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Full-Text Articles in Physics

Extracellular Vimentin As A Target Against Sars-Cov-2 Host Cell Invasion, Łukasz Suprewicz, Maxx Swoger, Sarthak Gupta, Ewelina Piktel, Fitzroy J. Byfield, Daniel V. Iwamoto, Danielle Germann, Joanna Reszeć, Natalia Marcińczyk, Robert J. Carroll, Paul A. Janmey, J. M. Schwarz, Robert Bucki, Alison E. Patteson Dec 2021

Extracellular Vimentin As A Target Against Sars-Cov-2 Host Cell Invasion, Łukasz Suprewicz, Maxx Swoger, Sarthak Gupta, Ewelina Piktel, Fitzroy J. Byfield, Daniel V. Iwamoto, Danielle Germann, Joanna Reszeć, Natalia Marcińczyk, Robert J. Carroll, Paul A. Janmey, J. M. Schwarz, Robert Bucki, Alison E. Patteson

Physics - All Scholarship

Infection of human cells by pathogens, including SARS-CoV-2, typically proceeds by cell surface binding to a crucial receptor. The primary receptor for SARS-CoV-2 is the angiotensin-converting enzyme 2 (ACE2), yet new studies reveal the importance of additional extracellular co-receptors that mediate binding and host cell invasion by SARS-CoV-2. Vimentin is an intermediate filament protein that is increasingly recognized as being present on the extracellular surface of a subset of cell types, where it can bind to and facilitate pathogens’ cellular uptake. Biophysical and cell infection studies are done to determine whether vimentin might bind SARS-CoV-2 and facilitate its uptake. Dynamic …


A Data-Driven Statistical Description For The Hydrodynamics Of Active Matter, Ahmad Borzou, Alison E. Patteson, J. M. Schwarz Oct 2021

A Data-Driven Statistical Description For The Hydrodynamics Of Active Matter, Ahmad Borzou, Alison E. Patteson, J. M. Schwarz

Physics - All Scholarship

Modeling living systems at the collective scale can be very challenging because the individual constituents can themselves be complex and the respective interactions between the constituents may not be fully understood. With the advent of high throughput experiments and in the age of big data, data-driven methods are on the rise to overcome these challenges. Although machine-learning approaches can help quantify correlations between the various players, they do not directly shed light on the underlying physical principles of such systems. Here, we present a data-driven method for obtaining the phase-space density of active matter systems such that the solution to …


The Role Of Vimentin–Nuclear Interactions In Persistent Cell Motility Through Confined Spaces, Sarthak Gupta, Alison E. Patteson, J. M. Schwarz Sep 2021

The Role Of Vimentin–Nuclear Interactions In Persistent Cell Motility Through Confined Spaces, Sarthak Gupta, Alison E. Patteson, J. M. Schwarz

Physics - All Scholarship

The ability of cells to move through small spaces depends on the mechanical properties of the cellular cytoskeleton and on nuclear deformability. In mammalian cells, the cytoskeleton is composed of three interacting, semi-flexible polymer networks: actin, microtubules, and intermediate filaments (IF). Recent experiments of mouse embryonic fibroblasts with and without vimentin have shown that the IF vimentin plays a role in confined cell motility. Here, we develop a minimal model of a cell moving through a microchannel that incorporates explicit effects of actin and vimentin and implicit effects of microtubules. Specifically, the model consists of a cell with an actomyosin …


Photovoltages In Polycrystalline Mosaic Solar Cells, Steluta A. Dinca, Eric A. Schiff Jul 2021

Photovoltages In Polycrystalline Mosaic Solar Cells, Steluta A. Dinca, Eric A. Schiff

Chemistry - All Scholarship

In some thin-film solar cells the light-absorbing layer is a mosaic of crystalline grains whose boundaries run from the back to the front of the cell. We used the semiconductor modeling software Sesame to do numerical calculations of the optoelectronic properties of such cells assuming that recombination of minority photocarriers occurs primarily at the grain boundaries. The work complements analytical results for diffusion-limited recombination at grain boundaries and dislocations. We chose idealized n-CdS/p-CdTe solar cells for illustration. We find that the open-circuit voltage, Voc, under illumination declines logarithmically with increasing ratio D/θ2, where D is the …


Dynamic Nuclear Structure Emerges From Chromatin Cross-Links And Motors, Kuang Liu, Alison E. Patteson, Edward J. Banigan, J. M. Schwarz Apr 2021

Dynamic Nuclear Structure Emerges From Chromatin Cross-Links And Motors, Kuang Liu, Alison E. Patteson, Edward J. Banigan, J. M. Schwarz

Physics - All Scholarship

The cell nucleus houses the chromosomes, which are linked to a soft shell of lamin protein filaments. Experiments indicate that correlated chromosome dynamics and nuclear shape fluctuations arise from motor activity. To identify the physical mechanisms, we develop a model of an active, cross-linked Rouse chain bound to a polymeric shell. System-sized correlated motions occur but require both motor activity and cross-links. Contractile motors, in particular, enhance chromosome dynamics by driving anomalous density fluctuations. Nuclear shape fluctuations depend on motor strength, cross-linking, and chromosome-lamina binding. Therefore, complex chromosome dynamics and nuclear shape emerge from a minimal, active chromosome-lamina system.


