interactions with APCs in lymphoid organs...
July 25, 2017: European Journal of Immunology
https://www.readbyqxmd.com/read/28738592/a-unique-red-emitting-two-photon-fluorescent-probe-with-tumor-specificity-for-imaging-in-living-cells-and-tissues
#2
Xiuqi Kong, Baoli Dong, Nan Zhang, Chao Wang, Xuezhen Song, Weiying Lin
Tumor-specific imaging can provide an attractive approach for the early detection and prognosis of cancer, as well as the precise image-guided tumor-removal surgery. Herein, we describe a unique red-emitting two-photon fluorescent probe (N-BN) for tumor-specific imaging. N-BN utilized Nile Red as the red-emitting two-photon fluorophore and employed biotin as the tumor-specific ligand. In the presence of a variety of biomolecules or in different pH buffers, the fluorescence intensity of N-BN at 655nm showed no noticeable change...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28736661/brain-tumor-delineation-enhanced-by-moxifloxacin-based-two-photon-cars-combined-microscopy
#3
Viet-Hoan Le, Su Woong Yoo, Yeoreum Yoon, Taejun Wang, Bumju Kim, Seunghun Lee, Kyung-Hwa Lee, Ki Hean Kim, Euiheon Chung
Delineating brain tumor margin is critical for maximizing tumor removal while sparing adjacent normal tissue for better clinical outcome. We describe the use of moxifloxacin-based two-photon (TP)/coherent anti-Stokes Raman scattering (CARS) combined microscopy for differentiating normal mouse brain tissue from metastatic brain tumor tissue based on histoarchitectural and biochemical differences. Moxifloxacin, an FDA-approved compound, was used to label cells in the brain, and moxifloxacin-based two-photon microscopy (TPM) revealed tumor lesions with significantly high cellular density and invading edges in a metastatic brain tumor model...
April 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28734477/polarity-sensitive-probes-for-superresolution-stimulated-emission-depletion-microscopy
#4
Erdinc Sezgin, Falk Schneider, Victoria Zilles, Iztok Urbančič, Esther Garcia, Dominic Waithe, Andrey S Klymchenko, Christian Eggeling
The lateral organization of molecules in the cellular plasma membrane plays an important role in cellular signaling. A critical parameter for membrane molecular organization is how the membrane lipids are packed. Polarity-sensitive dyes are powerful tools to characterize such lipid membrane order, employing, for example, confocal and two-photon microscopy. The investigation of potential nanodomains, however, requires the use of superresolution microscopy. Here, we test the performance of the polarity-sensitive membrane dyes Di-4-ANEPPDHQ, Di-4-AN(F)EPPTEA, and NR12S in superresolution stimulated emission depletion microscopy...
July 19, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28733356/steady-state-free-ca2-in-astrocytes-is-decreased-by-experience-and-impacts-arteriole-tone
#5
Eslam M F Mehina, Ciaran Murphy-Royal, Grant R Gordon
Astrocytes can control basal synaptic strength and arteriole tone via their resting Ca2+ activity. However, whether resting astrocyte Ca2+ can adjust to a new steady-state level, with an impact on surrounding brain cells, remains unknown. Using two-photon Ca2+ imaging in male rat acute brain slices of the somatosensory neocortex, we found that theta burst neural activity produced an unexpected long-lasting reduction in astrocyte free Ca2+ in the soma and endfeet. The drop in intracellular Ca2+ was attenuated by antagonists targeting multiple ionotropic and metabotropic glutamate receptors, and intracellular cascades involved Ca2+ stores and nitric oxide...
July 21, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28728024/origins-of-cell-type-specific-olfactory-processing-in-the-drosophila-mushroom-body-circuit
#6
Kengo Inada, Yoshiko Tsuchimoto, Hokto Kazama
How cell-type-specific physiological properties shape neuronal functions in a circuit remains poorly understood. We addressed this issue in the Drosophila mushroom body (MB), a higher olfactory circuit, where neurons belonging to distinct glomeruli in the antennal lobe feed excitation to three types of intrinsic neurons, α/β, α'/β', and γ Kenyon cells (KCs). Two-photon optogenetics and intracellular recording revealed that whereas glomerular inputs add similarly in all KCs, spikes were generated most readily in α'/β' KCs...
