Protection against radiation-induced oxidative stress in cultured human epithelial cells by treatment with antioxidant agents

Ionizing Radiation-Induced Oxidative Stress in Computed Tomography-Effect of Vitamin C on Prevention of DNA Damage: PREVIR-C Randomized Controlled Trial Study Protocol

Exposure to ionizing radiation (IR) is inevitable in various X-ray imaging examinations, with computed tomography (CT) being a major contributor to increased human radiation exposure. Ionizing radiation may cause structural damage to macromolecules, particularly DNA, mostly through an indirect pathway in diagnostic imaging. The indirect pathway primarily involves the generation of reactive oxygen species (ROS) due to water radiolysis induced by IR, leading to DNA damage, including double-strand breaks (DSB), which are highly cytotoxic. Antioxidants, substances that prevent oxidative damage, are proposed as potential radioprotective agents. This Study Protocol article presents the rationale for selecting vitamin C as a preventive measure against CT-associated IR-induced DNA damage, to be investigated in a randomized placebo-controlled trial, with a full in vivo design, using an oral easy-to-use schedule administration in the outpatient setting, for the single CT examination with the highest total global IR dose burden (contrast-enhanced abdomen and pelvis CT). The study also aims to explore the mediating role of oxidative stress, and it has been written in adherence to the Standard Protocol Items recommendations.

Comparison of the radioprotective effects of the liposomal forms of five natural radioprotectants in alleviating the adverse effects of ionising irradiation on human lymphocytes and skin cells in radiotherapy

This study aims to evaluate the radioprotective effects of liposomes encapsulating curcumin (Lip-CUR), silibinin (Lip-SIL), α-tocopherol (Lip-TOC), quercetin (Lip-QUE) and resveratrol (Lip-RES) in alleviating the adverse effects of ionising irradiation on human lymphoctyes and skin cells in radiotherapy. Liposomes encapsulating the above natural radioprotectants (Lip-NRPs) were prepared by the film hydration method combined with sonication. Their radioprotective effects for the cells against X-irradiation was evaluated using trypan-blue assay and γ-H2AX assay. All prepared Lip-NRPs had a mean diameter less than 240 nm, polydispersity index less than 0.32, and zeta potential more than -23 mV. Among them, the radioprotective effect of Lip-RES was lowest, while that of Lip-QUE was highest. Lip-SIL also exhibited a high radioprotective effect despite its low DPPH-radical scavenging activity (12.9%). The radioprotective effects of Lip-NRPs do not solely depend on the free radical scavenging activity of NRPs but also on their ability to activate cellular mechanisms.

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

Oral administration of inorganic nitrate alleviated biological damage induced by cone-beam computed tomography examination in Wistar rats

OBJECTIVES

To explore whether the inorganic nitrate has a protective effect on biological damage induced by cone-beam computed tomography (CBCT) and compare it with Vitamin C.

MATERIALS AND METHODS

Sixty Wistar rats were randomly separated into 6 groups: control group, irradiation (IR) group, NaNO₃ group, IR + NaNO₃ group, Vitamin C group, and IR + Vitamin C group. Rats were whole-body irradiated with CBCT four times. The absorbed dose of the skin surface was measured using thermoluminescent dosemeter chips and the mean whole-body absorbed dose was calculated. Peripheral blood was collected at 0.5h and 24h after irradiation. Bodyweight and organ index of rats before and after irradiation were analyzed. The bone marrow was taken for micronucleus test. Lymphocytes were isolated from peripheral blood for γ-H2AX immunofluorescence assay, apoptosis and reactive oxygen species (ROS) analysis. Total antioxidant capacity (TAC), malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were detected.

RESULTS

The mean absorbed dose of four whole-body CBCT scans for rats was 73.04 mGy. Bodyweight and organ index before and after irradiation with X-ray had no significant differences. The micronuclei frequency of IR + NaNO3 and IR + Vitamin C groups showed a significant decrease than that in the IR group, which was not significantly different from that of the control group. The γ-H2AX foci rates in the IR + NaNO3 group and the IR + Vitamin C group were significantly lower than that in the IR group. In addition, the foci rate of the IR + NaNO3 group returned to the baseline level of the control group 24h after CBCT scanning. The apoptosis of lymphocytes in rats did not increase. The IR + NaNO3 group (P < 0.001) or IR + Vitamin C group (P < 0.001) showed a significant increase in ROS positive cells rate with the control group, while were significantly lower than those in the IR group (P < 0.01). In addition, the ROS-positive cell rate in the IR + NaNO3 group was significantly lower than that in the IR + Vitamin C group. The MDA in the serum of rats increased significantly, while SOD and TAC decreased significantly at 0.5h after irradiation.

