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Abstract

We consider a scheme of aging with two possible mechanisms of senescence processes: aging with apoptosis and necrosis for differentiated cells and a multistage process of malignant transformation. Our model describes the multistage phenomena of aging and carcinogenesis by a set of stochastic equations using multivariate and diffusion processes. This model fits experimental data on the acceleration of aging processes from postnatal exposure to 5-bromodeoxyuridine (BrdU), and the induction of genome instability. The methods of stochastic modeling and computer simulation of the processes of aging and carcinogenesis have been used for the verification of the biological suggestions.

Relationships between cancer and aging: a multilevel approach

“…Both pathways comprise multi-stage processes, many steps of which are wellcharacterized in relation to the process of development, maintenance and carcinogenesis (Anisimov 1983(Anisimov , 2003aMoolgavkar et al 1999;Hahn and Weinberg 2002;Weinberg 2008). However, the multi-stage pattern of aging needs serious studies and formalization (Butov et al 2002;Anisimov 2000c). It is worthy of note that multistage models of cellular aging and immortalization have been developed in an attempt to explain delayed genomic instability, in which initiation of carcinogenesis is linked not only to a direct increase in chromosomal aberrations and mutations of oncogenes and tumor suppressor genes, but also to enhanced levels of aberrations and mutations in distant progeny and a predisposition to immortalization (Butov et al 2002).…”

“…However, the multi-stage pattern of aging needs serious studies and formalization (Butov et al 2002;Anisimov 2000c). It is worthy of note that multistage models of cellular aging and immortalization have been developed in an attempt to explain delayed genomic instability, in which initiation of carcinogenesis is linked not only to a direct increase in chromosomal aberrations and mutations of oncogenes and tumor suppressor genes, but also to enhanced levels of aberrations and mutations in distant progeny and a predisposition to immortalization (Butov et al 2002). Carcinogenesis is a multistage process: neoplastic transformation implies the engagement of a cell through sequential stages, and different agents may affect the transition between contiguous stages in different ways (Berenblum 1975;Hahn and Weinberg 2002;Weinberg 2008;Hu and Polyak 2008).…”

“…Mathematical modeling of processes of aging and carcinogenesis in tissues based on the experimental data alluded to above (Napalkov et al 1989;Anisimov and Osipova 1992;Anisimov 1994Anisimov , 1995 has been performed (Butov et al 2002) on the basis of the recurrent algorithms constructed on the stochastic equations in terms of semi-Martingale characteristics of these processes. The results support the conclusion that BrdUrd treatment causes accelerated aging in tissues with proliferating cells, as well as a mortality increment directly due to tumorigenesis.…”

Conditions and possible mechanism of condensation of e–h pairs in bulk GaAs at room temperature

“…In case of low temperatures and densities, such bound states are referred to as excitons. Bose condensation of excitons has been previously observed at cryogenic temperatures in some semiconductors, for example, in Cu 2 O and quantum-well GaAs/AlGaAs heterostructures [2][3][4][5].…”

“…(2) gives E p = 1.1 pJ. This value is by [3][4] times larger under lasing conditions when the emission line is typically shifted by about kT up inside the band from the edge [8]. A spectral hole must appear in the carrier distribution when the electrons and holes recombine simultaneously (see Fig.…”