Densely ionizing (high-LET) galactic cosmic rays (GCR) contribute a significant component of the radiation risk in free space. Over a period of a few months-sufficient for the early stages of radiation carcinogenesis to occur-a significant proportion of cell nuclei will not be traversed. There is convincing evidence, at least in vitro, that irradiated cells can send out signals that can result ...

Even though bystander effects pertaining to radiation risk assessment has been extensively studied, the molecular players of radiation induced bystander effect (RIBE) in the context of cancer radiotherapy are poorly known. In this regard, the present study is aimed to investigate the effect of irradiated tumor cells on the bystander counterparts in mouse fibrosarcoma (WEHI 164 cells) tumor mode...

Bystander responses have been reported to be a major determinant of the response of cells to radiation exposure at low doses, including those of relevance to therapy. In this study, human glioblastoma T98G cell nuclei were individually irradiated with an exact number of helium ions using a single-cell microbeam. It was found that when only 1 cell in a population of approximately 1200 cells was ...

It has been recognized that bystander effect is one of the key factors for radiobiological effects, particularly in low-dose region. Although <1% of cell nuclei were actually traversed by an alpha particle, 30% of the cells showed an increased frequency of sister chromatid exchanges at very low dose (0.31 mGy) of alpha particles exposed to a CHO culture dish [1]. Since then, a number of studies...

Radiation therapy (RT) delivers tumour kill, directly and often via bystander mechanisms. Bladder toxicity is a dose limiting constraint in pelvic RT, manifested as radiation cystitis and urinary symptoms. We aimed to investigate the impact of radiation-induced bystander signaling on normal/cancer urothelial cells. Human urothelial cancer cells T24, HT1376 and normal urothelial cells HUC, SV-HU...

Introduction: Chondrosarcoma is second to osteogenic sarcoma in frequency as a malignant tumor of bone. It is difficult to obtain wide surgical resection margins because of its location adjacent to neurovascular and visceral structures. Neither irradiation nor chemotherapy seems to be an effective treatment for chondrosarcoma; thus new protocols are needed. We reported gene therapy of chondrosa...

A number of studies in the field of radiobiology contradict the Linear Non-Threshold model in the low dose range. These observations indicate that there may be more harmful effects for cells exposed to low dose irradiation than would be predicted by extrapolation from high dose data. For the last 20 years a new phenomenon in the area of the radiobiological effects has been described. A radiatio...

The efficacy of cancer gene therapy depends critically on "bystander effects" by which genetic modification of tumor cells results in killing of unmodified cells in the local microenvironment. In gene-dependent enzyme-prodrug therapy, expression of a prodrug-activating suicide gene is used to generate a cytotoxic metabolite that diffuses to nontransduced cells. The objective of this study was t...

All humans receive some radiation exposure and the risk for radiation-induced cancer at low doses is based on the assumption that there is a linear non-threshold relationship between dose and subsequent effect. Consequently, risk is extrapolated linearly from high radiation doses to very low doses. However, adaptive responses, bystander effects, and death-inducing effect may influence health ef...

Bystander effect is the communication of signals from irradiated to unexposed neighboring cells which is often mediated through factors released from irradiated cells. We have attempted to investigate whether UV-bystander phenomenon can modulate the sensitivity of A375 cells and its mechanism. For this purpose, the conditioned medium from UVC-irradiated cells, which contained these released fac...