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Yukiko Ikeuchi, Haruka Kogiso, Shigekuni Hosogi, Saori Tanaka, Chikao Shimamoto, Toshio Inui, Takashi Nakahari, Yoshinori Marunaka
MQAE is a 'non-ratiometric' chloride ion (Cl-)-quenched fluorescent indicator that is used to determine intracellular Cl- concentration ([Cl-]i). MQAE-based two-photon microscopy is reported to be a useful method to measure [Cl-]i, but it is still controversial because a change in cell volume may alter the MQAE concentration, leading to a change in the fluorescence intensity without any change in [Cl-]i. In an attempt to elucidate the effect or lack of effect of cell volume on MQAE concentration, we studied the effects of changes in cell volume, achieved by applying different levels of osmotic stress, on the intensity of MQAE fluorescence in airway ciliary cells...
January 13, 2018: Journal of Physiological Sciences: JPS
Ana Batista, Hans Georg Breunig, Aisada König, Andreas Schindele, Tobias Hager, Berthold Seitz, António Miguel Morgado, Karsten König
Purpose: The purpose of this study was to evaluate the feasibility of using two-photon imaging (TPI) to assess the condition of human corneas for transplantation. Methods: Human corneas were imaged after different storage times: short-term (STS), medium-term (MTS), and long-term (LTS) storage. A high-resolution, custom-built 5-dimensional multiphoton microscope with 12-fs pulsed laser excitation was used for image acquisition. Results: Optical discrimination between different corneal layers and sublayers based on their morphologic characteristics revealed by two-photon autofluorescence (AF) is possible...
January 1, 2018: Investigative Ophthalmology & Visual Science
Koji Ikezoe, Mahya Amano, Shinji Nishimoto, Ichiro Fujita
In vivo calcium (Ca2+) imaging using two-photon microscopy allows activity to be monitored simultaneously from hundreds of individual neurons within a local population. While this allows us to gain important insights into how cortical neurons represent sensory information, factors such as photo-bleaching of the Ca2+ indicator limit imaging duration (and thus the numbers of stimuli that can be tested), which in turn hampers the full characterization of neuronal response properties. Here, we demonstrate that using an encoding model combined with presentation of natural movies results in detailed characterization of receptive field (RF) properties despite the relatively short time for data collection...
January 10, 2018: NeuroImage
Christopher Schnaitmann, Väinö Haikala, Eva Abraham, Vitus Oberhauser, Thomas Thestrup, Oliver Griesbeck, Dierk F Reiff
Color vision extracts spectral information by comparing signals from photoreceptors with different visual pigments. Such comparisons are encoded by color-opponent neurons that are excited at one wavelength and inhibited at another. Here, we examine the circuit implementation of color-opponent processing in the Drosophila visual system by combining two-photon calcium imaging with genetic dissection of visual circuits. We report that color-opponent processing of UVshort/blue and UVlong/green is already implemented in R7/R8 inner photoreceptor terminals of "pale" and "yellow" ommatidia, respectively...
January 11, 2018: Cell
Yong Sup Ihn, Yosep Kim, Vincenzo Tamma, Yoon-Ho Kim
We report the observation of a counterintuitive phenomenon in multipath correlation interferometry with thermal light. The intensity correlation between the outputs of two unbalanced Mach-Zehnder interferometers (UMZIs) with two classically correlated beams of thermal light at the input exhibits genuine second-order interference with the visibility of 1/3. Surprisingly, the second-order interference does not degrade at all no matter how much the path length difference in each UMZI is increased beyond the coherence length of the thermal light...
December 29, 2017: Physical Review Letters
Davide Raffaele Ceratti, Yevgeny Rakita, Lorenzo Cremonesi, Ron Tenne, Vyacheslav Kalchenko, Michael Elbaum, Dan Oron, Marco Alberto Carlo Potenza, Gary Hodes, David Cahen
Self-healing, where a modification in some parameter is reversed with time without any external intervention, is one of the particularly interesting properties of halide perovskites. While there are a number of studies showing such self-healing in perovskites, they all are carried out on thin films, where the interface between the perovskite and another phase (including the ambient) is often a dominating and interfering factor in the process. Here, self-healing in perovskite (methylammonium, formamidinium, and cesium lead bromide (MAPbBr3 , FAPbBr3 , and CsPbBr3 )) single crystals is reported, using two-photon microscopy to create damage (photobleaching) ≈110 µm inside the crystals and to monitor the recovery of photoluminescence after the damage...
January 12, 2018: Advanced Materials
Jun Zhang, Hao Ouyang, Xin Zheng, Jie You, Runze Chen, Tong Zhou, Yizhen Sui, Yu Liu, Xiang'ai Cheng, Tian Jiang
The newly raised two-dimensional material MoS2 is regarded as an ideal candidate for saturated absorbers. Here, the open-aperture Z-scan method is used to study the saturation absorption (SA) response of monolayer and multilayer MoS2, considering laser irradiation with different pulse widths. Specifically, in cases of 10 ns and 10 ps laser pulses, the accumulative nonlinearity [e.g., free carrier absorption (FCA)] coupled with SA is found in both monolayer and multilayer MoS2. However, under a 65 fs pulse laser, the instantaneous nonlinearity [e...
