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Low-dose ionizing radiation can trigger a phenomenon known as hormesis in microorganisms, in which exposure to mild stressors like radiation results in beneficial adaptive responses. This study investigated the impact of low-dose X-rays on Escherichia coli's viability and their potential influence on antibiotic susceptibility. The irradiated samples displayed increased bacterial viability compared to non-irradiated controls, with a significant increase observed at 5 and 10 mGy of X-ray radiation exposure. This suggests a stimulating effect of low-dose ionizing radiation on E. coli's viability. To explore the correlation between viability and antibiotic susceptibility, we assessed the inhibition zone diameters for various antibiotics in non-irradiated and irradiated samples. The obtained results showed that the exposure of bacteria to low-dose ionizing radiation resulted in a significant reduction in the inhibition zone diameters for marbofloxacin, amoxicillin/clavulanic acid, ceftiofur, and cefoxitin. These findings suggest that low-dose X-ray radiation exposure can enhance E. coli's viability and its ability to withstand antibiotics, raising potential concerns.

To date, the radiation-adaptive response has been reported as a low-dose-related phenomenon and has been associated with radiation hormesis. Well-known cancers are caused by non-radiation active reactants, in addition to radiation. A model of suppression for radiation-specific cancers was previously reported, but the model did not target radiation-nonspecific cancers. In this paper, we describe kinetic models of radiation-induced suppressors for general radiation non-specific cancers, estimating the dose M that induces the maximum hormesis effect while satisfying the condition that the risk is approximately proportional to a dose above NOAEL (No Observed Adverse Effect Level). The radiation hormesis effect is maximal when the rate constant for generation of a risk-reducing factor is the same as the rate constant for its decomposition. When the two rate constants are different, the dose M at which the radiation hormesis effect is maximized depends on both rate constants, but the dose M increases as the two rate constants approach each other, reaching a maximum dose. The theory proposed in this paper can only explain existing experiments with extremely short error bar lengths. This theory may lead to the discovery of unknown risk-reducing factor at low doses and the development of risk-reducing methods in the future.

The concept of low-dose radiation (LDR)-induced hormetic responses was initially observed approximately 70 years ago and systematically reviewed along with the discovery of LDR-induced adaptive responses in a cytogenetic in vitro study in 1980s. By the end of the 1990s, discussions regarding the potential applications of LDR-induced hormesis and adaptive responses for preventing or treating chronic diseases, such as Alzheimer’s disease (AD) had taken place. Until 2016, reports on radiotherapy for the subjects with AD and for genetic AD model mice were published. Subsequently, several preclinical studies with animal models of AD and clinical studies in AD subjects were conducted. A significant milestone was achieved with the online availability of a new Systematic Review based on qualified publications from these preclinical and clinical studies. This mini-review provides a concise historical introduction to LDR-induced hormesis and adaptive responses with discussion of AD radiotherapy with either LDR or relatively high dose radiation. Highlights of this Systematic Review cover promising outcomes, challenges, and new questions, followed by discussion of potential mechanisms.

Low-dose ionizing radiation can trigger a phenomenon known as hormesis in microorganisms, in which exposure to mild stressors like radiation results in beneficial adaptive responses. This study investigated the impact of low-dose X-rays on Escherichia coli 's viability and their potential influence on antibiotic susceptibility. The irradiated samples displayed increased bacterial viability compared to non-irradiated controls, with a significant increase observed at 5 and 10 mGy of X-ray radiation exposure. This suggests a stimulating effect of low-dose ionizing radiation on E. coli 's viability. To explore the correlation between viability and antibiotic susceptibility, we assessed the inhibition zone diameters for various antibiotics in non-irradiated and irradiated samples. The obtained results showed that the exposure of bacteria to low-dose ionizing radiation resulted in a significant reduction in the inhibition zone diameters for marbofloxacin, amoxicillin/clavulanic acid, ceftiofur, and cefoxitin. These findings suggest that low-dose X-ray radiation exposure can enhance E. coli 's viability and its ability to withstand antibiotics, raising potential concerns. [ABSTRACT FROM AUTHOR]

A mathematical model for radiation hormesis below 100 mSv has previously been reported, but the origins of the formula used in the previous report were not provided. In the present paper, we first considered a sequential reaction model with identical rate constants. We showed that the function of components produced in the second step of this model agreed well with the previously reported function. Furthermore, in a general sequential reaction model with different rate constants, it was mathematically proved that the function representing the component produced in the second step is always mountain-shaped: the graph has a peak with one inflection point on either side, and such a component may induce radiation hormesis. [ABSTRACT FROM AUTHOR]

