1,721,016 research outputs found
GROWTH-KINETICS OF C3H10T1/2 CELLS EXPOSED TO LOW-LET RADIATION
No full textGrowth curves and size of the colonies of C3H10T1/2 cells exposed to low-LET radiation (31 MeV protons) were determined after 0, 1, 3, 5, and 7 Gy. The data show that: cell density at confluence was 3.3 x 10(4) cells/cm2; the initial division delay was very small; in the first 15 h the increase in the cell number was essentially the same at all doses; at 100 h the colony size distribution was very large, ranging from 0 to 7 generations, even within the control population. The temporal dependence of the growth properties of surviving and non-surviving cells was represented by the equation N = N0(Fe(a(t - dD] + (1 - F)ea/bD(1 - e - bD(1 - e - bD(t - dD]) where F is the surviving fraction, t the time of sampling, a the growth rate, d the division delay per unit dose, b the rate per unit of dose at which the non-surviving cells lose their ability to divide. The resulting values were: a = 0.029 +/- 0.002 h-1; b = 0.0041 +/- 0.0009 h-1 Gy-1 and d = 1 +/- 0.8 h Gy-1. It was found that growth curves are affected by non-surviving progeny up to 150, 200 and 250 h after irradiation at 3, 5 and 7 Gy, whereas at longer times the population consists essentially of progeny of surviving cells
Criteria and techniques for analysing cell survival data
No full textCell survival was studied by analyzing the inactivation probability density function and its fundamental parameters. Mean , varianceσ2 and modeDmode were evaluated and a set of equations relating these parameters to the usual parameters of the multitarget, multihit and linear-quadratic modelsDo andn, α andβ, k andλ are reported. The multihit equation used was an extension of the usual equation, to allow parameterk to assume values that are not necessarily integers. In the multitarget curve, the mode of inactivation probability density function, proved to be the quasi-threshold doseDq =Do ln(n). Relative variance, degree of asymmetry and degree of peakedness can be calculated from the shape parametersn in the multitarget model,k in the multihit model, and in the linear-quadratic model. From an analysis of eight published cell survival sets of data, on C3H10T1/2 cells exposed to low LET radiations, it was found that ,σ, andSF2 are the parameters which exhibit the least variation from experiment to experiment and the least variation in selecting the range of data available for estimation
Studio del danno al DNA indotto da radiazioni ionizzanti mediante simulazioni Montecarlo
No full textModelli interpretativi dell'inattivazione e della trasformazione di cellule irraggiate con radiazioni a basso ed alto LET
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Studio Radiobiologico del fascio di protoni da 65 MeV usato nella terapia dell'occhio presso il Centro Lacassagne di Nizza
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