January 15, 2018: Optics Letters
Y Li, D B Fullager, E Angelbello, D Childers, G Boreman, T Hofmann
Three-dimensional direct laser writing via two-photon polymerization is used to fabricate anti-reflective structured surfaces (ARSSs) composed of subwavelength conicoid features optimized to operate over a wide bandwidth in the near-infrared range from 3700  cm-1 to 6600  cm-1 (2.7-1.52 μm). Analytic Bruggemann effective medium calculations are used to predict nominal geometric parameters such as the fill factor of the constitutive conicoid features of the anti-reflective structured surfaces (ARSSs) presented here...
January 15, 2018: Optics Letters
Samuel A Meek, Arthur Hipke, Guy Guelachvili, Theodor W Hänsch, Nathalie Picqué
Sub-Doppler broadband multi-heterodyne spectroscopy is proposed and experimentally demonstrated. Using two laser frequency combs of slightly different repetition frequencies, we have recorded Doppler-free two-photon dual-comb spectra of atomic rubidium resonances of a width of 6 MHz, while simultaneously interrogating a spectral span of 10 THz. The atomic transitions are uniquely identified via the intensity modulation of the observed fluorescence radiation. To the best of our knowledge, these results represent the first demonstration of Doppler-free Fourier transform spectroscopy and extend the range of applications of broadband spectroscopy towards precision nonlinear spectroscopy...
January 1, 2018: Optics Letters
Lan Yang, Ke Wei, Zhongjie Xu, Feiming Li, Runze Chen, Xin Zheng, Xiangai Cheng, Tian Jiang
Recent progress in solar cell and light-emitting devices makes halide perovskite a research hot spot in optics. In this Letter, the nonlinear absorption and fluorescence properties of FAPbBr3 nanocrystal, one typical organometallic halide perovskite, have been investigated via Z-scan measurements and a density-dependent photoluminescence (PL) spectrum. The FAPbBr3 nanocrystal exhibits nonlinear absorption under the excitation of 800 nm, whose photon energy is below the bandgap of FAPbBr3. The significant absorption is experimentally confirmed to be induced by two-photon absorption (TPA), and the TPA coefficient is measured to be ∼0...
January 1, 2018: Optics Letters
Maximilian Hoffmann, Ioannis N Papadopoulos, Benjamin Judkewitz
The controlled modulation of an optical wavefront is required for aberration correction, digital phase conjugation, or patterned photostimulation. For most of these applications, it is desirable to control the wavefront modulation at the highest rates possible. The digital micromirror device (DMD) presents a cost-effective solution to achieve high-speed modulation and often exceeds the speed of the more conventional liquid crystal spatial light modulator but is inherently an amplitude modulator. Furthermore, spatial dispersion caused by DMD diffraction complicates its use with pulsed laser sources, such as those used in nonlinear microscopy...
January 1, 2018: Optics Letters
Irina Alexandra Paun, Roxana Cristina Popescu, Cosmin Catalin Mustaciosu, Marian Zamfirescu, Bogdan Stefanita Calin, Mona Mihailescu, Maria Dinescu, Andrei Popescu, Diana Georgiana Chioibasu, Mihai Sopronyi, Catalin Luculescu
A major limitation of existing 3D implantable structures for bone tissue engineering is that most of the cells rapidly attach on the outer edges of the structure, restricting the cells penetration into the inner parts and causing the formation of a necrotic core. Furthermore, these structures generally possess a random spatial arrangement and do not preserve the isotropy on the whole volume. Here, we report on the fabrication and testing of an innovative 3D hierarchical, honeycomb-like structure (HS), with reproducible and isotropic arhitecture, that allows "in volume" migration of osteoblasts...
January 12, 2018: Biofabrication
Finn Peters, Hazal Salihoglu, Eva Rodrigues, Etienne Herzog, Tanja Blume, Severin Filser, Mario Dorostkar, Derya R Shimshek, Nils Brose, Ulf Neumann, Jochen Herms
BACE1 is the rate-limiting protease in the production of synaptotoxic β-amyloid (Aβ) species and hence one of the prime drug targets for potential therapy of Alzheimer's disease (AD). However, so far pharmacological BACE1 inhibition failed to rescue the cognitive decline in mild-to-moderate AD patients, which indicates that treatment at the symptomatic stage might be too late. In the current study, chronic in vivo two-photon microscopy was performed in a transgenic AD model to monitor the impact of pharmacological BACE1 inhibition on early β-amyloid pathology...
