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l-Glutamic Acid): Efficient Carrier of Cancer Therapeutics and Diagnostics
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Guodong Zhang, Edward F. Jackson, Sidney Wallace, Chun Li
Combining chemotherapy and radiotherapy has significantly improved response and survival rates in patients with many solid tumors. Many chemotherapeutic agents can increase the radiosensitivity of tumors, potentiating the tumor response to radiation-caused damage. It was hypothesized that combining radiotherapy and chemotherapy using a polymer–drug conjugate may lead to a stronger radiosensitizing effect than using the drug alone. Irradiation can, in turn, potentiate the tumor response to polymer–drug conjugates by increasing tumor vascular permeability and the uptake of these conjugates into solid tumors. To test this hypothesis, PG–TXL was used as a model polymer–drug conjugate.58 Administration of PG–TXL delayed the growth of OCa-1 syngeneic murine ovarian tumors in C3Hf/Kam mice. However, when PG–TXL was given in combination with tumor irradiation, significantly enhanced anti-tumor activity was observed. Using tumor growth delay as an end point, enhancement factors ranging from 1.36 to 4.4 were observed; these values depended on the doses of PG–TXL and radiation delivered. It was found that complete tumor regression occurred with the use of increased radiation doses (> 10 Gy) and PG–TXL doses (> 80 mg/kg equivalent TXL).59 Similar results were observed in a mammary MCa-4 carcinoma model.60 In contrast, it was found that combined radiotherapy and TXL treatment yielded an enhancement factor of less than 1.0 in MCa-4 tumors, indicating that conjugation of TXL with PG is necessary to improve that radiosensitization effect of TXL. When the treatment end point was tumor cure, enhancement factors as high as 8.4 and 7.2 were observed after fractionated and singledose radiotherapy, respectively.61,62
Physical study of proton therapy at CANAM laboratory on medulloblastoma cell lines DAOY
Published in Radiation Effects and Defects in Solids, 2020
L. Torrisi, M. Davidkova, V. Havranek, M. Cutroneo, A. Torrisi
The biological effectiveness of radiation depends on the linear energy transfer (LET), total absorbed dose, dose-rate, number of fractions and radio-sensitivity of the targeted cells or tissues. Radiation can either directly or indirectly, by the accelerated electrons produced photons and consequent radical formation, damages the genome of the cell. Low LET radiations (X-rays, gamma rays and beta particles) deposit a relatively small quantity of energy. Energetic particles, such as protons and other charged ions or neutrons, may deposit more energy on the targeted and cause more biological effects than the low LET radiations. The major effects of ionizing radiation on tissues are the direct cell killing mostly by damaging the DNA, resulting in the depopulation of cell number and subsequent functional deficiency. The ionizing radiation applied in the cancer treatment induces a complex response in the cells; some processes aim to repair the radiation-induced damage of the normal cells, whereas others induce cancer cell death.
Gold nanoparticles as radiosensitizer for radiotherapy and diagnosis of COVID-19: A review
Published in Nanoscale and Microscale Thermophysical Engineering, 2022
Abdul Khaliq Mokhtar, Norsyahidah Mohd Hidzir, Faizal Mohamed, Irman Abdul Rahman, Syazwani Mohd Fadzil, Afifah Mardhiah Mohamed Radzi, Nur Ain Mohd Radzali
It is difficult to use radiotherapy alone to kill all cancer cells and tumors and simultaneously reduce healthy cells’ mortality. One way to increase its efficacy is by introducing a radiosensitizer, that is, molecules capable of improving the radiosensitivity of tumor cells. Radiosensitizers are pharmacological or chemical agents that increase ionizing radiation cytotoxicity [18]. Radiosensitizers also could be defined as any compounds that can achieve greater tumor inactivation than the additive effect each modality would have as predicted when combined with radiation. The use of chemical agents that simply have an additive effect in normal tissues is similar to an increase in the dose of radiation without any differential benefits [19].