Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D10: Optics Across Biological and Medical PhysicsFocus Recordings Available
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Sponsoring Units: DBIO GMED Chair: Wojciech Zbijewski, Johns Hopkins University Room: McCormick Place W-181A |
Monday, March 14, 2022 3:00PM - 3:12PM |
D10.00001: Small angle x-ray scattering with photon counting spectral detectors and their novel applications in biophysics and imaging Mini Das, Juan Carlos R Luna Small angle x-ray scattering (SAXS) techniques measure elastic x-ray scattering, which provide microstructural information and unique signatures of biomaterials and samples. However this technique is often limited by the need for high flux (often found in synchrotrons) and the need for high collimation of beam and small samples. Recent advances of direct conversion semiconductor detectors with photon counting capabilities offer new avenues in SAXS. We will show the benefits and describe applications of a cutting edge photon counting detector (PCD) developed by the CERN Medipix collaboration. This detector processes up to 40M hits/cm2/s when operated in data-driven mode. It allows readout of pixel coordinate, time-over-threshold(TOT) and time of arrival (TOA) immediately after a photon hits a pixel, while the other pixels remain sensitive. The detector efficiency, enhanced spatial resolution and true spectroscopic capabilities of this family of detectors provide unique features that make it ideal for SAXS applications. |
Monday, March 14, 2022 3:12PM - 3:48PM |
D10.00002: 3D and 4D computational imaging of molecular orientation with multiview polarized fluorescence microscopy Invited Speaker: Patrick La Riviere If a fluorophore is rigidly attached to a molecule of interest, then the orientation of the fluorophore can report valuable information about the orientation and diffusive behavior of the molecule. To measure and interpret this information in living cells we have developed a new set of techniques for imaging and reconstructing the position and orientation of fluorophores throughout a three-dimensional sample. These techniques consist of a multiview, polarized-illumination light sheet microscope coupled with novel computational models that relate the measured intensities to the orientation distribution function of fluorophores at each voxel. These new models, when expanded in a basis of complex exponentials and spherical harmonics, give insight into the capabilities of the imaging system and also provide a framework for efficient solution of the inverse problem. |
Monday, March 14, 2022 3:48PM - 4:24PM |
D10.00003: Phase Imaging Across Length and Depth Scales for Biophysics and Medical Applications Invited Speaker: Mini Das Phase contrast optical imaging allows enhanced contrast with imaging geometries that utilize the wave nature of light. Optical instrumentation and computational imaging algorithms are |
Monday, March 14, 2022 4:24PM - 4:36PM |
D10.00004: High-sensitive Phase Microscopy for Biological Sensing. Dominika Lyzwa, Zahid Yaqoob, Peter So Label-free optical imaging techniques have long been used for detection of neural activity. Current wide-field interferometric systems are limited due to their low phase measurement sensitivity. Here, we present a method to improve sensitivity by two orders of magnitude. Sensitivity is improved by utilizing the full dynamic range of the camera. Such high sensitivity phase measurements will allow single-shot optical sensing of neural action potentials via imaging of optical path length changes. Monitoring neuron activity within a neural network will allow us to better understand neural network processing. |
Monday, March 14, 2022 4:36PM - 4:48PM |
D10.00005: The Dynamics of Cancer Cells In Self-Generated Hypoxia Robert H Austin, Yihua Zhou, Junle Qiu, Sarah Amend, Kenneth J Pienta, Henry Wietfeldt, Allison Zhou, Joel Brown, Emma Hammarlund, Trung V Phan Hypoxia is context-dependent but, in tissue, loosely defined as oxygen concentrations below those that are physiologically normal (Ivanovic ref). In some cases, sudden hypoxia has been demonstrated to be a powerful driver of mutations in both bacteria and eukaryotic cells. The origin of the mutagenic nature of hypoxia is connected to basic cell metabolism pathways that can generate highly reactive singlet oxygen when perturbed under low oxygen conditions. Hypoxia is a common condition in a tumor \cite{tumor-hypoxia} because the rapid and uncontrolled growth of the tumor leads to a disorganized and inefficient vascular system to feed nutrients and oxygen to the tumor. We have developed a oxygen-permeable thin film containing a platinum-porphyrin phosphorescent dye whose excited state is quenched by O2. The dye phosphorescence intensity is a function of oxygen concentration over at least 3 orders of magnitude of concentration, when used in a microfabricated 3D ecology we get time and 2D space resolved hypoxia of a PC3 cancer colony. By quantifying the intensity of the image of the steady-state phosphoresence of the sensor film using a digital CCD camera, it is possible to image the oxygen concentration in a confluent layer of cancer cells under conditions where they generate their own high levels of hypoxia. Tracking the motion of cancer cells versus time in self-generated high hypoxia allows us to dtermine their response to high levels of hypoxia, both during the hypoxia and when it is released. |