January 11, 2018: Acta Neuropathologica
E Hasani, J Parravicini, L Tartara, A Tomaselli, D Tomassini
We propose an innovative experimental approach to estimate the two-photon absorption (TPA) spectrum of a fluorescent material. Our method develops the standard indirect fluorescence-based method for the TPA measurement by employing a line-shaped excitation beam, generating a line-shaped fluorescence emission. Such a configuration, which requires a relatively high amount of optical power, permits to have a greatly increased fluorescence signal, thus avoiding the photon counterdetection devices usually used in these measurements, and allowing to employ detectors such as charge-coupled device (CCD) cameras...
January 11, 2018: Journal of Microscopy
Sreekanth Perumbilavil, Alberto López-Ortega, Gaurav Kumar Tiwari, Josep Nogués, Tamio Endo, Reji Philip
Nonlinear optical nanostructured materials are gaining increased interest as optical limiters for various applications, although many of them suffer from reduced efficiencies at high-light fluences due to photoinduced deterioration. The nonlinear optical properties of ferrite core/shell nanoparticles showing their robustness for ultrafast optical limiting applications are reported. At 100 fs ultrashort laser pulses the effective two-photon absorption (2PA) coefficient shows a nonmonotonic dependence on the shell thickness, with a maximum value obtained for thin shells...
January 11, 2018: Small
Chang Su Lim, Myoung Ki Cho, Mi Yeon Park, Hwan Myung Kim
Hydrogen peroxide (H2O2) is important in the regulation of a variety of biological processes and is involved in various diseases. Quantitative measurement of H2O2 levels at the subcellular level is important for understanding its positive and negative effects on biological processes. Herein, a two-photon ratiometric fluorescent probe (SHP-Cyto) with a boronate-based carbamate leaving group as the H2O2 reactive trigger and 6-(benzo[d]thiazol-2'-yl)-2-(N,N-dimethylamino) naphthalene (BTDAN) as the fluorophore was synthesized and examined for its ability to detect cytosolic H2O2 in situ...
January 2018: ChemistryOpen
Saurav Seshadri, Andreas Klaus, Daniel E Winkowski, Patrick O Kanold, Dietmar Plenz
Disturbed activity patterns in cortical networks contribute to the pathophysiology of schizophrenia (SZ). Several lines of evidence implicate NMDA receptor hypofunction in SZ, and blocking NMDA receptor signaling during early neurodevelopment produces cognitive deficits in rodent models that resemble those seen in schizophrenic patients. However, the altered network dynamics underlying these cognitive impairments largely remain to be characterized, especially at the cellular level. Here, we use in vivo two-photon calcium imaging to describe pathological dynamics, occurring in parallel with cognitive dysfunction, in a developmental NMDA receptor hypofunction model...
January 10, 2018: Translational Psychiatry
Masahiro Wakabayashi, Daisuke Koketsu, Hideki Kondo, Shigeki Sato, Kiichi Ohara, Zlata Polyakova, Satomi Chiken, Nobuhiko Hatanaka, Atsushi Nambu
The common marmoset has been proposed as a potential alternative to macaque monkey as a primate model for neuroscience and medical research. Here, we have newly developed a stereotaxic neuronal recording system for awake marmosets under the head-fixed condition by modifying that for macaque monkeys. Using this system, we recorded neuronal activity in the cerebral cortex of awake marmosets and successfully identified the primary motor cortex by intracortical microstimulation. Neuronal activities of deep brain structures, such as the basal ganglia, thalamus, and cerebellum, in awake marmosets were also successfully recorded referring to magnetic resonance images...
January 6, 2018: Neuroscience Research
Lalit K Beura, Jason S Mitchell, Emily A Thompson, Jason M Schenkel, Javed Mohammed, Sathi Wijeyesinghe, Raissa Fonseca, Brandon J Burbach, Heather D Hickman, Vaiva Vezys, Brian T Fife, David Masopust
CD8+ T cell immunosurveillance dynamics influence the outcome of intracellular infections and cancer. Here we used two-photon intravital microscopy to visualize the responses of CD8+ resident memory T cells (TRM cells) within the reproductive tracts of live female mice. We found that mucosal TRM cells were highly motile, but paused and underwent in situ division after local antigen challenge. TRM cell reactivation triggered the recruitment of recirculating memory T cells that underwent antigen-independent TRM cell differentiation in situ...
January 8, 2018: Nature Immunology
Meng Wang, Ruijie Li, Jingcheng Li, Jianxiong Zhang, Xiaowei Chen, Shaoqun Zeng, Xiang Liao
In the primary auditory cortex (A1), neuronal ensembles are activated relative to anticipated sound events following rhythmic stimulation, but whether the echo responses of the neurons are related to their frequency selectivity remains unknown. Therefore, we used in vivo two-photon Ca2+ imaging to record the neuronal activities in the mouse A1 to elucidate the relationship between their echo responses and frequency selectivity. We confirmed the presence of echo responses in a subgroup of mouse Layer 2/3 A1 neurons following a train of rhythmic pure tone stimulation...
January 8, 2018: Scientific Reports
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