Quantification of Adaptive Protection Following Low-dose Irradiation

Feinendegen, L. E.

doi:10.1097/hp.0000000000000431

Cited by 35 publications

(26 citation statements)

References 16 publications

(25 reference statements)

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“…Repeated low dose radiation appears to induce adaptive mechanisms that result in protection and reduces the risk to develop cancer [64]. A meta-analysis of 18 studies performed between 1986 and 2012 showed that in mice doses between 0–100 mGy results in protection, whereas above 100 mGy the probability to induce damage is higher than the possibility of damage reduction [65]. Furthermore, in medical professionals working with radiation before 1950, a high death rate due to leukemia was seen, while after 1950, when the maximal exposure limit was reduced from 30,000 mSv/year to 50 mSv/year, medical professionals working with radiation have lower mortality rates than other medical specialists not working with radiation [66].…”

Section: Effects Of Hormesis—remodeling Of the Gsh Systemmentioning

confidence: 99%

Time in Redox Adaptation Processes: From Evolution to Hormesis

Sthijns

Weseler

Bast

et al. 2016

IJMS

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Life on Earth has to adapt to the ever changing environment. For example, due to introduction of oxygen in the atmosphere, an antioxidant network evolved to cope with the exposure to oxygen. The adaptive mechanisms of the antioxidant network, specifically the glutathione (GSH) system, are reviewed with a special focus on the time. The quickest adaptive response to oxidative stress is direct enzyme modification, increasing the GSH levels or activating the GSH-dependent protective enzymes. After several hours, a hormetic response is seen at the transcriptional level by up-regulating Nrf2-mediated expression of enzymes involved in GSH synthesis. In the long run, adaptations occur at the epigenetic and genomic level; for example, the ability to synthesize GSH by phototrophic bacteria. Apparently, in an adaptive hormetic response not only the dose or the compound, but also time, should be considered. This is essential for targeted interventions aimed to prevent diseases by successfully coping with changes in the environment e.g., oxidative stress.

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Section: Effects Of Hormesis—remodeling Of the Gsh Systemmentioning

confidence: 99%

Time in Redox Adaptation Processes: From Evolution to Hormesis

Sthijns

Weseler

Bast

et al. 2016

IJMS

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“…2 These generally are referred to as "Protective Responses," an expression of system of adaptation. 11 They tend to result in bodily benefit of various types-under genetic control, which also reflect individual differences to radiation sensitivity. Adaptive protection appears measurable down to about 10 mGy above background radiation doses.…”

Section: The Double Thresholdmentioning

confidence: 99%

The Double Threshold: Consequences for Identifying Low-Dose Radiation Effects

Waltar

Feinendegen

2020

Dose-Response

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Prior to observing low-dose-induced cell signaling and adaptive protection, radiogenic stochastic effects were assumed to be linearly related to absorbed dose. Now, abundant data prove the occurrence of radiogenic adaptive protection specifically at doses below ∼ 200 mGy (with some data suggesting such protection at a dose even higher than 200 mGy). Moreover, cells do not thrive properly when deprived of radiation below background dose. Two threshold doses need be considered in constructing a valid dose-response relationship. With doses beginning to rise from zero, cells increasingly escape radiation deprivation. The dose at which radiation-deprived cells begin to function homeostatically provides dose Threshold A. With further dose increase, adaptive protection becomes prominent and then largely disappears at acute doses above ∼ 200 mGy. The dose at which damage begins to override protection defines Threshold B. Thresholds A and B should be terms in modeling dose-response functions. Regarding whole-body responses, current data suggest for low-LET acute, non-chronic, irradiation a Threshold B of about 100 mGy prevails, except for leukemia and probably some other malignancies, and for chronic, low dose-rate irradiation where the Threshold B may well reach 1 Gy per year. A new Research and Development Program should determine individual Thresholds A and B for various radiogenic cell responses depending on radiation quality and target.

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“…Recently, Feinendegen [31] summarized 18 studies investigating the effects of acute low-dose radiation at the molecular, cellular, or tissue-cancer levels, with 54 data points at doses ≤ 700 mGy, and attempted to quantify adaptive radioprotections. Only two points below 400 mGy showed damage causation, and one point showed zero effect; these observations stemmed from transgenic mice.…”

Section: Biological Studies Of Radiation Hormesismentioning

confidence: 99%

Overview of Biological, Epidemiological, and Clinical Evidence of Radiation Hormesis

Shibamoto

Nakamura

2018

IJMS

104

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The effects of low-dose radiation are being increasingly investigated in biological, epidemiological, and clinical studies. Many recent studies have indicated the beneficial effects of low doses of radiation, whereas some studies have suggested harmful effects even at low doses. This review article introduces various studies reporting both the beneficial and harmful effects of low-dose radiation, with a critique on the extent to which respective studies are reliable. Epidemiological studies are inherently associated with large biases, and it should be evaluated whether the observed differences are due to radiation or other confounding factors. On the other hand, well-controlled laboratory studies may be more appropriate to evaluate the effects of low-dose radiation. Since the number of such laboratory studies is steadily increasing, it will be concluded in the near future whether low-dose radiation is harmful or beneficial and whether the linear-no-threshold (LNT) theory is appropriate. Many recent biological studies have suggested the induction of biopositive responses such as increases in immunity and antioxidants by low-dose radiation. Based on recent as well as classical studies, the LNT theory may be out of date, and low-dose radiation may have beneficial effects depending on the conditions; otherwise, it may have no effects.

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Quantification of Adaptive Protection Following Low-dose Irradiation

Cited by 35 publications

References 16 publications

Time in Redox Adaptation Processes: From Evolution to Hormesis

Time in Redox Adaptation Processes: From Evolution to Hormesis

The Double Threshold: Consequences for Identifying Low-Dose Radiation Effects

Overview of Biological, Epidemiological, and Clinical Evidence of Radiation Hormesis

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