CONCLUSIONS

Compared with Vitamin C, inorganic nitrate had better preventive effects on biological damage induced by CBCT scans in rats.

Novel nanotech antioxidant cocktail prevents medical diagnostic procedures ionizing radiation effects

Ionizing radiation (IR) exposure results in oxidative damage causing cytotoxic and genotoxic effects. Double-strand breaks (DSBs) are considered the most significant DNA lesions induced by ionizing radiation. The present study evaluates the radio protective effect of a novel antioxidant cocktail through quantification of DSB in peripheral blood lymphocytes (PBL) in vivo. The study included 16 consecutive patients who were divided into 2 groups, 6 patients received the novel antioxidant cocktail and 10 control patients. Blood samples were drawn from the patients undergoing bone scan, before the injection of the ^99mTc MDP tracer and 2 h after the injection. Quantification of the IR damage was done by Immunofluorescence analysis of the phosphorylated histone, γ-H2AX, used to monitor DSB induction and repair in PBL. The radiation effect of the control group was measured by 2 variables, the average DBSs foci per nucleus and the percent of the DSB bearing cells in PBL. The findings showed a significant increase in the DSBs after isotope injection with an average increment of 0.29 ± 0.13 of foci/nucleus and 17.07% ± 7.68 more DSB bearing cells (p < 0.05). The cocktail treated group showed a lower difference average of − 2.79% ± 6.13 DSB bearing cells. A paired t-test revealed a significant difference between the groups (p < 0.005) confirming the cocktail’s protective effect. The novel anti-oxidant treatment decreases the oxidative stress-induced DNA damage and can be considered as a preventative treatment before radiation exposure.

Confirmation of efficacy, elucidation of mechanism, and new search for indications of radon therapy

Indications of radon therapy include various diseases related to respiratory, painful, digestive, chronic degenerative, senile, etc. derived from reactive oxygen species, but most are based on empirical prescriptions. For this reason, we have evaluated the relation between the biological response caused by radon and the tissue/organ absorbed dose more quantitatively, and have promoted the elucidation of mechanisms related to the indication and searching newly. As a result, as a mechanism, a series of moderate physiological stimulative effects accompanying a small amount of oxidative stress by radon inhalation are being elucidated. That is, hyperfunction of anti-oxidation/immune regulation/damage repair, promotion of anti-inflammation/circulating metabolism/hormone secretion, induction of apoptosis/heat shock protein, etc. Also, new indications include inflammatory/neuropathic pain, hepatic/renal injury, colitis, type 1 diabetes, complication kidney injury, hyperuricemia, transient cerebral ischemia, and inflammatory edema. Furthermore, we examined the combined antioxidant effect of radon inhalation and antioxidants or therapeutic agents. As a result, it was clear that any combination treatment could enhance the suppression effect of disease. It can be expected that radon therapy can be used effectively by applying it in addition to usual treatment, since reduction in its dosage can also be expected by concomitant use for drugs with strong side effects.

Effect of Different Antioxidants on X-ray Induced DNA Double-strand Breaks Using γ-H2AX in Human Blood Lymphocytes

Ionizing radiation exposure produces direct or indirect biological effects on genomic DNA. The latter are ionizing radiation mediated by induction of free radicals and oxygen species (ROS). The study was conducted to evaluate the dose-effect/time-effect of antioxidant treatments in reducing the induction of double-strand breaks in human blood lymphocytes. Human peripheral blood samples of 2 mL each from healthy donors were irradiated with 10 mGy after pre-incubation with different antioxidants (β-carotene, vitamin E, vitamin C, N-acetyl L-cysteine). In order to assess their efficiency as prophylactic therapy for irradiation, various concentrations and combinations of antioxidants, as well as different incubation times, have been evaluated. To assess double-strand breaks induced by ionizing radiation, the phosphorylated histone γ-H2AX has been used. A significant reduction (p < 0.001) in double-strand breaks studied with a γ-H2AX assay was observed with N-acetyl L-cysteine with a 1-h incubation time, followed by vitamin C, vitamin E, and β-carotene. The use of antioxidants, especially N-acetyl L-cysteine before irradiation, significantly decreased the occurrence of double-strand breaks, demonstrating the potential radiological protection for exposure to ionizing radiation.