Radioactive contaminants create problems all over world, involving marine ecosystems, with their ecological importance increasing in the future. The review focuses on bioeffects of a series of alpha and beta emitting radioisotopes (americium-241, uranium-(235 + 238), thorium-232, and tritium) and gamma radiation. Low-intensity exposures are under special consideration. Great attention has been paid to luminous marine bacteria as representatives of marine microorganisms and a conventional bioassay system. This bioassay uses bacterial bioluminescence intensity as the main testing physiological parameter; currently, it is widely applied due to its simplicity and sensitivity. Dependences of the bacterial luminescence response on the exposure time and irradiation intensity were reviewed, and applicability of hormetic or threshold models was discussed. A number of aspects of molecular intracellular processes under exposure to low-intensity radiation were analyzed: (a) changes in the rates of enzymatic processes in bacteria with the bioluminescent system of coupled enzymatic reactions of NADH:FMN-oxidoreductase and bacterial luciferase taken as an example; (b) consumption of an intracellular reducer, NADH; (c) active role of reactive oxygen species; (d) repairing of the DNA damage. The results presented confirm the function of humic substances as natural radioprotectors. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen of the coronavirus disease 2019 (COVID-19), has caused more than 179 million infections and 3.8 million deaths worldwide. Global health authorities working on the COVID-19 outbreak continue to explore methods to reduce the rate of its transmission to healthy individuals. Treatment protocols thus far have focused on social distancing and masking, treatment with antivirals early in infection, and steroids to reduce the inflammatory response. An alternative approach is therapy with low dose radiation (LDR), which has several advantages compared to the current drugs and medicines. To date more than 10 case reports and pilot clinical trial preliminary outcome are available from different countries. These reports cover a wide range of patient conditions and LDR treatment strategies. Although one report showed the failure to observe the improvement of COVID-19 patients after LDR therapy, the majority showed some clinical improvement, and demonstrated the safety of LDR for COVID-19 patients, particularly with 0.5 ​Gy. This review aims to summarize the potential rationales and mechanisms of LDR therapy for COVID-19 patients, and its current clinical status and potential use.

A mathematical model for radiation hormesis below 100 mSv has previously been reported, but the origins of the formula used in the previous report were not provided. In the present paper, we first considered a sequential reaction model with identical rate constants. We showed that the function of components produced in the second step of this model agreed well with the previously reported function. Furthermore, in a general sequential reaction model with different rate constants, it was mathematically proved that the function representing the component produced in the second step is always mountain-shaped: the graph has a peak with one inflection point on either side, and such a component may induce radiation hormesis.

Aim: This work aims to investigate whether the pre-exposure to low dose/low dose rate (40 mGy, 2.2 mGy/hour) γ-radiation as a priming dose can produce a protective effect against the subsequent high one (4 Gy,.425 Gy/minute). Methods: Rats were divided into Group I (control), Group II (L); exposed to 40 mGy, Group III (H); exposed to 4 Gy, and Group IV (L+H); exposed to 40 mGy 24 hours before the exposure to 4Gy. The molecular and biochemical changes related to oxidative stress, DNA damage, apoptosis, and mitochondrial activity in the liver and testis were studied 4 hours after irradiation. Results: Exposure to 40 mGy before 4 Gy induced a significant increase in the levels of Nrf2, Nrf2 mRNA, TAC, and mitochondrial complexes I & II accompanied by a significant decrease in the levels of LPO, 8-OHdG, DNA fragmentation, TNF-α, caspase-3, and caspase-3 mRNA compared with H group. Conclusion: Exposure to low-dose γ-radiation before a high dose provides protective mechanisms that allow the body to survive better after exposure to a subsequent high one via reducing the oxidative stress, DNA damage, and apoptosis-induced early after irradiation. However, further studies are required to identify the long-term effects of this low dose. [ABSTRACT FROM AUTHOR]

