Ayelet Walter

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OBJECTIVES The luminal surface of the gut is lined with a monolayer of epithelial cells that acts as a nutrient absorptive engine and protective barrier. To maintain its integrity and functionality, the epithelium is renewed every few days. Theoretical models are powerful tools that can be used to test hypotheses concerning the regulation of this renewal(More)
In this paper, we review multi-scale models of solid tumour growth and discuss a middle-out framework that tracks individual cells. By focusing on the cellular dynamics of a healthy colorectal crypt and its invasion by mutant, cancerous cells, we compare a cell-centre, a cell-vertex and a continuum model of cell proliferation and movement. All models(More)
A computational study of discrete 'cell-centre' approaches to modelling the evolution of a collection of cells is undertaken. The study focuses on the mechanical aspects of the tissue, in order to separate the passive mechanical response of the model from active effects such as cell-growth and cell division. Issues which arise when implementing these models(More)
The dissolution and formation of egg phosphatidylcholine (PC) vesicles by the detergent octyl glucoside were examined systematically by using resonance energy transfer between fluorescent lipid probes, turbidity, and gel filtration chromatography. Resonance energy transfer was exquisitely sensitive to the intermolecular distance when the lipids were in the(More)
Fusion of vesicular stomatitis virus (VSV) with Vero cells was measured after exposure of the virus to low pH under a variety of experimental conditions. The method of relief of fluorescence self-quenching of the probe octadecylrhodamine was used to monitor fusion. Incubation of the virus at pH 5.5 prior to binding to cells led to significant enhancement of(More)
We have studied fusion between membranes of vesicular stomatitis virus (VSV) and Vero cells using an assay for lipid mixing based on the relief of self-quenching of octadecylrhodamine (R18) fluorescence. We could identify the two pathways of fusion by the kinetics of R18 dequenching, effects of inhibitors, temperature dependence, and dependence on osmotic(More)
Polylysine induced aggregation and fusion of negatively charged small unilamellar phosphatidylcholine vesicles containing at least 10% anionic lipid. Aggregation was followed by absorbance changes and fusion was assayed both by electron microscopy and by fluorescence energy transfer between lipid probes. A method for preparing asymmetric vesicles, where the(More)
The composition of mixed micelles of egg phosphatidylcholine (PC) and octyl glucoside was studied by a novel technique based on measuring resonance energy-transfer efficiency between two fluorescent lipid probes present in trace amounts. Equations were derived for calculating the stoichiometry of the composition of mixed micelles from the energy-transfer(More)
We have investigated the binding ability to DNA of compounds belonging to the 2-azaanthraquinone-type structure and have examined the effect on the activity of DNA gyrase as well as on mammalian topoisomerases in vitro. Using different biophysical techniques it was found that one of these ligands, 9-((2-dimethylamino)ethyl)amino)-6-hydroxy-7-methoxy-5,(More)
The ability of an HPLC gel exclusion column (TSK G6000PW) to separate lipid vesicles, viruses, and biological vesicles according to size was tested and compared with separations on Sephacryl S1000. The columns were calibrated using vesicular Stokes radii determined by quasielastic light scattering. The vesicles separated according to size on both types of(More)