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Two photon microscopy

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https://www.readbyqxmd.com/read/28211922/applying-phasor-approach-analysis-of-multiphoton-flim-measurements-to-probe-the-metabolic-activity-of-three-dimensional-in-vitro-cell-culture-models
#1
Pirmin H Lakner, Michael G Monaghan, Yvonne Möller, Monilola A Olayioye, Katja Schenke-Layland
Fluorescence lifetime imaging microscopy (FLIM) can measure and discriminate endogenous fluorophores present in biological samples. This study seeks to identify FLIM as a suitable method to non-invasively detect a shift in cellular metabolic activity towards glycolysis or oxidative phosphorylation in 3D Caco-2 models of colorectal carcinoma. These models were treated with potassium cyanide or hydrogen peroxide as controls, and epidermal growth factor (EGF) as a physiologically-relevant influencer of cell metabolic behaviour...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211901/graphene-oxide-demonstrates-experimental-confirmation-of-abraham-pressure-on-solid-surface
#2
Anirban Kundu, Renu Rani, Kiran S Hazra
The century-old controversy over two contradicting theories on radiation pressure of light proposed by Abraham and Minkowski can come to an end if there is a direct method to measure the surface deformation of the target material due to momentum transfer of photons. Here we have investigated the effect of radiation pressure on the surface morphology of Graphene Oxide (GO) film, experienced due to low power focused laser irradiation. In-depth investigation has been carried out to probe the bending of the GO surface due to radiation pressure by Atomic Force Microscopy (AFM) and subsequently the uniaxial strain induced on the GO film has been probed by Raman Spectroscopy...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211891/experimental-observation-of-spatially-resolved-photo-luminescence-intensity-distribution-in-dual-mode-upconverting-nanorod-bundles
#3
Pawan Kumar, Satbir Singh, V N Singh, Nidhi Singh, R K Gupta, Bipin Kumar Gupta
A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho(3+)0.02/Yb(3+)0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211187/deletion-of-junctional-adhesion-molecule-a-from-platelets-increases-early-stage-neointima-formation-after-wire-injury-in-hyperlipidemic-mice
#4
Zhen Zhao, Tanja Vajen, Ela Karshovska, Annemiek Dickhout, Martin M Schmitt, Remco T A Megens, Philipp von Hundelshausen, Thomas A Koeppel, Tilman M Hackeng, Christian Weber, Rory R Koenen
Platelets play an important role in the pathogenesis of vascular remodelling after injury. Junctional adhesion molecule A (JAM-A) was recently described to regulate platelet activation. Specific deletion of JAM-A from platelets resulted in increased reactivity and in accelerated progression of atherosclerosis. The aim of this study was to investigate the specific contribution of platelet-derived JAM-A to neointima formation after vascular injury. Mice with or without platelet-specific (tr)JAM-A-deficiency in an apolipoprotein e (apoe(-/-) ) background underwent wire-induced injury of the common carotid artery...
February 17, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28199004/image-scanning-fluorescence-emission-difference-microscopy-based-on-a-detector-array
#5
Y Li, S Liu, D Liu, S Sun, C Kuang, Z Ding, X Liu
We propose a novel imaging method that enables the enhancement of three-dimensional resolution of confocal microscopy significantly and achieve experimentally a new fluorescence emission difference method for the first time, based on the parallel detection with a detector array. Following the principles of photon reassignment in image scanning microscopy, images captured by the detector array were arranged. And by selecting appropriate reassign patterns, the imaging result with enhanced resolution can be achieved with the method of fluorescence emission difference...