Thorium is one of the most widespread radioactive elements in natural ecosystems, along with uranium, it is the most important source of nuclear energy. However, the effects of thorium on living organisms have not been thoroughly studied. Marine luminescent bacteria and their enzymes are optimal bioassays for studying low-dose thorium exposures. Luminescent bioassays provide a quantitative measure of toxicity and are characterized by high rates, sensitivity, and simplicity. It is known that the metabolic activity of bacteria is associated with the production of reactive oxygen species (ROS). We studied the effects of thorium-232 (10-11-10-3 M) on Photobacterium phosphoreum and bacterial enzymatic reactions; kinetics of bacterial bioluminescence and ROS content were investigated in both systems. Bioluminescence activation was revealed under low-dose exposures (<0.1 Gy) and discussed in terms of "radiation hormesis". The activation was accompanied by an intensification of the oxidation of a low-molecular reducer, NADH, during the enzymatic processes. Negative correlations were found between the intensity of bioluminescence and the content of ROS in bacteria and enzyme systems; an active role of ROS in the low-dose activation by thorium was discussed. The results contribute to radioecological potential of bioluminescence techniques adapted to study low-intensity radioactive exposures. [ABSTRACT FROM AUTHOR]

Abstract It has yet to be determined whether or not the probability of developing cancer due to radiation exposure levels of low doses is proportional to the dose. Herein, for radiation hormesis occurring at low doses, mathematical models using functions that take a mountain-like shape having two inflection points are considered. The following perspectives were obtained: (i) When the probability of developing cancer decreases at radiation levels above the natural background dose, the radiation hormesis effect occurs up to ~ 12.4 mSv. (ii) When there is a proportional relationship at ≥750 mSv, the radiation hormesis effect occurs up to ~ 225 mSv. Thus, by performing studies at the molecular and cellular levels for radiation doses at ≤16.8 or 307 mSv, it is possible to investigate carcinogenesis resulting from low radiation doses.

The linear no-threshold (LNT) model, which asserts that any level of ionizing radiation increases cancer risk, has been the basis of global radiation protection policies since the 1950s. Despite ongoing endorsements, a growing body of evidence challenges the LNT model, suggesting instead that low-level radiation exposure might reduce cancer risk, a concept known as radiation hormesis. This editorial examines the persistence of the LNT model despite evidence favoring radiation hormesis and proposes a solution: a public, online debate between proponents of the LNT model and advocates of radiation hormesis. This debate, organized by a government agency like Medicare, would be transparent and thorough, potentially leading to a shift in radiation protection policies. Acceptance of radiation hormesis could significantly reduce cancer mortality rates and streamline radiation safety regulations, fostering medical innovation and economic growth., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

The aim of our research was to study the effect of radon hormesis balneotherapy using natural thermal waters of Tskaltubo spring, practically, its effect on oxidant and antioxidant systems and anxiety reactions in rats. Radon is a natural gas with radioactive properties, which can have a hermetic effect when used in small doses. Radon was used to activate antioxidant mechanisms in rats, which resulted an anxiolytic effect and positively enhanced the effect of balneotherapy. To study the effect of radon in balneotherapy, groups of experimental animals (rats) were exposed to three different treatments. The radon-containing waters of Tskaltubo spring were inhaled in one group and 5 after taking the water in another group. Saline was used for inhalation in animals of the saline group. In animals of the control and sham control groups, inhalation was not used. To assess the anxiolytic effect of radon inhalation, the anxiety was induced and behavioral tests were performed (the open field and the elevated plus-maze test) after 24 h and 5 days of inhalation procedures. The anxiety test results showed that exposure to low doses of radon led to a decrease in the level of anxiety in rats. The data show that the total distance traveled by rats in the open field test after inhalation of radon was significantly greater than that by animals in the sham control and control groups. During the open field and elevated plus-maze tests, rats that had inhaled radon spent more time in the central part of the open field and on the open arms of the maze than did the other groups of rats. In the group of rats that had not inhaled radon, an increase in anxiety was observed. The basis of this reaction was an increase in the glutathione concentration. Based on our research, it can be concluded that the inhalation of small doses of radon, associated with treatments of waters from the Tskaltubo spring, activated the antioxidant systems of the body and enhanced the positive effect of balneotherapy. Clinically, this is expressed as a decrease in anxiety. Inhalation of small doses of radon activated antioxidant processes in the brain, causing an increase in glutathione/glutathione disulfide ratio in the brain. [ABSTRACT FROM AUTHOR]

