07.01.2014 Views

LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

CHAPTER 3<br />

RESULTS<br />

3.3.2 Oxygen beam induced signaling in mammalian cells and its comparison with Gamma<br />

irradiation.<br />

Having established the signaling differences between carbon beam and gamma irradiation in<br />

A549 cells, the variance in signaling pattern with oxygen beam was studied. Oxygen beams are<br />

high linear energy transfer (LET) radiation characterized by higher relative biological<br />

effectiveness than low LET radiation. The aim of the current study was to determine the<br />

signaling differences between γ- and oxygen ion-irradiation. Activation of various signaling<br />

molecules was looked in A549 lung adenocarcinoma cells irradiated with 2Gy oxygen, 2Gy or<br />

6Gy γ-radiation.<br />

3.3.2.1. Cytotoxicity of oxygen ions Vs gamma<br />

To determine the sensitivity of cells to similar dose of high and low LET radiation, their ability<br />

to form colonies after irradiation was observed. Irradiation of exponentially growing A549 cells<br />

with equal doses of gamma and oxygen beam (614 keV/ µm) revealed that at same dose oxygen<br />

ions were much more cytotoxic than gamma rays as assessed by the clonogenic cell survival<br />

assay. The calculated RBE (relative biological effectiveness) for A549 cells irradiated with 1Gy<br />

oxygen ions particles relative to γ rays was found to be nearly 3 at 20% survival (Fig. 3.3.2.1).<br />

The calculated D 0 value from the plot curve for A549 cells was found to be 0.6Gy for oxygen<br />

ions and 2.5Gy for γ rays.<br />

157

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!