February 15, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28197343/chronic-social-defeat-stress-modulates-dendritic-spines-structural-plasticity-in-adult-mouse-frontal-association-cortex
#6
Yu Shu, Tonghui Xu
Chronic stress is associated with occurrence of many mental disorders. Previous studies have shown that dendrites and spines of pyramidal neurons of the prefrontal cortex undergo drastic reorganization following chronic stress experience. So the prefrontal cortex is believed to play a key role in response of neural system to chronic stress. However, how stress induces dynamic structural changes in neural circuit of prefrontal cortex remains unknown. In the present study, we examined the effects of chronic social defeat stress on dendritic spine structural plasticity in the mouse frontal association (FrA) cortex in vivo using two-photon microscopy...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/28191924/control-of-an-unusual-photo-claisen-rearrangement-in-coumarin-caged-tamoxifen-through-an-extended-spacer
#7
Pamela T Wong, Edward W Roberts, Shengzhuang Tang, Jhindan Mukherjee, Jayme Cannon, Alyssa J Nip, Kaitlin Corbin, Matthew F Krummel, Seok Ki Choi
The use of coumarin caged molecules has been well documented in numerous photocaging applications including for the spatiotemporal control of Cre-estrogen receptor (Cre-ERT2) recombinase activity. In this article, we report that 4-hydroxytamoxifen (4OHT) caged with coumarin via a conventional ether linkage led to an unexpected photo-Claisen rearrangement which significantly competed with the release of free 4OHT. The basis for this unwanted reaction appears to be related to the coumarin structure and its radical-based mechanism of uncaging as it did not occur in ortho-nitrobenzyl (ONB) caged 4OHT that was otherwise linked in the same manner...
February 13, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28190726/object-detecting-neurons-in-drosophila
#8
Mehmet F Keleş, Mark A Frye
Many animals rely on vision to detect objects such as conspecifics, predators, and prey. Hypercomplex cells found in feline cortex and small target motion detectors found in dragonfly and hoverfly optic lobes demonstrate robust tuning for small objects, with weak or no response to larger objects or movement of the visual panorama [1-3]. However, the relationship among anatomical, molecular, and functional properties of object detection circuitry is not understood. Here we characterize a specialized object detector in Drosophila, the lobula columnar neuron LC11 [4]...
January 30, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28181842/the-effects-of-hypercapnia-on-cortical-capillary-transit-time-heterogeneity-cth-in-anesthetized-mice
#9
Eugenio Gutiérrez-Jiménez, Hugo Angleys, Peter Mondrup Rasmussen, Irene Klærke Mikkelsen, Kim Mouridsen, Leif Østergaard
Capillary flow patterns are highly heterogeneous in the resting brain. During hyperemia, capillary transit-time heterogeneity (CTH) decreases, in proportion to blood's mean transit time (MTT) in passive, compliant microvascular networks. Previously, we found that functional activation reduces the CTH:MTT ratio, suggesting that additional homogenization takes place through active neurocapillary coupling mechanisms. Here, we examine changes in the CTH:MTT ratio during hypercapnic hyperemia in anesthetized mice (C57Bl/6NTac), expecting that homogenization is smaller than during functional hyperemia...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28181535/nanoscale-diffusion-in-the-synaptic-cleft-and-beyond-measured-with-time-resolved-fluorescence-anisotropy-imaging
#10
Kaiyu Zheng, Thomas P Jensen, Leonid P Savtchenko, James A Levitt, Klaus Suhling, Dmitri A Rusakov
Neural activity relies on molecular diffusion within nanoscopic spaces outside and inside nerve cells, such as synaptic clefts or dendritic spines. Measuring diffusion on this small scale in situ has not hitherto been possible, yet this knowledge is critical for understanding the dynamics of molecular events and electric currents that shape physiological signals throughout the brain. Here we advance time-resolved fluorescence anisotropy imaging combined with two-photon excitation microscopy to map nanoscale diffusivity in ex vivo brain slices...