Graph: Figure 2 Stress-only myocardial perfusion imaging with single photon emission computed tomography using cadmium-zinc-telluride technology for the same patients described in Figure 1, all showing normal perfusion. Accordingly, the association between a non-invasive imaging test result with other clinical and diagnostic features enables the exact definition of a warranty period individualized and tailored for each patient (Figures 1, 2, and 3). Keywords: Cadmium-zinc-telluride; coronary artery disease; myocardial perfusion imaging; radiation hormesis EN Cadmium-zinc-telluride coronary artery disease myocardial perfusion imaging radiation hormesis 1000 1004 5 07/05/21 20210601 NES 210601 See related article, doi: https://doi.org/10.1007/s12350-020-02146-9. [Extracted from the article]

The phenomenon of adaptive response is expressed in the increase of resistance of a biological object to high doses of mutagens under the conditions of previous exposure to these (or other) mutagens in low doses. Low doses of mutagen activate a number of protective mechanisms in a living object, which are called hormetic. Thus, the adaptive response and hormesis are links in the same chain. Radiation hormesis refers to the generally positive effect of low doses of low LET radiation on biological objects. The phenomenology of radiation-induced adaptive response and radiation hormesis for biological objects of different levels of organization is considered; the review of existing theories describing the dose-effect relationship has been reviewed. The hypothesis proposing one of the mechanisms of formation of radiation adaptive response of cells taking into account the conformational structure of chromatin has been submitted. The analysis of modern concepts of the phenomenon of hormesis on the basis of modeling of molecular mechanisms of formation of hormetic reactions to low-dose low LET radiation has been carried out. The parameters that can be used for quantitative and graphical evaluation of the phenomenon of hormesis was considered, and a formula for calculating the coefficient of radiation-induced adaptive response has been proposed. A review of mathematical models describing the radiation relative risk of gene mutations and neoplastic transformations at low-dose irradiation of cohorts has been performed. The following conclusions have been made: radiation hormesis and adaptive response are generally recognized as real and reproducible biological phenomena, which should be considered as very important phenomena of evolutionarily formed biological protection of living organisms from ionizing radiation. The hormesis model of dose-response relationship makes much more accurate predictions of a living object's response to radiation (or other stressors) in the low-dose range than the linear threshold (LNT) model does. The LNT model can adequately describe reactions only in the region of high doses of radiation, and, therefore, extrapolation modeling of biological object’s reactions from the zone of high doses to low doses is not correct.

Hormesis is any kind of biphasic dose-response when low doses of some agents are beneficial while higher doses are detrimental. Radiation hormesis is the most thoroughly investigated among all hormesis-like phenomena, in particular in biogerontology. In this review, we aimed to summarize research evidence supporting hormesis through exposure to low-dose ionizing radiation (LDIR). Radiation-induced longevity hormesis has been repeatedly reported in invertebrate models such as C. elegans, Drosophila and flour beetles and in vertebrate models including guinea pigs, mice and rabbits. On the contrary, suppressing natural background radiation was repeatedly found to cause detrimental effects in protozoa, bacteria and flies. We also discussed here the possibility of clinical use of LDIR, predominantly for age-related disorders, e.g., Alzheimer's disease, for which no remedies are available. There is accumulating evidence that LDIR, such as those commonly used in X-ray imaging including computer tomography, might act as a hormetin. Of course, caution should be exercised when introducing new medical practices, and LDIR therapy is no exception. However, due to the low average residual life expectancy in old patients, the short-term benefits of such interventions (e.g., potential therapeutic effect against dementia) may outweigh their hypothetical delayed risks (e.g., cancer). We argue here that assessment and clinical trials of LDIR treatments should be given priority bearing in mind the enormous economic, social and ethical implications of potentially-treatable, age-related disorders. [ABSTRACT FROM AUTHOR]

The concept of low-dose radiation (LDR)-induced hormetic responses was initially observed approximately 70 years ago and systematically reviewed along with the discovery of LDR-induced adaptive responses in a cytogenetic in vitro study in 1980s. By the end of the 1990s, discussions regarding the potential applications of LDR-induced hormesis and adaptive responses for preventing or treating chronic diseases, such as Alzheimer's disease (AD) had taken place. Until 2016, reports on radiotherapy for the subjects with AD and for genetic AD model mice were published. Subsequently, several preclinical studies with animal models of AD and clinical studies in AD subjects were conducted. A significant milestone was achieved with the online availability of a new Systematic Review based on qualified publications from these preclinical and clinical studies. This mini-review provides a concise historical introduction to LDR-induced hormesis and adaptive responses with discussion of AD radiotherapy with either LDR or relatively high dose radiation. Highlights of this Systematic Review cover promising outcomes, challenges, and new questions, followed by discussion of potential mechanisms., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

