Biology subjects

Goswami, R.

Publications and source records attributed to Goswami, R..

4 recordsLinked to original sources

bioRxiv2018

Polyacrylamide Bead Sensors for in vivo Quantification of Cell-Scale Stress in Zebrafish Development

Mechanical stress exerted and experienced by cells during tissue morphogenesis and organ formation plays an important role in embryonic development. While techniques to quantify mechanical stresses in vitro are available, few methods exist for studying stresses in living organisms. Here, we describe and characterize cell-like polyacrylamide (PAAm) bead sensors with well-defined elastic properties and size for in vivo quantification of cell-scale stresses. The beads were injected into developing zebrafish embryos and their deformations were computationally analyzed to delineate spatio-temporal local acting stresses. With this computational analysis-based cell-scale stress sensing (COMPAX) we are able to detect pulsatile pressure propagation in the developing neural rod potentially originating from polarized midline cell divisions and continuous tissue flow. COMPAX is expected to provide novel spatiotemporal insight into developmental processes at the local tissue level and to facilitate quantitative investigation and a better understanding of morphogenetic processes.

biophysics↗

bioRxiv2018

Standardized microgel beads as elastic cell mechanical probes

Cell mechanical measurements are gaining increasing interest in biological and biomedical studies. However, there are no standardized calibration particles available that permit the cross-comparison of different measurement techniques operating at different stresses and time-scales. Here we present the rational design, production, and comprehensive characterization of poly-acylamide (PAAm) microgel beads mimicking biological cells. We produced mono-disperse beads at rates of 20 - 60 kHz by means of a microfluidic droplet generator, where the pre-gel composition was adjusted to tune the beads elasticity in the range of cell and tissue relevant mechanical properties. We verified bead homogeneity by optical diffraction tomography and Brillouin microscopy. Consistent elastic behavior of microgel beads at different shear rates was confirmed by AFM-enabled nanoindentation and real-time deformability cytometry (RT-DC). The remaining inherent variability in elastic modulus was rationalized using polymer theory and effectively reduced by sorting based on forward-scattering using conventional flow cytometry. Our results show that PAAm microgel beads can be standardized as mechanical probes, to serve not only for validation and calibration of cell mechanical measurements, but also as cell-scale stress sensors.\n\nSignificance StatementOften vastly different cell mechanical properties are reported even for the same cell type when employing different measurement techniques. This discrepancy shows the urgent need for standardized calibration particles to cross-compare and validate techniques. Microgel beads can serve this purpose, but they have to fulfil specific requirements such as homogeneity, sizes and elasticities in the range of the cells, and they have to provide comparable results independent of the method applied. Here we demonstrate the standardized production of polyacrylamide microgel beads with all the features an elastic cell-mimic should have. These can not only be used as method calibration particles, but can also serve as cell-scale sensors to quantify normal and shear stresses exerted by other cells and inside tissues, enabling many new applications.

biophysics↗

bioRxiv2018

The relationship between brain atrophy and cognitive-behavioral symptoms in retired Canadian football players with multiple concussions

Multiple concussions, particularly in contact sports, have been associated with cognitive deficits, psychiatric impairment and neurodegenerative diseases like chronic traumatic encephalopathy. We used volumetric and deformation-based morphometric analyses to test the hypothesis that repeated concussions may be associated with smaller regional brain volumes, poorer cognitive performance and behavioural symptoms among former professional football players compared to healthy controls. This study included fifty-three retired Canadian Football League players, 25 age- and education-matched healthy controls, and controls from the Cambridge Centre for Aging and Neuroscience database for validation. Volumetric analyses revealed greater hippocampal atrophy than expected for age in former athletes with multiple concussions than controls and smaller left hippocampal volume was associated with poorer verbal memory performance. Deformation-based morphometric confirmed smaller bilateral hippocampal volume that were associated with poorer verbal memory performance in athletes. Repeated concussions may lead to greater regional atrophy than expected for age.

neuroscience↗

bioRxiv2017

Polyclonal HIV envelope-specific breast milk antibodies limit founder SHIV acquisition and cell-associated virus loads in infant rhesus monkeys.

Vertical HIV-1 transmission via breastfeeding is the predominant contributor to pediatric infections that are ongoing in this era of highly effective antiretroviral therapy (ART). Remarkably, only ~10% of infants chronically exposed to the virus via breastfeeding from untreated HIV-infected mothers become infected, suggesting the presence of naturally protective factors in breast milk. HIV-specific maternal antibodies are obvious candidates as potential contributors to this protection. This study assessed the protective capacity of common HIV envelope-specific non-broadly neutralizing antibodies isolated from breast milk of HIV-infected women in an infant rhesus monkey (RM), tier 2 SHIV oral challenge model. Prior to oral SHIV challenge, infant RMs were i.v. infused with either a single weakly-neutralizing monoclonal antibody (mAb), a tri-mAb cocktail with neutralizing and ADCC functionalities, or an anti-influenza HA control mAb. Of these groups, the fewest tri-mAb-treated infants developed plasma viremia (2/6, 3/6, and 6/8 animals viremic in tri-mAb, single-mAb, and control mAb groups, respectively). Tri-mAb-treated infants demonstrated significantly fewer transmitted/founder SHIV variants in plasma and decreased peripheral CD4+ T cell proviral loads at 8 week post-challenge compared to control mAb-treated infants. Abortive infection was observed as detectable CD4+ T cell provirus in non-viremic control mAb- and single-mAb-, but not tri-mAb-treated animals. Taken together, these results support the potential viability of maternal or infant vaccine strategies that elicit non-broadly neutralizing antibodies to prevent vertical transmission of HIV through breastfeeding.

immunology↗