July 19, 2017: Neuron
https://www.readbyqxmd.com/read/28726724/theoretical-studies-on-two-photon-fluorescent-hg-2-probes-based-on-the-coumarin-rhodamine-system
#7
Yujin Zhang, Jiancai Leng
The development of fluorescent sensors for Hg(2+) has attracted much attention due to the well-known adverse effects of mercury on biological health. In the present work, the optical properties of two newly-synthesized Hg(2+) chemosensors based on the coumarin-rhodamine system (named Pro1 and Pro2) were systematically investigated using time-dependent density functional theory. It is shown that Pro1 and Pro2 are effective ratiometric fluorescent Hg(2+) probes, which recognize Hg(2+) by Förster resonance energy transfer and through bond energy transfer mechanisms, respectively...
July 20, 2017: Sensors
https://www.readbyqxmd.com/read/28724786/emergent-cortical-circuit-dynamics-contain-dense-interwoven-ensembles-of-spike-sequences
#8
Joseph B Dechery, Jason N MacLean
Temporal codes are theoretically powerful encoding schemes, but their precise form in neocortex remains unknown in part because of the large number of possible codes and the difficulty in disambiguating informative spikes from statistical noise. A biologically plausible and computationally powerful temporal coding scheme is the Hebbian assembly phase sequence (APS), which predicts reliable propagation of spikes between functionally related assemblies of neurons. Here, we sought to measure the inherent capacity of neocortical networks to produce reliable sequences of spikes, as would be predicted by an APS code...
July 19, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28720885/two-photon-interference-of-polarization-entangled-photons-in-a-franson-interferometer
#9
Heonoh Kim, Sang Min Lee, Osung Kwon, Han Seb Moon
We present two-photon interference experiments with polarization-entangled photon pairs in a polarization-based Franson-type interferometer. Although the two photons do not meet at a common beamsplitter, a phase-insensitive Hong-Ou-Mandel type two-photon interference peak and dip fringes are observed, resulting from the two-photon interference effect between two indistinguishable two-photon probability amplitudes leading to a coincidence detection. A spatial quantum beating fringe is also measured for nondegenerate photon pairs in the same interferometer, although the two-photon states have no frequency entanglement...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28719207/elevation-of-the-energy-threshold-for-isomerization-of-5-hydroxyindole-tert-butyl-alcohol-1-cluster-cations
#10
Takamasa Ikeda, Kenji Sakota, Hiroshi Sekiya
Isomerization between two hydrogen-bonded (H-bonded) isomers of 5-hydroxyindole-(tert-butyl alcohol)1 cluster cations ([5HI-(t-BuOH)1](+)) was investigated in the gas phase. In the S0 state, jet-cooled 5HI-(t-BuOH)1 has two structural isomers, 5HI(OH)-(t-BuOH)1 and 5HI(NH)-(t-BuOH)1, in which the t-BuOH molecule is bound to the OH or the NH group of 5HI. The IR photodissociation spectrum of [5HI-(t-BuOH)1](+) generated by two-color resonant two-photon ionization (2C-R2PI) via the S1-S0 origin of 5HI(NH)-(t-BuOH)1 provided evidence of both [5HI(OH)-(t-BuOH)1](+) and [5HI(NH)-(t-BuOH)1](+) coexisting in the D0 state, indicating that [5HI(NH)-(t-BuOH)1](+) isomerizes to [5HI(OH)-(t-BuOH)1](+) after 2C-R2PI of 5HI(NH)-(t-BuOH)1...