This review discusses the development of radiation countermeasure agents (RCA) in its historical progression with the description of the key radiobiological concepts and drug classifications at various stages. The rationale for classifying antiradiation drugs into two main groups, the radioprotectors/oxidomodulators and radiomodifiers/cytomodulators, which act at the two stages of radiation damage development, namely, the radiochemical and cell death stages, respectively, is provided. One way to overcome the currently observed crisis in RCA development may prove to be bringing the known efficient RCA to approvement as medical preparations by using pharmacological approaches such as combining the preparations belonging to the two groups indicated and using preparations that are able to mitigate side effects. Out of the two possible scenarios of radiation disease in humans (exposure to cosmic radiation with a dense ionizing component and delayed radiation effects) most relevant in terms of RCA search, the latter has been considered with description of the results of experiments using a model of prolonged exposure of mice to gamma-irradiation with a small dose rate. Suggestions for possible prospective directions in the field of radiobiology are provided. The conclusion has been made that there are still a lot of unresolved issues concerning the sufficiency of medicines to ensure radiation safety under various scenarios of radiation incidents. [ABSTRACT FROM AUTHOR]

The linear no-threshold (LNT) theory describes the linear relationship between a radiation dose and its effects. However, whether the linear relationship is maintained at low radiation doses has yet to be determined. Many previous studies support the radiation hormesis theory, which states that radiation has beneficial effects on health. In this viewpoint, we propose a mathematical function fitted to a model consistent with both the LNT at ≥100 mSv and radiation hormesis theories at

At low intensity, certain stress conditions may have a positive effect on growth and development of plants (eustress). Growth stimulation of barley plants after gamma irradiation of seeds in low doses was observed as an increase in root and shoot lengths. Hydrogen peroxide concentrations in shoots of irradiated plants were significantly higher than in control, while the opposite effect was observed in the roots. To elucidate the molecular basis of growth stimulation after gamma irradiation of barley seeds, we performed the transcriptomic analysis of barley embryos at different stages of seed germination. The transcriptomic data were correlated with morphological parameters and the hydrogen peroxide levels in irradiated and control plants. These data indicate that the growth stimulation by low‐dose irradiation involves the transcriptional control of genes related to phytohormones, antioxidant system, late embryogenesis abundant proteins and cell wall components, with possible involvement of jasmonate and ABA signalling. Gamma irradiation of seeds at dose 100 Gy caused significant growth inhibition and promoted expression changes in transcripts related to cell cycle arrest, DNA damage repair and antioxidant system. [ABSTRACT FROM AUTHOR]

It has yet to be determined whether or not the probability of developing cancer due to radiation exposure levels of low doses is proportional to the dose. Herein, for radiation hormesis occurring at low doses, mathematical models using functions that take a mountain-like shape having two inflection points are considered. The following perspectives were obtained: (i) When the probability of developing cancer decreases at radiation levels above the natural background dose, the radiation hormesis effect occurs up to ~ 12.4 mSv. (ii) When there is a proportional relationship at ≥750 mSv, the radiation hormesis effect occurs up to ~ 225 mSv. Thus, by performing studies at the molecular and cellular levels for radiation doses at ≤16.8 or 307 mSv, it is possible to investigate carcinogenesis resulting from low radiation doses. [ABSTRACT FROM AUTHOR]

Studies in human and mammalian cell cultures have shown that induction of DNA repair mechanisms is required for the formation of stimulation effects of low doses of ionizing radiation, named "hormesis". Nevertheless, the role of cellular defense mechanisms in the formation of radiation-induced hormesis at the level of whole organism remains poorly studied. The aim of this work was to investigate the role of genes involved in different mechanisms and stages of DNA repair in radioadaptive response and radiation hormesis by lifespan parameters in Drosophila melanogaster. We studied genes that control DNA damage sensing (D-Gadd45, Hus1, mnk), nucleotide excision repair (mei-9, mus210, Mus209), base excision repair (Rrp1), DNA double-stranded break repair by homologous recombination (Brca2, spn-B, okr) and non-homologous end joining (Ku80, WRNexo), and the Mus309 gene that participates in several mechanisms of DNA repair. The obtained results demonstrate that in flies with mutations in studied genes radioadaptive response and radiation hormesis are absent or appear to a lesser extent than in wild-type Canton-S flies. Chronic exposure of γ-radiation in a low dose during pre-imaginal stages of development leads to an increase in expression of the studied DNA repair genes, which is maintained throughout the lifespan of flies. However, the activation of conditional ubiquitous overexpression of DNA repair genes does not induce resistance to an acute exposure to γ-radiation and reinforces its negative impact. [ABSTRACT FROM AUTHOR]

