ABSTRACT
To describe low-frequency dynamics of DNA macromolecules a model is developed taking into account the hydrogen bond stretching in base pairs, the backbone flexibility and intranucleoside mobility. For double-stranded DNA the normal vibrations are found and the structure of low-frequency spectrum is determined. The agreement between theory and Raman spectroscopy data for B-DNA is demonstrated. Conformational dependences of vibration spectrum during the B----A and helix----coil DNA transitions are studied. The contribution coming from low-frequency mobility to the nucleic-protein recognition processes is discussed.
Subject(s)
DNA/chemistry , Hydrogen Bonding , Macromolecular Substances , Mathematics , Models, Chemical , Nucleic Acid Conformation , Spectrum Analysis, Raman , Thermodynamics , VibrationABSTRACT
Dynamics of interphase peripheral blood lymphocyte death is studied in terms of a general model based on a random damage distribution among cells and stochastic time of their death. Some particular cases of this model are analysed. Possible causes of shaping "biphase" dose-dependence curves for lymphoid cell survival after irradiation are discussed.
Subject(s)
Interphase/radiation effects , Lymphocytes/radiation effects , Models, Biological , Animals , Cell Survival/radiation effects , Dose-Response Relationship, Radiation , Humans , Lymphocytes/cytology , Stochastic ProcessesABSTRACT
A phenomenological scheme is proposed to describe dose- and time-dependences of the interphase cell death in terms of a continual model of radiation injury. Different regularities of the postirradiation recovery of cells are discussed. The results obtained are in agreement with the experimental data.
Subject(s)
Cell Survival/radiation effects , Interphase/radiation effects , Mathematics , Models, BiologicalABSTRACT
A conformational mobility model is proposed to describe the low-frequency DNA structure dynamics. The transverse oscillations of structure elements in a double-stranded chain are studied. The frequency of DNA long-wave conformational oscillations are estimated and the theory is shown to agree with experiment. DNA low-frequency Raman spectra are interpreted.
Subject(s)
DNA , Nucleic Acid Conformation , Models, Molecular , Models, TheoreticalABSTRACT
The authors propose a biophysical justification of a radiation-induced injury and interphase death of cells. The injury to certain units of the microtrabecular network and cytoskeleton is considered to be a primary biological effect of radiation on cells. The role of these structural changes in the development of the specific radiation response is discussed. It is found possible to describe formally, by the defined parameters of the proposed model, the survival curves for not only interphase but also reproductive cell death.
Subject(s)
Cell Survival/radiation effects , Interphase/radiation effects , Models, Biological , Animals , Biophysical Phenomena , Biophysics , Humans , MathematicsABSTRACT
A model of radiation injury of cells is proposed. It involves a diffusion description of the distribution of elementary lesions among cells during irradiation. It is assumed that the probability of cell death depends on the number of elementary lesions. This probability is described by the model of nonspecific radiation response of cells. The survival function is found for a particular case of the dependence of cell death probability on the number of elementary lesions. The asymptotes of this function are obtained for low and high radiation doses. A qualitative comparison with the experimental data is presented.
Subject(s)
Cell Survival/radiation effects , Interphase/radiation effects , Animals , Humans , Mathematics , Models, BiologicalABSTRACT
A model for consistent oxygen and glucose uptake by tumor cells is suggested. Oxygen uptake is considered to depend, under certain conditions, on that of glucose. Equations for calculation of oxygen and glucose distributions in cell spheroids are given (models of solid tumor in vitro).