July 18, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28717572/multiphoton-microscopy-for-label-free-identification-of-intramural-metastasis-in-human-esophageal-squamous-cell-carcinoma
#11
Jian Xu, Deyong Kang, Yaping Zeng, Shuangmu Zhuo, Xiaoqin Zhu, Liwei Jiang, Jianxin Chen, Jiangbo Lin
For complete removal of cancerous tissue in esophageal squamous cell carcinoma (ESCC), intramural metastasis (IM) should be identified preoperatively or intraoperatively. Here, multiphoton microscopy (MPM) was introduced for label-free identification of IM in the esophageal wall, by a combination of two-photon excited fluorescence (TPEF), second harmonic generation (SHG) imaging, and spectral analysis. Three-dimensional (3D) imaging of the IM region was also performed. Quantitative parameters, including 3D fiber orientation, were measured by 3D-weighted orientation vector summation...
July 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28717558/single-pulse-two-photon-fluorescence-lifetime-imaging-sp-flim-with-mhz-pixel-rate
#12
Matthias Eibl, Sebastian Karpf, Daniel Weng, Hubertus Hakert, Tom Pfeiffer, Jan Philip Kolb, Robert Huber
Two-photon-excited fluorescence lifetime imaging microscopy (FLIM) is a chemically specific 3-D sensing modality providing valuable information about the microstructure, composition and function of a sample. However, a more widespread application of this technique is hindered by the need for a sophisticated ultra-short pulse laser source and by speed limitations of current FLIM detection systems. To overcome these limitations, we combined a robust sub-nanosecond fiber laser as the excitation source with high analog bandwidth detection...
July 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28716943/visualizing-context-dependent-calcium-signaling-in-encephalitogenic-t-cells-in-vivo-by-two-photon-microscopy
#13
Nikolaos I Kyratsous, Isabel J Bauer, Guokun Zhang, Marija Pesic, Ingo Bartholomäus, Marsilius Mues, Ping Fang, Miriam Wörner, Stephanie Everts, Joachim W Ellwart, Joanna M Watt, Barry V L Potter, Reinhard Hohlfeld, Hartmut Wekerle, Naoto Kawakami
In experimental autoimmune encephalitis (EAE), autoimmune T cells are activated in the periphery before they home to the CNS. On their way, the T cells pass through a series of different cellular milieus where they receive signals that instruct them to invade their target tissues. These signals involve interaction with the surrounding stroma cells, in the presence or absence of autoantigens. To portray the serial signaling events, we studied a T-cell-mediated model of EAE combining in vivo two-photon microscopy with two different activation reporters, the FRET-based calcium biosensor Twitch1 and fluorescent NFAT...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28714201/encoding-random-hot-spots-of-a-volume-gold-nanorod-assembly-for-ultralow-energy-memory
#14
Qiaofeng Dai, Min Ouyang, Weiguang Yuan, Jinxiang Li, Banghong Guo, Sheng Lan, Songhao Liu, Qiming Zhang, Guang Lu, Shaolong Tie, Haidong Deng, Yi Xu, Min Gu
Data storage with ultrahigh density, ultralow energy, high security, and long lifetime is highly desirable in the 21st century and optical data storage is considered as the most promising way to meet the challenge of storing big data. Plasmonic coupling in regularly arranged metallic nanoparticles has demonstrated its superior properties in various applications due to the generation of hot spots. Here, the discovery of the polarization and spectrum sensitivity of random hot spots generated in a volume gold nanorod assembly is reported...
July 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28712570/electron-microscopic-reconstruction-of-functionally-identified-cells-in-a-neural-integrator
#15
Ashwin Vishwanathan, Kayvon Daie, Alexandro D Ramirez, Jeff W Lichtman, Emre R F Aksay, H Sebastian Seung
Neural integrators are involved in a variety of sensorimotor and cognitive behaviors. The oculomotor system contains a simple example, a hindbrain neural circuit that takes velocity signals as inputs and temporally integrates them to control eye position. Here we investigated the structural underpinnings of temporal integration in the larval zebrafish by first identifying integrator neurons using two-photon calcium imaging and then reconstructing the same neurons through serial electron microscopic analysis...