Ionizing radiation is regulated by the linear no-threshold model (LNT), which asserts that the lowest doses of ionizing radiation are hazardous in proportion to the dose and dose rate. LNT is based on the data of the Life Span Study (LSS) of A-bomb survivors in Hiroshima and Nagasaki. Radiation doses of the survivors were estimated by using initial radiation (5% of blast energy) and residual radiation (10%) was neglected. The major component of residual radiation was fallout, most of which must be brought down to the ground by black rain. The rain was highly radioactive. There are three major black rain maps reporting that black rain covered wide areas of Hiroshima-City. The three lead to an important conclusion that not only A-bomb survivors but also not-in-the-city control subjects (NIC) were irradiated with residual radiation to a greater or lesser degree. This means that exposure doses in LSS were largely underestimated and that use of NIC as the negative control is faulty. Thus, LNT based on LSS is invalid. In addition, LSS ignores radiation hormesis ─ ionizing radiation is not always hazardous, but beneficial depending on doses and dose rates. Indeed, when LSS data of longevity were examined, a clear J-shaped dose-response, a hallmark of radiation hormesis, is apparent. Also, cancer mortality ratios are in the increasing order: NIC (exposed to residual radiation), A-bomb survivors (exposed to both initial and residual radiations), and the Japanese in general (no exposure). Thus, low dose radiation (LDR) is hormetic. Obstinate application of invalid LNT to regulation-unnecessary LDR has been causing tremendous human, social, and economic losses in Fukushima. Also, LNT prevents clinical application of radiation hormesis to age-associated diseases such as Alzheimer's disease and cancers. [ABSTRACT FROM AUTHOR]

The favorable responses of crop species to low-dose γ irradiation can help to develop cultivars with increased productivity and improved stress tolerance. In the present study, we tried to reveal the candidate metabolites involved in growth stimulation of barley seedlings after applying low-dose γ-radiation (60Co) to seeds. Stimulating doses (5-20 Gy) provided a significant increase in shoot length and biomass, while relatively high dose of 100 Gy led to significant inhibition of growth. Gas chromatography--mass spectrometry metabolomic analysis uncovered several compounds that may take part in radiation hormesis establishment in irradiated plants. This includes molecules involved in nitrogen redistribution (arginine, glutamine, asparagine, and γ-aminobutyric acid) and stress-responsive metabolites, such as ascorbate, myo-inositol and its derivates, and free amino acids (L-serine, β-alanine, pipecolate, and GABA). These results contribute to the understanding of the molecular mechanisms of hormesis phenomenon. [ABSTRACT FROM AUTHOR]

The discovery of X-rays and radioactivity in 1895/1896 triggered a flood of studies and applications of radiation in medicine that continues to this day. They started with imaging fractures/organs and progressed to treating diseases by exposing areas to radiation from external and internal sources. By definition, low-dose treatments stimulate damage control (or adaptive protection) systems that remedy diseases. Publications are identified on low-dose ionizing radiation (LDIR) therapies for different cancers, infections, inflammations, and autoimmune and neurodegenerative diseases. The high rate of endogenous DNA damage, due to leakage of oxygen from aerobic metabolism, and the damage control systems that deal with this are discussed. Their stimulation and inhibition by radiation are described. The radium dial painter studies revealed the radium ingestion threshold for malignancy and the dose threshold for bone sarcoma. The radiation scare that misled the medical profession and the public is a barrier to LDIR therapies. Many studies on nasal radium irradiation demonstrated that children are not unduly radiation sensitive. Omissions in the medical textbooks misinform physicians about the effects of LDIR therapy, which blocks clinical trials to determine optimal doses, efficacy, and thresholds for onset of harm. Information from many recent case reports on LDIR therapies, including successes with radon therapy, is provided. [ABSTRACT FROM AUTHOR]