Monday, March 14, 2022 4:48PM - 5:00PM |
D10.00006: Hyperspectral evaluation of tissue vasculature structure and oxygenation Jost Stergar, Katja Lakota, Martina Perše, Matija Tomšič, Matija Milanic Blood vessel network structure and function are important indicators of a disease. Hyperspectral imaging (HSI) is an optical imaging modality combining imaging and spectroscopy offering insight into tissue structure and biochemical processes. |
Monday, March 14, 2022 5:00PM - 5:12PM |
D10.00007: Infrared spectral phenotyping accurately predicts neurodegenerative disease class in the absence of overt symptoms Michael C Martin, Cynthia T McMurray, Lila Lovergne, Dhruba Ghosh, Renaud Schuck, Aris A Polyzos, Andrew Chen, Edward S Barnard, James B Brown Although some neurodegenerative diseases can be identified by behavioral characteristics relatively late in disease progression, we currently lack methods to predict who has developed disease before the onset of symptoms, when onset will occur, or the outcome of therapeutics. New biomarkers are needed. Here we describe spectral phenotyping, a new kind of biomarker that makes disease predictions based on chemical rather than biological endpoints in cells. Spectral phenotyping uses Fourier Transform Infrared (FTIR) spectromicroscopy to produce an absorbance signature as a rapid physiological indicator of disease state. FTIR spectromicroscopy has over the past been used in differential diagnoses of manifest disease. Here, we report that the unique FTIR chemical signature accurately predicts disease class in mice with high probability in the absence of brain pathology. In human cells, the FTIR biomarker accurately predicts neurodegenerative disease class using fibroblasts as surrogate cells, an exciting potential for dissease diagnosis particularly for hard to reach brain diseases. |
Monday, March 14, 2022 5:12PM - 5:24PM |
D10.00008: Co-localization of moving point like structures in confocal microscopy Christian Wimmenauer, Thomas Heinzel Co-localization of fast-moving vesicular structures in sequential acquisition mode displays a challenge as conventional pixel-based metrics as the Pearson correlation coefficient or the Manders coefficients tend to perform poorly under these circumstances. To address this issue, we performed object-based co-localization analysis to sequentially scanned confocal images and time series and tested these object -based methods against well-established metrics. To generate data for validation, the lysosomes of MCF-7 cells were co-labeled with RFP and GFP. To further test the procedures, organelles that are known to be spatially well separated were co-stained. Furthermore, to demonstrate the practical application of the object-based methods, cells with RFP labeled lysosomes were incubated with fluorescent carbon nanoparticles, suspected to enter the endo-lysosomal pathway. |
Monday, March 14, 2022 5:24PM - 5:36PM |
D10.00009: Photonics probing of structural alterations in Parkinson’s disease in human brain cells/tissues Fatemah Alharthi, Pinki Chahal, Mohammad Moshahid Khan, Prabhakar Pradhan |
Monday, March 14, 2022 5:36PM - 5:48PM |
D10.00010: Mechanical fluctuations in saccular hair cells by optical techniques Martín A Toderi, Dzmitry Vaido, Chia-Hsi J Lin, Dolores Bozovic Hair cells of the auditory and vestibular systems are capable of detecting sub-nanometer deflections due to vibrations. In certain species and under specific conditions, they are also known to spontaneously oscillate without external stimulation. Mechanical input is converted into electrical signals by mechanically gated ion channels that open upon the deflection of hair bundles located on top of the hair cell somae. We studied in vitro the mechanical fluctuations occurring inside of hair cells from the sacculus of the American bullfrog under different conditions. The hair cells were analyzed by wide field light microscopy, obtaining optical sections. Spatial distribution of light intensity was recorded, as a means of tracking movement of various sub-cellular structures. We observed hair cells during spontaneous oscillations of the hair bundle and under stimulation of the efferent nerves. These conditions were achieved by properly adjusting the immersion solutions and employing a suction electrode for neuronal activation. Prominent mechanical motion was registered in the lower area of the cell body, close to where the synaptic boutons from innervating neurons are located. This indicates the presence of active motility in the hair cell soma, which has not hitherto been reported. |
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