July 24, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28710672/automated-3-d-detection-of-dendritic-spines-from-in-vivo-two-photon-image-stacks
#16
P K Singh, P Hernandez-Herrera, D Labate, M Papadakis
Despite the significant advances in the development of automated image analysis algorithms for the detection and extraction of neuronal structures, current software tools still have numerous limitations when it comes to the detection and analysis of dendritic spines. The problem is especially challenging in in vivo imaging, where the difficulty of extracting morphometric properties of spines is compounded by lower image resolution and contrast levels native to two-photon laser microscopy. To address this challenge, we introduce a new computational framework for the automated detection and quantitative analysis of dendritic spines in vivo multi-photon imaging...
July 14, 2017: Neuroinformatics
https://www.readbyqxmd.com/read/28709993/intracellular-calcium-release-through-ip3r-or-ryr-contributes-to-secondary-axonal-degeneration
#17
Ben C Orem, Nicolas Pelisch, Joshua Williams, Jacqueline M Nally, David P Stirling
Severed CNS axons often retract or dieback away from the injury site and fail to regenerate. The precise mechanisms underlying acute axonal dieback and secondary axonal degeneration remain poorly understood. Here we investigate the role of Ca(2+) store mediated intra-axonal Ca(2+) release in acute axonal dieback and secondary axonal degeneration. To differentiate between primary (directly transected) and "bystander" axonal injury (axons spared by the initial injury but then succumb to secondary degeneration) in real-time we use our previously published highly focal laser-induced spinal cord injury (LiSCI) ex vivo model...
July 12, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28709138/multimodal-nonlinear-microscope-based-on-a-compact-fiber-format-laser-source
#18
Francesco Crisafi, Vikas Kumar, Antonio Perri, Marco Marangoni, Giulio Cerullo, Dario Polli
We present a multimodal non-linear optical (NLO) laser-scanning microscope, based on a compact fiber-format excitation laser and integrating coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS) and two-photon-excitation fluorescence (TPEF) on a single platform. We demonstrate its capabilities in simultaneously acquiring CARS and SRS images of a blend of 6-μm poly(methyl methacrylate) beads and 3-μm polystyrene beads. We then apply it to visualize cell walls and chloroplast of an unprocessed fresh leaf of Elodea aquatic plant via SRS and TPEF modalities, respectively...
July 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28706994/short-range-surface-plasmonics-localized-electron-emission-dynamics-from-a-60-nm-spot-on-an-atomically-flat-single-crystalline-gold-surface
#19
Bettina Frank, Philip Kahl, Daniel Podbiel, Grisha Spektor, Meir Orenstein, Liwei Fu, Thomas Weiss, Michael Horn-von Hoegen, Timothy J Davis, Frank-J Meyer Zu Heringdorf, Harald Giessen
We experimentally and theoretically visualize the propagation of short-range surface plasmon polaritons using atomically flat single-crystalline gold platelets on silicon substrates. We study their excitation and subfemtosecond dynamics via normal-incidence two-photon photoemission electron microscopy. By milling a plasmonic disk and grating structure into a single-crystalline gold platelet, we observe nanofocusing of the short-range surface plasmon polariton. Localized two-photon ultrafast electron emission from a spot with a smallest dimension of 60 nm is observed...
July 2017: Science Advances
https://www.readbyqxmd.com/read/28700575/synaptic-organization-of-visual-space-in-primary-visual-cortex
#20
M Florencia Iacaruso, Ioana T Gasler, Sonja B Hofer
How a sensory stimulus is processed and perceived depends on the surrounding sensory scene. In the visual cortex, contextual signals can be conveyed by an extensive network of intra- and inter-areal excitatory connections that link neurons representing stimulus features separated in visual space. However, the connectional logic of visual contextual inputs remains unknown; it is not clear what information individual neurons receive from different parts of the visual field, nor how this input relates to the visual features that a neuron encodes, defined by its spatial receptive field...
July 12, 2017: Nature
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