Biology subjects

Dunn, A.

Publications and source records attributed to Dunn, A..

22 records · Page 2Linked to original sources

bioRxiv2019

Women and Men Were Proportionally Represented Among Speakers at Major National Neurology Conferences in 2017

ObjectiveTo determine whether speaking roles at five major neurology conferences in 2017 show disproportionate representation by men. MethodsThis study consisted of two cross-sectional analyses. In the first part, we compared speaker characteristics across meetings and by gender using descriptive statistics. In the second part, we linked presenters to the American Medical Association (AMA) Masterfile. For the primary analysis in the second part using linked AMA speaker data, we built models to estimate the influence of gender on speaker roles. Results1493 speakers were identified and included in our cross-sectional analysis. Women made up 28% of presenters from the US and 18% of presenters from other countries. After adjusting for years from medical school graduation and subspecialty, no effect of gender on speaker activity was observed (odds ratio [OR] for women 0.91; 95% confidence interval [CI], 0.77-1.07). ConclusionsFactors aside from national conference speaking activity should be investigated to better understand sex differences in rank at top-ranked academic neurology programs.

neuroscience↗

bioRxiv2019

Loss of adipocyte identity through synergistic repression of PPARγ by TGF-β and mechanical stress

Adipocytes convert into myofibroblasts in a TGF-{beta}-dependent mouse model of fibrosis. The molecular steps and timing underlying this conversion are poorly understood, hindering development of antifibrotic therapies. Here we used two single-cell approaches, lineage tracing and live-cell imaging of an adipocyte marker PPAR{gamma}, to track the fate of adipocytes induced to convert by TGF-{beta}. We found that TGF-{beta} alone was not sufficient to activate the TGF-{beta} pathway and to induce myofibroblast conversion in cells with high PPAR{gamma} expression. However, robust conversion was observed when an additional PPAR{gamma}-inhibiting stimulus, mechanical stress applied by increasing adhesion area on a stiff matrix, was applied simultaneously with TGF-{beta}. We show that the PPAR{gamma} downregulation in response to increased adhesion area required both fibronectin and a sufficiently stiff extracellular matrix (ECM) and was partially mediated by Rho. Our results show for the first time the order of the molecular processes driving fat tissue fibrosis and the requirement for signal convergence for the loss of adipocyte identity.

cell biology↗

bioRxiv2018

Mechanobiological Conditioning of Mesenchymal Stem Cells Enhances Therapeutic Angiogenesis by Inducing a Hybrid Pericyte-Endothelial Phenotype

Stem cell therapies have great promise for revolutionizing treatments for cardiovascular disease and other disorders but have not yet achieved their potential due to poor efficacy and heterogeneity in patient response. Here, we used a novel high throughput screening system to optimize the conditioning of mesenchymal stem cells using a combinatorial set of biochemical factors, pharmacological inhibitors and biomechanical forces. Our studies revealed that a combination of specific kinase inhibitors and a complex mechanical strain waveform dramatically increased the population of mesenchymal stem cells that express markers for both pericytes and endothelial cells. These mechanically and pharmacologically conditioned mesenchymal stem cells had superior properties in enhancing endothelial tube formation, production of angiogenic growth factors and induction of angiogenesis following implantation. Overall, our work supports that combinatorial optimization of mechanical conditioning and pharmacological treatments can significantly enhance the regenerative properties of mesenchymal stem cells.

bioengineering↗

bioRxiv2018

Oscillatory cortical forces promote three dimensional cell intercalations that shape the mandibular arch

Multiple vertebrate embryonic structures such as organ primordia are composed of a volume of confluent cells. Although mechanisms that shape tissue sheets are increasingly understood, those which shape a volume of cells remain obscure. Here we show 3D mesenchymal cell intercalations, rather than cell divisions and biophysical tissue properties, are essential to shape the mandibular arch of the mouse embryo. Using a genetically encoded vinculin tension sensor, we show that cortical force oscillations promote these intercalations. Genetic loss and gain of function approaches show that Wnt5a functions as a spatial cue to coordinate cell polarity with cytoskeletal oscillation. YAP/TAZ and PIEZO1 serve as downstream effectors of Wnt5a-mediated actomyosin bias and cytosolic calcium transients, respectively, to ensure appropriate tissue form during growth. Our data support oriented 3D cell neighbour exchange as a conserved mechanism driving volumetric morphogenesis.

developmental biology↗