Ionizing radiation is regulated by the linear no-threshold model (LNT), which asserts that the lowest doses of ionizing radiation are hazardous in proportion to the dose and dose rate. LNT is based on the data of the Life Span Study (LSS) of A-bomb survivors in Hiroshima and Nagasaki. Radiation doses of the survivors were estimated by using initial radiation (5% of blast energy) and residual radiation (10%) was neglected. The major component of residual radiation was fallout, most of which must be brought down to the ground by black rain. The rain was highly radioactive. There are three major black rain maps reporting that black rain covered wide areas of Hiroshima-City. The three lead to an important conclusion that not only A-bomb survivors but also not-in-the-city control subjects (NIC) were irradiated with residual radiation to a greater or lesser degree. This means that exposure doses in LSS were largely underestimated and that use of NIC as the negative control is faulty. Thus, LNT based on LSS is invalid. In addition, LSS ignores radiation hormesis ─ ionizing radiation is not always hazardous, but beneficial depending on doses and dose rates. Indeed, when LSS data of longevity were examined, a clear J-shaped dose-response, a hallmark of radiation hormesis, is apparent. Also, cancer mortality ratios are in the increasing order: NIC (exposed to residual radiation), A-bomb survivors (exposed to both initial and residual radiations), and the Japanese in general (no exposure). Thus, low dose radiation (LDR) is hormetic. Obstinate application of invalid LNT to regulation-unnecessary LDR has been causing tremendous human, social, and economic losses in Fukushima. Also, LNT prevents clinical application of radiation hormesis to age-associated diseases such as Alzheimer's disease and cancers. [ABSTRACT FROM AUTHOR]

Low-dose γ-irradiation can stimulate plant growth and development; however, the knowledge on the molecular mechanisms of such stimulation is yet fragmented. Irradiation of seeds leads to the mobilisation of endosperm resources and reallocation of available nitrogen to facilitate development. Based on the metabolomic analysis, several metabolites possibly involved in radiation stimulation were studied using the HPLC approach in barley cultivars after γ-irradiation of seeds. The comparison of changes in metabolite concentrations and changes in morphological traits after irradiation revealed seven metabolites that may be involved in the growth stimulation after γ-irradiation of barley seeds. Among them are free amino acids, such as γ-aminobutyric acid, β-alanine, arginine, lysine, glutamine, methionine, and a signalling compound methylglyoxal.

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We report on the application of radon inhalation therapy to patients with 4 types of cancer: colon, uterine, lung, and liver cell. The radon treatments were given to improve the efficacy of chemotherapy and were potent in all 4 cases. Marker values decreased and disease symptoms were alleviated. We include a lengthy discussion on the mechanism that may be responsible for the observed results. While employing the radon generator to treat the patient with hepatocellular carcinoma, we discovered that a concentration of 6 MBq/m3 was very effective, while 1 MBq/m3 was marginal. This implies different, and rather high, radon concentration thresholds for the treatment of different types of cancer. The evidence from these 4 cases suggests that radon inhalation may be beneficial against various cancer types as an important adjuvant therapy to conventional chemotherapy and for local high-dose radiotherapy, which would address the problem of distant metastasis. A previous case report on 2 patients with advanced breast cancer, who refused chemotherapy or radiotherapy, indicates that radon may be effective as a primary therapy for cancer. Clinical trials should be carried out to determine the best radon concentrations for treatment of other types of cancer, at different stages of progression. [ABSTRACT FROM AUTHOR]

Radiation hormesis is a phenomenon in which low doses of ionizing radiation can have stimulatory effects on biological systems. The temperate brown alga Sargassum horneri was the subject of this study on the hormetic effects of low-dose 60Co gamma radiation on macroalgae incubated in vitro at high temperatures. Sargassum horneri embryos were irradiated with 15, 20, and 25 Gy 60Co radiation and then incubated in vitro at 18, 21, 24, 27, and 30 °C. The same radiation treatment was also applied to S. horneri embryos grown in situ in outdoor mass cultivation. Non-irradiated in vitro control cultures had optimal growth at 21 °C, but irradiated cultures had optimal growth at 27 °C and growth was significantly enhanced by 32% compared to the control cultures at 21 °C. In contrast, in situ cultures of S. horneri in outdoor 10-ton seawater tanks showed that irradiated thalli had less total biomass as compared to non-irradiated control thalli. While low doses of gamma radiation may induce high-temperature tolerance resulting in better growth rates under the highly controlled in vitro culture conditions, these effects were not clearly observed in the in situ outdoor mass-cultivation. [ABSTRACT FROM AUTHOR]

