Bulletin of the American Physical Society
2018 Annual Meeting of the APS Mid-Atlantic Section
Volume 63, Number 20
Friday–Sunday, November 9–11, 2018; College Park, Maryland
Session G03: Biophysics |
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Chair: Hacene Boukari, Delaware State University Room: Edward St. John 1224 |
Saturday, November 10, 2018 4:00PM - 4:36PM |
G03.00001: Probing the role of tissue biophysics in metastasis Invited Speaker: Kandice Danielle Tanner Tissue homeostasis and malignant transformation are modulated by the reciprocal crosstalk between cells and the surrounding extracellular matrix (ECM), which encompasses both long-term matrix organization and short-term biochemical responses. I will present data obtained using broad band optical trap- active microrheology to probe the microscale rigidity and viscoelasticity at locations inside the cell cytoplasm and in the surrounding 3D ECM. These measurements were acquired with near simultaneity and at high frequencies relevant to molecular dynamics. A mechanical mismatch wherein the tumor cells are more rigid than the surrounding ECM was observed. In the frequency regime about the terminal relaxation time, both intracellular and extracellular measurements of the microscale rigidity relate to oscillation frequency by monomial power laws in the range 400 Hz – 15 kHz independent of type of matrix and perturbation of the cytoskeletal dynamics. These data also extend the frequency range revealing a stronger power law dependence for both intracellular and the coupled extracellular mechanics. The exponents and coefficients of these power laws are anti-correlated and collapse onto master curves. These data suggest that there is a mismatch between cells and the ECM when cells are cultured in 3D mimetics in the frequency range at which single filament dynamics emerge. |
Saturday, November 10, 2018 4:36PM - 5:12PM |
G03.00002: New viscoelastic materials for more realistic cell biology Invited Speaker: Paul A Janmey Hydrogels are increasingly used in cell biologic studies in order to cultivate cells on soft surfaces that more closely mimic the physiological environment than rigid glass or plastic surfaces. Such studies have revealed how changes in the elastic properties of substrates impact cell structure and function. Real biological tissues are not only elastic, but they also have viscous properties that dissipate cell-generated forces. Cellular responses to the viscous aspects of their substrates are much less well characterized, in part because of the lack materials with independently tunable elastic and viscous moduli. We have developed a method to make viscoelastic gels with mechanical properties resembling soft biological tissues, and suitable for cell culture in vitro. These gels can be used for traction force microscopy experiments. Use of these new materials demonstrates that multiple cell types respond to the viscoelasticity of their substrate and that viscous dissipation has an influence on cell spreading, contractility and motility. Differences in the effect of viscous dissipation on normal and transformed cells might help define the abnormalities that occur in diseased tissues. |
Saturday, November 10, 2018 5:12PM - 5:48PM |
G03.00003: Modeling the spatial and temporal responses of the human thalamus Invited Speaker: Keith Schneider The thalamus is an important subcortical structure that regulates the flow of information throughout the brain. Most of the interesting perceptual processes operate at time scales one or two orders of magnitude faster than the temporal resolution of functional magnetic resonance imaging (fMRI). However, despite the sluggishness of the hemodynamic response measured by fMRI, it is still possible to study temporal processing in deep structures in the human brain through analysis of aggregate and modeled population responses. I will present the results of some of our recent work investigating the temporal frequency responses and transient/sustained channels in the human lateral geniculate nucleus (LGN) and thalamic reticular nucleus. We are able to segment the magno- and parvocellular sections of the LGN based on temporal response properties. These results will help us to understand the dynamics and fundamental mechanisms of perception. |
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