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Publications Cell Physics Division

Please also find a cross-linked version of this list at Google Scholar.

2013

Mechanics Meets Medicine

Jochen Guck, Edwin R. Chilvers

SCIENCE TRANSLATIONAL MEDICINE 5 (212) 212fs41 (2013) | Journal

Mechanics in Neuronal Development and Repair

Kristian Franze, Paul A. Janmey, Jochen Guck

Annual Review of Biomedical Engineering 15 (1) 227-251 (2013) | Journal

Biological cells are well known to respond to a multitude of chemical signals. In the nervous system, chemical signaling has been shown to be crucially involved in development, normal functioning, and disorders of neurons and glial cells. However, there are an increasing number of studies showing that these cells also respond to mechanical cues. Here, we summarize current knowledge about the mechanical properties of nervous tissue and its building blocks, review recent progress in methodology and understanding of cellular mechanosensitivity in the nervous system, and provide an outlook on the implications of neuromechanics for future developments in biomedical engineering to aid overcoming some of the most devastating and currently incurable CNS pathologies such as spinal cord injuries and multiple sclerosis.

Elastic theory for the deformation of a solid or layered spheroid under axisymmetric loading

Lars Boyde, Andrew Ekpenyong, Graeme Whyte, Jochen Guck

ACTA MECHANICA 224 (4) 819-839 (2013) | Journal

The theory for the deformations of a spheroidal particle is of great scientific interest in numerous physical and biological problems ranging from fracture analysis of plain solids to the compression of biological cells in an atomic force microscope or during micropipette aspiration. Using a formulation in terms of Papkovich-Neuber potentials, we derive the deformations of a prolate, elastic spheroid under known axisymmetric loading. The internal stresses to which the object is subjected are deduced from Hooke's law of elasticity in prolate spheroidal coordinates. The generalisation to layered spheroids with viscoelastic properties is also discussed. Since for isotropic objects the surface displacements and stresses are directly related by the elastic modulus and Poisson's ratio alone, the presented, closed-form, analytical solutions may be applied to deduce these important elastic constants from standard stress-deformation experiments. We illustrate the versatility of the findings by analysing the surface displacements and stress states of spheroids with small and large aspect ratios in the presence of both normal and shear surface tractions. Of particular interest in this study is the influence of Poisson's ratio on the deformation of a near-spherical particle, for instance a soft cancer cell, which is subjected to surface stresses of the kind that can be found in optical traps, like the optical stretcher.

Bacterial infection of macrophages induces decrease in refractive index

Andrew E. Ekpenyong, Si Ming Man, Sarra Achouri, Clare E. Bryant, Jochen Guck, Kevin J. Chalut

JOURNAL OF BIOPHOTONICS 6 (5) 393-397 (2013) | Journal

Infection of cells by pathogens leads to both biochemical and structural modifications of the host cell. To study the structural modifications in a label-free manner, we use digital holographic microscopy, DHM, to obtain the integral refractive index distribution of cells. Primary murine bone marrow derived macrophages (BMDM) infected with Salmonella enterica serovar Typhimurium, undergo highly significant reduction in refractive index, RI, compared to uninfected cells. Infected BMDM cells from genetically modified mice lacking an inflammatory protein that causes cell death, caspase 1, also exhibit similar decrease in RI. These data suggest that any reduction in RI of Salmonella -infected BMDMs is pathogen induced and independent of caspase 1-induced inflammation or cell death. This finding suggests DHM may be useful for general real time monitoring of host cell interactions with infectious pathogens. ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Contact

Cell Physics Division
Prof. Vahid Sandoghdar
Acting Division Head

Max Planck Institute for the Science of Light
Staudtstr. 2
91058 Erlangen, Germany

guck-office@mpl.mpg.de

+49 9131 8284 501

Principal Investigator

Max-Planck-Zentrum für Physik und Medizin
Kussmaulallee 2
91054 Erlangen, Germany

MPL Research Centers and Schools

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