Purpose: Cell adhesion to extracellular matrix (ECM) proteins is mediated by the integrin family and has been known to modify radiation sensitivity and resistance in several cell types, including ...cancer cells. In particular, β1 integrin signaling has been implicated in the progression and metastasis of various cancers and has been shown to facilitate resistance to radiation therapy.
Conclusion: In this mini-review, we provide a brief overview of integrin targeting in radiation therapy. We specifically focus on the updated findings of β1 integrin-mediated signaling pathways after exposure to ionising radiation (IR) using in vitro and in vivo experimental models, which could represent promising therapeutic targets for breast cancer.
When managed with appropriate radiation protection procedures, ionising radiation is of great benefit to society. Opacification of the lens, and vision impairing cataract, have recently been ...recognised at potential effects of relatively low dose radiation exposure, on the order of 1 Gy or below. Within the last 10 years, understanding of the effects of low dose ionising radiation on the lens has increased, particularly in terms of DNA damage and responses, and how multiple radiation or other events in the lens might contribute to the overall risk of cataract. However, gaps remain, not least in the understanding of how radiation interacts with other risk factors such as aging, as well as the relative radiosensitivity of the lens compared to tissues of the body. This paper reviews the current literature in the field of low dose radiation cataract, with a particular focus on sensitivity and latency.
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•Lens sensitivity to radiation exposure.•Confounding factors of radiation-induced cataract.•Current understanding of mechanisms.
The response of radiochromic film, GafChromic
™
EBT, was investigated for dependence on x-ray beam energy using a previously reported real-time optical readout approach. X-ray beams of energy from
75
...kVp
to
18
MV
were employed. The dose-induced change in optical density for the EBT film was compared to values obtained for GafChromic
™
HS and MD-55 films, exposed under the same conditions. All responses were normalized to that obtained for
Co
60
irradiation. While change in optical density for
1
Gy
of applied dose as measured with HS and MD-55 films decreased by approximately 40% at low energies, the mean change in optical density of EBT film remained within 3% of that in the
Co
60
beam over the entire energy range.
Beginning in the 1990s, and emphasized in 2000 with the release of an Institute of Medicine report, healthcare providers and institutions have dedicated time and resources to reducing errors that ...impact the safety and well-being of patients. But in January 2010 the first of a series of articles appeared in the
New York Times
that described errors in radiation oncology that grievously impacted patients. In response, the American Association of Physicists in Medicine and the American Society of Radiation Oncology sponsored a working meeting entitled "Safety in Radiation Therapy: A Call to Action." The meeting attracted 400 attendees, including medical physicists, radiation oncologists, medical dosimetrists, radiation therapists, hospital administrators, regulators, and representatives of equipment manufacturers. The meeting was cohosted by 14 organizations in the United States and Canada. The meeting yielded 20 recommendations that provide a pathway to reducing errors and improving patient safety in radiation therapy facilities everywhere.
Purpose: To investigate radiation-induced bystander responses and to determine the role of gap junction intercellular communication and the radiation environment in propagating this response.
...Materials and methods: We used medium transfer and targeted irradiation to examine radiation-induced bystander effects in primary human fibroblast (AG01522) and human colon carcinoma (RKO36) cells. We examined the effect of variables such as gap junction intercellular communication, linear energy transfer (LET), and the role of the radiation environment in non-targeted responses. Endpoints included clonogenic survival, micronucleus formation and foci formation at histone 2AX over doses ranging from 10-100 cGy.
Results: The results showed no evidence of a low-LET radiation-induced bystander response for the endpoints of clonogenic survival and induction of DNA damage. Nor did we see evidence of a high-LET, Fe ion radiation (1 GeV/n) induced bystander effect. However, direct comparison for 3.2 MeV α-particle exposures showed a statistically significant medium transfer bystander effect for this high-LET radiation.
Conclusions: From our results, it is evident that there are many confounding factors influencing bystander responses as reported in the literature. Our observations reflect the inherent variability in biological systems and the difficulties in extrapolating from in vitro models to radiation risks in humans.
This work is a follow-up study for a recently-proposed 3D radiochromic gel dosimeter that contains a tetrazolium salt and a physical gel matrix made of poly(ethylene oxide)-block-poly(propylene ...oxide)-block-poly(ethylene oxide) (Pluronic F-127). Several tetrazolium salts were examined in this work, including tetrazolium violet, blue tetrazolium chloride, nitro blue tetrazolium chloride (NBT), tetranitro blue tetrazolium chloride (tNBT) and thiazolyl blue tetrazolium bromide (TBTB). The salt-containing gel dosimeters were compared with the first Pluronic gel composition that contained 2,3,5-triphenyltetrazolium chloride (TTC) as the radiation-sensitive component (dose sensitivity of 0.0023 (Gy cm)
). The Pluronic gels with NBT and tNBT outperformed the other gels, including the TTC-containing gel, with respect to their dose sensitivity and low dose-response. The NBT gels were found to have better stability over time than tNBT gels. Sensitization of the gels to ionizing radiation was examined by addition of tert-butyl alcohol and sodium formate. The best composition was 0.0818% NBT (1 mM), 25% Pluronic F-127 and 0.136 × 10
% sodium formate. This gel dosimeter was insensitive to changes in dose rate for photons of different energies. The mean dose sensitivity amounted to 0.0047 ± 0.1 × 10
(Gy cm)
. A diversion in the dose-response was observed for the gel irradiated with electrons. Additional characteristics of the NBT gel were a linear-dose range and a dynamic-dose range between <1 and ⩾150 Gy and a dose threshold of <1 Gy. The dose distribution registered for the NBT-Pluronic gel was stable after irradiation for over 7 d with no visible diffusion of the irradiated part, which is analogous to the original TTC-Pluronic gel.
People are more often exposed to low as opposed to high doses of ionising radiation (IR). Knowledge on the health risks associated with exposures to ionising radiation above 100 mGy is quite well ...established, while lower dose risks are inferred from higher level exposure information (ICRP). The health risk assessments are mainly based on epidemiological data derived from the atomic bombing of Hiroshima and Nagasaki, medical exposure studies and follow-up studies after nuclear accidents. For the estimation of long-term stochastic radiation health effects (such as cancer) and radiation protection purposes, a linear non-threshold (LNT) model is applied. However, the general validity of the LNT hypothesis for extrapolations from effects of high to low doses (<100 mGy) and low dose-rates (<6 mGy/h) has been questioned as epidemiological studies are statistically limited at low doses and unable to evaluate low dose and low dose-rate health risks (UNSCEAR). Thus, uncertainties on health risks need to be clarified with the help of mechanistic studies. The European Network of Excellence DoReMi (2010-2016) was designed to address some of the existing uncertainties and to identify research lines that are likely to be most informative for low dose risk assessment. The present review reports the results obtained from studies addressing the induction of cancer and non-cancer effects by low dose IR as well as on individual radiation sensitivity. It is shown that low dose and low dose-rate effects are the result of complex network responses including genetic, epigenetic, metabolic and immunological regulation. Evidence is provided for the existence of nonlinear biological responses in the low and medium dose range as well as effects other than the classical DNA damage. Such effects may have a bearing on the quantitative and qualitative judgements on health effects induced by low dose radiations.
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