February 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28170263/wavelength-dependent-second-harmonic-generation-circular-dichroism-for-differentiation-of-col-i-and-col-iii-isoforms-in-stromal-models-of-ovarian-cancer-based-on-intrinsic-chirality-differences
#11
Kirby R Campbell, Paul J Campagnola
Extensive remodeling of the extracellular matrix (ECM) occurs in many epithelial cancers, for example in ovarian cancer, upregulation of collagen isoform type III has been linked to invasive forms of the disease, and this change may be a potential biomarker. To examine this possibility, we implemented wavelength dependent Second Harmonic Generation Circular Dichroism (SHG-CD) imaging microscopy to quantitatively determine changes in chirality in ECM models comprised of different Col I/Col III composition. In these models, Col III was varied between 0% and 40%, and we found increasing Col III results in reduced net chirality, consistent with structural biology studies of Col I and III in tissues where the isoforms comingle in the same fibrils...
February 7, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28158009/sted-properties-of-ce-sup-3-sup-tb-sup-3-sup-and-eu-sup-3-sup-doped-inorganic-scintillators
#12
M S Alekhin, J Renger, M Kasperczyk, P-A Douissard, T Martin, Y Zorenko, D A Vasil'ev, M Stiefel, L Novotny, M Stampanoni
Scintillator-based X-ray imaging is a powerful technique for noninvasive real-space microscopic structural investigation such as synchrotron-based computed tomography. The resolution of an optical image formed by scintillation emission is fundamentally diffraction limited. To overcome this limit, stimulated scintillation emission depletion (SSED) X-ray imaging, based on stimulated emission depletion (STED) microscopy, has been recently developed. This technique imposes new requirements on the scintillator material: efficient de-excitation by the STED-laser and negligible STED-laser excited luminescence...
January 23, 2017: Optics Express
https://www.readbyqxmd.com/read/28156033/amplification-of-a-fret-probe-by-lipid-water-partition-for-the-detection-of-acid-sphingomyelinase-in-live-cells
#13
Thomas Pinkert, David Furkert, Thomas Korte, Andreas Herrmann, Christoph Arenz
Real-time monitoring of acid sphingomyelinase (ASM) activity is crucial for investigating its role in lipid-mediated signaling processes. In this study, we synthesized fluorescent phosphosphingolipids capable of FRET by phosphorodichloridate chemistry. These sphingomyelin analogues are substrates for recombinant human ASM and can be used to monitor ASM activity by fluorescence spectroscopy. Incubation with cell lysates from wild-type and knock-out mice further confirmed probe cleavage to be exclusive to ASM...
March 1, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28151646/three-dimensional-localization-of-single-molecules-for-super-resolution-imaging-and-single-particle-tracking
#14
Alex von Diezmann, Yoav Shechtman, W E Moerner
Single-molecule super-resolution fluorescence microscopy and single-particle tracking are two imaging modalities that illuminate the properties of cells and materials on spatial scales down to tens of nanometers or with dynamical information about nanoscale particle motion in the millisecond range, respectively. These methods generally use wide-field microscopes and two-dimensional camera detectors to localize molecules to much higher precision than the diffraction limit. Given the limited total photons available from each single-molecule label, both modalities require careful mathematical analysis and image processing...
February 2, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28146530/saturated-two-photon-excitation-fluorescence-microscopy-with-core-ring-illumination
#15
Ryosuke Oketani, Atsushi Doi, Nicholas I Smith, Yasunori Nawa, Satoshi Kawata, Katsumasa Fujita
We demonstrated resolution improvement in two-photon excitation microscopy by combining saturated excitation (SAX) of fluorescence and pupil manipulation. We theoretically estimated the resolution improvement and the sidelobe effect in the point spread function with various pupil designs and found that the combination of SAX and core-ring illumination can effectively enhance the spatial resolution in 3D and suppress sidelobe artifacts. The experimental demonstration shows that the proposed technique is effective for observation with a depth of 100 μm in a tissue phantom and can be applied to 3D observations of tissue samples with higher spatial resolution than conventional two-photon excitation microscopy...