Cell-Induced Confinement Effects In Soft Tissue Mechanics, Dawei Song, Jordan L. Shivers, Fred C. Mackintosh, Alison E. Patteson, Paul A. Janmey Apr 2021

Cell-Induced Confinement Effects In Soft Tissue Mechanics, Dawei Song, Jordan L. Shivers, Fred C. Mackintosh, Alison E. Patteson, Paul A. Janmey

Physics - All Scholarship

The mechanical properties of tissues play a critical role in their normal and pathophysiological functions such as tissue development, aging, injury, and disease. Understanding tissue mechanics is important not only for designing realistic biomimetic materials for tissue engineering and drug testing but also for developing novel diagnostic techniques and medical interventions. Tissues are heterogeneous materials consisting of cells confined within extracellular matrices (ECMs), both of which derive their structural integrity, at least in part, from networks of biopolymers. However, the rheology of purified reconstituted biopolymer networks fails to explain many key aspects of tissue mechanics. Notably, purified networks typically soften …


Vimentin Tunes Cell Migration On Collagen By Controlling Β1 Integrin Activation And Clustering, Zofia Ostrowska-Podhorodecka, Isabel Ding, Wilson Lee, Jelena Tanic, Sevil Abbasi, Pamma D. Arora, Richard S. Liu, Alison E. Patteson, Paul A. Janmey, Christopher A. Mcculloch Mar 2021

Vimentin Tunes Cell Migration On Collagen By Controlling Β1 Integrin Activation And Clustering, Zofia Ostrowska-Podhorodecka, Isabel Ding, Wilson Lee, Jelena Tanic, Sevil Abbasi, Pamma D. Arora, Richard S. Liu, Alison E. Patteson, Paul A. Janmey, Christopher A. Mcculloch

Physics - All Scholarship

Vimentin is a structural protein that is required for mesenchymal cell migration and directly interacts with actin, β1 integrin and paxillin. We examined how these interactions enable vimentin to regulate cell migration on collagen. In fibroblasts, depletion of vimentin increased talin-dependent activation of β1 integrin by more than 2-fold. Loss of vimentin was associated with reduction of β1 integrin clustering by 50% and inhibition of paxillin recruitment to focal adhesions by more than 60%, which was restored by vimentin expression. This reduction of paxillin was associated with 65% lower Cdc42 activation, a 60% reduction of cell extension formation and a …


Bacterial Activity Hinders Particle Sedimentation, Jaspreet Singh, Alison E. Patteson, Bryan O. Torres Maldonado, Prashant K. Purohit, Paulo E. Arratia Mar 2021

Bacterial Activity Hinders Particle Sedimentation, Jaspreet Singh, Alison E. Patteson, Bryan O. Torres Maldonado, Prashant K. Purohit, Paulo E. Arratia

Physics - All Scholarship

Sedimentation in active fluids has come into focus due to the ubiquity of swimming micro-organisms in natural and industrial processes. Here, we investigate sedimentation dynamics of passive particles in a fluid as a function of bacteria E. coli concentration. Results show that the presence of swimming bacteria significantly reduces the speed of the sedimentation front even in the dilute regime, in which the sedimentation speed is expected to be independent of particle concentration. Furthermore, bacteria increase the dispersion of the passive particles, which determines the width of the sedimentation front. For short times, particle sedimentation speed has a linear dependence …


Cell Nuclei As Cytoplasmic Rheometers, Alison E. Patteson, J. M. Schwarz Feb 2021

Cell Nuclei As Cytoplasmic Rheometers, Alison E. Patteson, J. M. Schwarz

Physics - All Scholarship

Some researchers probe the mechanics of cells by perturbing them from the outside, such as using an atomic force microscope probe to record the amount of deformation of the cell in response to applying a prescribed force at a defined speed. Other researchers probe the mechanics of cells by perturbing them from the inside, an example of which is particle-tracking microrheology, in which the spontaneous motion of submicron, passive fluorescent beads ballistically injected earlier into the cell decodes the cell moduli. Both types of probes are typically composed of nonliving material. In this issue of Biophysical Journal, Moradi and …


A Tissue-Engineered Human Trabecular Meshwork Hydrogel For Advanced Glaucoma Disease Modeling, Haiyan Li, Tyler Bagué, Alexander Kirschner, Ana N. Strat, Haven Roberts, Robert W. Weisenthal, Alison E. Patteson, Nasim Annabi, W. Daniel Stamer, Preethi S. Ganapathy, Samuel Herberg Jan 2021

A Tissue-Engineered Human Trabecular Meshwork Hydrogel For Advanced Glaucoma Disease Modeling, Haiyan Li, Tyler Bagué, Alexander Kirschner, Ana N. Strat, Haven Roberts, Robert W. Weisenthal, Alison E. Patteson, Nasim Annabi, W. Daniel Stamer, Preethi S. Ganapathy, Samuel Herberg

Physics - All Scholarship

Abnormal human trabecular meshwork (HTM) cell function and extracellular matrix(ECM) remodeling contribute to HTM stiffening in primary open-angle glaucoma (POAG). Most current cellular HTM model systems do not sufficiently replicate the complex native three dimensional (3D) cell-ECM interface, limiting their use for investigating POAG pathology. Tissue-engineered hydrogels are ideally positioned to overcome shortcomings of current models. Here, we report a novel biomimetic HTM hydrogel and test its utility as a POAG disease model. HTM hydrogels were engineered by mixing normal donor-derived HTM cells with collagen type I, elastin-like polypeptide and hyaluronic acid, each containing photoactive functional groups, …