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L Tallone Lombardi

Publications and source records attributed to L Tallone Lombardi.

9 recordsLinked to original sources
PubMed1991

Criteria and techniques for analysing cell survival data.

Cell survival was studied by analyzing the inactivation probability density function and its fundamental parameters. Mean D, variance sigma 2 and mode Dmode were evaluated and a set of equations relating these parameters to the usual parameters of the multitarget, multihit and linear-quadratic models Do and n, alpha and beta, kappa and lambda are reported. The multihit equation used was an extension of the usual equation, to allow parameter kappa 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 dose Dq = Do ln(n). Relative variance, degree of asymmetry and degree of peakedness can be calculated from the shape parameters n in the multitarget model, kappa in the multihit model, and alpha/square root of beta 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 D, sigma, and SF2 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.

Analysis of Variance↗
PubMed1989

Growth kinetics of C3H10T1/2 cells exposed to low-LET radiation.

Growth 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.

Animals↗
PubMed1989

Cell density dependence of transformation frequencies in C3H10T1/2 cells exposed to X-rays.

The effects of cell density on transformation frequencies were studied in C3H10T1/2 cells exposed to 0.5 and 7 Gy of 200 kVp X-rays. Initial cell density strongly influenced transformation frequency; this decreased by a factor of between 4 and 10 when the initial seeding density was changed from 50 to 2500 cells/10 cm diameter Petri dish. The data were fitted with two equations: (a) an allometric function represented on a log-log scale by a straight line and (b) a sigmoidal function with plateaux between 50 and 250 cells/dish and above 600. The two curves are compared and their probabilities discussed. Our data indicate that the region between 50 and 250 cells/dish would be the most suitable region for dose-effect measurements. A study of the growth curves at 0.5 and 8.5 Gy shows that cell growth rates are not influenced by initial cell density.

Animals↗
PubMed1984

[Radiosensitivity and effect of dose fractionation in cultured cells].

Survival, division delay and repair of sublethal damage were studied as a function of the cellular age in cells of EUE line exposed to 31 MeV protons, (LET of 1.83 keV/micron in tissue). The findings are compared with data reported in the literature on various mammalian cell lines exposed to X and gamma rays, common behaviours are pointed out and the characteristics parameters quantified. Survival varies with cell age and reaches a maximum value at mid S and its minimum at late G1; the ratio between maximum and minimum ranges between 1.5 and 15 depending on the survival level. Division delay resulted to be equal to 6 and 12% of the generation time per Gy for mid G1 and mid-late S respectively. All the investigated lines are able to repair as much as 50% of the sublethal damage within one hour.

Cell Division↗
PubMed1981

Chromosome aberrations induced by protons up to 31 MeV in cultured human cells.

Chromosome aberrations were induced in cultured human cells by proton beams of 31, 12, and 8 MeV. The frequencies of isochromatid breaks and dicentrics have been analysed as a function of proton energy and dose. Both effects are largely dependent on proton energy; isochromatid breaks increased linearly with the dose, whereas dicentrics show a definite parabolic behaviour. The experimental data were fitted to the analytic form Y = KDn and Y = alpha D + beta D2 and the best fitted values of the parameters are reported and discussed. The values of RBE for the isochromatid breaks are in the ratio 1.7:1.3:1 for 8, 12, and 31 MeV respectively. In the case of the dicentrics the RBE values are dose-dependent function of the type CD-n. The three distributions of dicentrics among the cells do not fit a Poisson distribution.

Cell Line↗
PubMed1981

[Parameters of a cell population synchronized for radiosensitivity studies (author's transl)].

Human cultured cells (EUE) were synchronized by the method of the mitotic harvest and the degree of synchronization, during the first duplication interval, determined by various tests which include growth curves, mitotic index cell-size distributions. Values of synchronization index initially greater than 90% and desynchronization rate of about 2%/hour were evaluated. The survival after 1.75 Gy of 31 MeV protons irradiation shows a sensitive period in the late G1 followed by an increase in radioresistance to a maximum in S.

Cell Cycle↗