Free-radical Mechanisms in the Cytotoxic Action of Antitumour Antibiotics

Abstract

The purpose of this study was to choose an appropriate head scatter source model for the fast and accurate independent planar dose calculation for intensity-modulated radiation therapy (IMRT) with MLC. The performance of three different head scatter source models regarding their ability to model head scatter and facilitate planar dose calculation was evaluated. A three-source model, a two-source model and a single-source model were compared in this study. In the planar dose calculation algorithm, in-air fluence distribution was derived from each of the head scatter source models while considering the combination of Jaw and MLC opening. Fluence perturbations due to tongue-and-groove effect, rounded leaf end and leaf transmission were taken into account explicitly. The dose distribution was calculated by convolving the in-air fluence distribution with an experimentally determined pencil-beam kernel. The results were compared with measurements using a diode array and passing rates with 2%/2 mm and 3%/3 mm criteria were reported. It was found that the two-source model achieved the best agreement on head scatter factor calculation. The three-source model and single-source model underestimated head scatter factors for certain symmetric rectangular fields and asymmetric fields, but similar good agreement could be achieved when monitor back scatter effect was incorporated explicitly. All the three source models resulted in comparable average passing rates (>97%) when the 3%/3 mm criterion was selected. The calculation with the single-source model and two-source model was slightly faster than the three-source model due to their simplicity.

Cytotoxicity of a Novel Oil/Water Microemulsion System Loaded with Mitomycin‐C in In Vitro Lung Cancer Models

“…It requires activation by reductive enzymes under hypoxic conditions to produce its anticancer effects [Iyer and Szybalski, ; Bligh et al., ]. When activated, MMC forms cross‐links between neighboring guanine bases on the complementary deoxyribonucleic acid (DNA) strands [Tomasz et al., ], forms free radicals that contribute to the elimination of cancer cells [Emanuel et al., ], and induces apoptosis [Pirnia et al., ]. It is used as a single drug or in combination with other anticancer agents to treat colorectal and anal cancer, bladder cancer, cervix cancer, gastric cancer, lung cancer, pancreas cancer, etc.…”

Intracellular Distribution and Intracellular Dynamics of a Spin-Labeled Analogue of Doxorubicin by Fluorescence and EPR Spectroscopy

“…However, the generation of active oxygen species makes anthracyclin antibiotics highly cardiotoxic, which is a major complication of cancer chemotherapy. 2,3 Radical attack on cardiac muscle cells results in their death or degeneration. 4 A feasible approach to reducing cardiotoxicity would be to trap active radicals produced under the action of the drug.…”

Determination ofIn VivoBehavior of Mitomycin C-Loaded O/W Soybean Oil Microemulsion and Mitomycin C Solution Via Gamma Camera Imaging

“…6,7 When activated, MMC forms crosslinks between neighboring guanine bases on the complementary DNA strands. 8 It also forms free radicals that contribute to the elimination of cancer cells 9 and induces apoptotic pathways in the cells. 10 One of the main drawbacks of MMC in clinical application is its very short biological half-life, only approximately 50 minutes.…”