Background: Hormesis is defined as the bio-positive response of something which is bio-negative in high doses. In the present study, the effect of radiation hormesis was evaluated on the survival rate of immunosuppressed BALB/c mice by Cyclosporine A. Material and Methods: We used 75 consanguine, male, BALB/c mice in this experiment. The first group received Technetium-99m (3700Bq) and the second group was placed on a sample radioactive soil of Ramsar region (800Bq) for 20 days. The third group was exposed to X-rays (3600Bq) and the fourth group was placed on the radioactive soil and then injected Technetium-99m. The last group was the sham irradiated control group. Finally, 30mg Cyclosporine A as the immunosuppressive agent was orally administered to all mice 48 hours after receiving X-rays and Technetium99m. The mean survival rate of mice in each group was estimated during time. Results: A log rank test was run to determine if there were differences in the survival distribution for different groups and related treatments. According to the results, the survival rate of all pre-irradiated groups was more than the sham irradiated control group (p < .05). The highest survival time was related to the mice which were placed on the radioactive soil of Ramsar region for 20 days and then injected Technetium99m. Conclusion: This study confirmed the presence of hormetic models and the enhancement of survival rate in immunosuppressed BALB/c mice as a consequence of low-dose irradiation. It is also revealed the positive synergetic radioadaptive response on survival rate of immunosuppressed animals.

This article describes positive and negative aspects of ionizing radiation and its effects on human body. Being a part of various medical procedures in medicine, ionising radiation has become an important aspect for both medical practitioners and patients. Commonly used in treatment, diagnostics and interventional radiology, its medical usage follows numerous rules, designed to reduce excessive exposure to ionizing radiation. Its widespread use makes it extremely important to research and confirm effects of various doses of radiation on patients of all ages. Two scientific theories, explaining radiation effects on human organism, stand in contrast: commonly accepted LNT-hypothesis and yet to be proven hormesis theory. Despite the fact that the current radiation protection standards are based on the linear theory (LNT-hypothesis), the hormesis theory arouses more and more interest, and numerous attempts are made to prove its validity. Further research expanding the knowledge on radiation hormesis can change the face of the future. Perhaps such researches will open up new possibilities for the use of ionizing radiation, as well as enable the calculation of the optimal and personalised radiation dose for each patient, allowing us to find a new “golden mean”. The authors therefore are careful and believe that these methods have a large future, primarily patient’s good should however be kept in mind.

Background. Spa reaction is an adaptive response of an organism, emerging as a result of external factors. It is a positive element of spa therapy leading to metabolic changes, which are important for the body. The effect of these changes is an increase in immune activity and regenerative reactions of the body. The mechanism of the response is not fully known. Objectives. The aim of the study was to evaluate the changes observed in the field of the integrated antioxidant system of the body in the course of radon therapy, especially in reference to spa reaction. Material and methods. The study was conducted in the health resort in Świeradów-Zdrój. The observation regarded patients undergoing treatment with radon water. Before the treatment, after 5 and 18 days of treatment, the total antioxidant status (TAS) was evaluated with the use of a standard colorimetric assay. The study group consisted of 35 patients with degenerative joints and disc disease. The control group consisted of 15 people selected from the employees of the spa, also suffering from osteoarthritis, who did not undergo radon therapy (without contact with radon). Results. On the 5th day of the treatment, in both groups, the TAS increase was observed with significantly worse results in the control group. After the treatment, in the study group, an increase in TAS was observed, whereas in the control group, a significant decrease in the TAS concentration was noted. Conclusions. A beneficial effect of radon treatments on the growth of TAS in the body of the patients treated in the spa was demonstrated. The increase in the TAS concentration on the 5th day of treatment may indicate the relationship between these changes and the phenomenon of spa response. The changes are a result of low doses of ionizing radiation originating from radon dissolved in medicinal water, used in the course of the therapy. [ABSTRACT FROM AUTHOR]

We have demonstrated for the first time that a single exposure to γ-radiation at a dose of 3 cGy on HELF-104 human embryonic lung fibroblasts in early passages leads to the delayed stimulation of proliferation of the progeny of irradiated cells by 30-37 days. Moreover, the general changes in dynamics of proliferation after irradiation with low doses (3 and 5 cGy) are more pronounced than after high-dose irradiation (2 Gy). We suggest that this effect may play an important role in the formation of the specific effects of low doses of ionizing radiation, as detected by integral endpoints at higher levels of organization of living matter. [ABSTRACT FROM AUTHOR]