Biomedical subjects

L T Lombardi

Publications and source records attributed to L T Lombardi.

4 recordsLinked to original sources

PubMed1987

Effects of split-dose irradiation on survival and oncogenic transformation induced by 31 MeV protons in C3H10T1/2 cells.

Survival and oncogenic transformation were studied in C3H10T1/2 cells exposed to 31 MeV protons. Total doses of 0.5, 1 and 7 Gy were delivered as single and two equal fractions with various time intervals up to 10 h between doses. With split doses as compared with single doses to a total dose of 7 Gy, survival increased by a factor of 2.5 +/- 0.2, whereas the frequency of transformation per surviving cell declined by a factor of 3.1 +/- 0.5. Maximal split-dose recovery occurred within the first 5 h for both endpoints. Further, the transformation frequency decreased by factors of 3.1 +/- 0.6 and 1.5 +/- 0.3 respectively for total doses of 0.5 and 1.0 Gy split into two equal fractions. The data for 1 and 7 Gy are compatible with data in the literature for other low LET radiations.

Animals↗

PubMed1985

In vitro cell transformations induced by 31 MeV protons.

Experimental data are presented on the frequencies of transformations in C3H10T1/2 cells exposed to 31 MeV protons (LET = 1.83 +/- 0.02 keV/mum in tissue) in a dose interval between 0.25 and 7.0 Gy. The transformation frequency per surviving cell curve showed a marked change in slope over the dose range used. At higher doses, above about 2 Gy, it steepened very sharply in comparison with the lower dose range. If fitted to a power of the dose, the power in the higher range was about five times that in the lower range.

Animals↗

PubMed1981

Energy deposition by proton beams of up to 31 MeV in microscopic volumes.

The frequency distributions of energy deposition in microscopic volumes for proton beams of various energies and energy spreads were determined by means of a "rossi type" proportional counter. Tissue equivalent spherical volumes of 0.6, 0.72, 0.80, 1.00, 1.25, 1.50, 1.75, 2.00 micrometer diameter were simulated. Frequency distributions of energy deposition per unit pathlength are reported and their behavior as a function of the simulated pathlength, beam energy and energy spread is discussed. The results indicate that energy deposition distributions in microscopic volumes for protons in the range 8-31 MeV are skewsymmetric distributions with a tail on the high energy side, and that degraded beams behave differently from monoenergetic ones. Dose mean lineal energy values have been quoted for beams used in radiobiological experiments.

Protons↗

PubMed1980

Multinucleate cells and micronucleus formation in cultured human cells exposed to 12 MeV protons and gamma-rays.

Cultured human cells of the EUE line were exposed to different doses of 12 MeV protons, plated and allowed to grow for 8 days; colonies were then scored for the presences of multinucleate cells and micronuclei. The frequency of both effects is an increasing function of the dose; the evaluated exponents of the dose-response equation (e = bDn) are n = 1.0 %/- 0.1 for multinucleate cells and n = 1.6 +/- 0.1 for micronuclei. By comparison with the results obtained with gamma irradiations, r.b.e. values were obtained for both effects. The correlation between the logarithm of the surviving fraction and the yield of the studied effects has been proved to be statiscally significant.

Cell Count↗