ABSTRACT
Electrotaxis is the cell migration in the presence of an electric field (EF). This migration is parallel to the EF vector and overrides chemical migration cues. In this paper we introduce a mathematical model for the electrotaxis in osteoblastic cells. The model is evaluated using different EF strengths and different configurations of both electrical and chemical stimuli. Accordingly, we found that the cell migration speed is described as the combination of an electrical and a chemical term. Cell migration is faster when both stimuli orient cell migration towards the same direction. In contrast, a reduced speed is obtained when the EF vector is opposed to the direction of the chemical stimulus. Numerical relations were obtained to quantify the cell migration speed at each configuration. Additional calculations for the cell colonization of a substrate also show mediation of the EF strength. Therefore, the term electro-osteoconduction is introduced to account the electrically induced cell colonization. Since numerical results compare favorably with experimental evidence, the model is suitable to be extended to other types of cells, and to numerically explore the influence of EF during wound healing.
Subject(s)
Cell Movement , Electricity , Models, Biological , Osteoblasts/cytology , ChemotaxisABSTRACT
In this study we evaluated for a realistic head model the 3D temperature rise induced by a mobile phone. This was done numerically with the consecutive use of an FDTD model to predict the absorbed electromagnetic power distribution, and a thermal model describing bioheat transfer both by conduction and by blood flow. We calculated a maximum rise in brain temperature of 0.11 degrees C for an antenna with an average emitted power of 0.25 W, the maximum value in common mobile phones, and indefinite exposure. Maximum temperature rise is at the skin. The power distributions were characterized by a maximum averaged SAR over an arbitrarily shaped 10 g volume of approximately 1.6 W kg(-1). Although these power distributions are not in compliance with all proposed safety standards, temperature rises are far too small to have lasting effects. We verified our simulations by measuring the skin temperature rise experimentally. Our simulation method can be instrumental in further development of safety standards.
Subject(s)
Body Temperature/radiation effects , Brain/radiation effects , Computer Simulation , Electromagnetic Fields , Models, Biological , Telephone , Cerebrovascular Circulation/radiation effects , Humans , Magnetic Resonance Imaging , Scalp/anatomy & histology , Skin Temperature/radiation effectsABSTRACT
The electromagnetic heat dissipation in a radially layered biological tissue inside a circular cylinder has been investigated theoretically. The theory is based on a three-dimensional model and the electromagnetic field is assumed to be generated by a prescribed electric field along a ring-shaped aperture. The method of computation employs the spatial Fourier transform of all field quantities with respect to the axial coordinate, after which the field equations are solved in the spectral domain. Subsequently, an inverse Fourier transform is carried out to compute the quantities that are of interest to the clinical deep-body hyperthermia system at hand. For a number of representative configurations numerical results at 70 MHz are given.