February 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28139643/light-controls-cerebral-blood-flow-in-naive-animals
#16
Ravi L Rungta, Bruno-Félix Osmanski, Davide Boido, Mickael Tanter, Serge Charpak
Optogenetics is increasingly used to map brain activation using techniques that rely on functional hyperaemia, such as opto-fMRI. Here we test whether light stimulation protocols similar to those commonly used in opto-fMRI or to study neurovascular coupling modulate blood flow in mice that do not express light sensitive proteins. Combining two-photon laser scanning microscopy and ultrafast functional ultrasound imaging, we report that in the naive mouse brain, light per se causes a calcium decrease in arteriolar smooth muscle cells, leading to pronounced vasodilation, without excitation of neurons and astrocytes...
January 31, 2017: Nature Communications
https://www.readbyqxmd.com/read/28137973/a-critical-role-for-astrocytes-in-hypercapnic-vasodilation-in-brain
#17
C Howarth, B A Sutherland, H B Choi, C Martin, B L Lind, L Khennouf, J M LeDue, J M P Pakan, R W Ko, G C R Ellis-Davies, M J Lauritzen, N R Sibson, A M Buchan, B A MacVicar
: Cerebral blood flow (CBF) is controlled by arterial blood pressure, arterial CO2, arterial O2, and brain activity and is largely constant in the awake state. Although small changes in arterial CO2 are particularly potent to change CBF (1 mmHg variation in arterial CO2 changes CBF by 3-4%), the coupling mechanism is incompletely understood. We tested the hypothesis that astrocytic prostaglandin E2 (PgE2) plays a key role for cerebrovascular CO2 reactivity and that preserved synthesis of glutathione is essential for the full development of this response...
January 30, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28133923/a-comparative-study-of-ex-vivo-skin-optical-clearing-using-two-photon-microscopy
#18
Anton Sdobnov, Maxim E Darvin, Juergen Lademann, Valery Tuchin
Multiphoton tomography (MPT) is a prospective tool for imaging the skin structure. Aiming to increase the probing depth, a comparative ex vivo study of optical clearing of porcine ear skin was performed by using two optical clearing agents (OCAs), i.e., glycerol and iohexol (Omnipaque(TM) ) at different concentrations, which exhibit different osmotic properties. The results show that a topical application of glycerol or Omnipaque(TM) solutions onto the skin for 60 min significantly improved the depth and contrast of the MPT signals...
January 30, 2017: Journal of Biophotonics
https://www.readbyqxmd.com/read/28129796/two-photon-flim-of-nad-p-h-and-fad-in-mesenchymal-stem-cells-undergoing-either-osteogenic-or-chondrogenic-differentiation
#19
Aleksandra V Meleshina, Varvara V Dudenkova, Alena S Bystrova, Daria S Kuznetsova, Marina V Shirmanova, Elena V Zagaynova
BACKGROUND: Metabolic plasticity and the versatility of different lineages of stem cells as they satisfy their energy demands are not completely understood. In this study we investigated the metabolic changes in mesenchymal stem cells (MSCs) undergoing differentiation in two directions, osteogenic and chondrogenic, using two-photon fluorescence microscopy combined with FLIM. METHODS: Differentiation was induced by incubating the human bone marrow MSCs in osteogenic or chondrogenic mediums...
January 28, 2017: Stem Cell Research & Therapy
https://www.readbyqxmd.com/read/28128537/inverted-multiscale-optical-resolution-photoacoustic-microscopy
#20
Weizhi Qi, Tian Jin, Jian Rong, Huabei Jiang, Lei Xi
Optical resolution photoacoustic microscopy (ORPAM) is one of the fastest evolving photoacoustic imaging modalities. It not only has a comparable spatial resolution to pure optical microscopies such as epifluorescence microscopy, confocal microscopy, and two-photon microscopy, but also owns a higher penetration depth. In this study, we report an inverted multiscale (IM)-ORPAM that utilizes a two-dimensional galvanometric scanner integrated with two microscopic imaging lenses to achieve rotary-scanning-based multiscale imaging...
January 27, 2017: Journal of Biophotonics
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