The effect of prophylactic oral vitamin C use on DNA double-strand breaks after abdominal contrast-enhanced CT: A preliminary study

PURPOSE

To investigate the protective effect of oral Vitamin C on DNA double-strand breaks (DSBs) after abdominal contrast-enhanced CT examination.

MATERIALS AND METHODS

Sixty patients undergoing abdominal multiphase contrast-enhanced CT were divided into control group (n = 30) and prevention group (n = 30). Patients in the prevention group were orally administered 1 g Vitamin C 30-120 minutes prior to CT examination. Blood samples were obtained prior to and 5 min following CT examination for each subject. γ-H2AX foci representing DSBs in the nucleus of lymphocytes were marked by fluorescent markers. Change in γ-H2AX foci/cell was compared through Student t-tests or ANOVA testing. The relationship between physical parameters and increase in γ-H2AX foci was analyzed through Pearson or Spearman correlation analysis.

RESULTS

The mean increase in γ-H2AX was 0.49 foci /cell in the control group and 0.19 foci/cell in the prevention group (p < 0.001), corresponding to a 61% reduction in the mean increase in γ-H2AX foci in the prevention group compared to the control group. In the prevention group, increase in γ-H2AX foci/cell positively correlated with dose length product and volume CT dose index (r = 0.449 and 0.403, respectively; both p < 0.05). No difference in the increase in γ-H2AX foci/cell was found between the different time interval subgroups of 30, 60, and 120 min between Vitamin C administration and CT examination (p > 0.05).

CONCLUSION

Oral Vitamin C can significantly reduce the level of DSBs after abdominal contrast-enhanced CT examination and is a simple and effective method to decrease DNA damage.

Fractionated whole body gamma irradiation modulates the hepatic response in type II diabetes of high fat diet model rats

HFD animals were exposed to a low rate of different fractionated whole body gamma irradiation doses (0.5, 1 and 2 Gy, three fractions per week for two consecutive months) and the expression of certain genes involved in type 2 diabetes mellitus (T2DM) in livers and brains of HFD Wistar rats was investigated. Additionally, levels of diabetes-related proteins encoded by the studied genes were analyzed. Results indicated that mRNA level of incretin glucagon like peptite-1 receptor (GLP-1R) was augmented in livers and brains exposed to 1 and 2 Gy doses. Moreover, the mitochondrial uncoupling proteins 2 and 3 (UCP2/3) expressions in animals fed on HFD compared to those fed on normal chow diet were significantly increased at all applied doses. GLP-1R and UCP3 protein levels were up regulated in livers. Total protein content increased at 0.5 and 1 Gy gamma irradiation exposure and returned to its normal level at 2 Gy dose. Results could be an indicator of type 2 diabetes delayed development during irradiation exposure and support the importance of GLP-1R as a target gene in radiotherapy against T2DM and its chronic complications. A new hypothesis of brain-liver and intestine interface is speculated by which an increase in the hepatic GLP-1R is influenced by the effect of fractionated whole body gamma irradiation.

Radioprotective agents to prevent cellular damage due to ionizing radiation

Medical imaging has become a central component of patient care to ensure early and accurate diagnosis. Unfortunately, many imaging modalities use ionizing radiation to generate images. Ionizing radiation even in low doses can cause direct DNA damage and generate reactive oxygen species and free radicals, leading to DNA, protein, and lipid membrane damage. This cell damage can lead to apoptosis, necrosis, teratogenesis, or carcinogenesis. As many as 2% of cancers (and an associated 15,000 deaths annually) can be linked to computed tomography exposure alone. Radioprotective agents have been investigated using various models including cells, animals, and recently humans. The data suggest that radioprotective agents working through a variety of mechanisms have the potential to decrease free radical damage produced by ionizing radiation. Radioprotective agents may be useful as an adjunct to medical imaging to reduced patient morbidity and mortality due to ionizing radiation exposure. Some radioprotective agents can be found in high quantities in antioxidant rich foods, suggesting that a specific diet recommendation could be beneficial in radioprotection.

Тhe Impact Of Positive Acceleration (+Gz) on Antioxidant Capacity and Histopathological Alterations in Different Organs and Tissues in Rats

Since the early 1940s, a significant amount of research has been conducted to describe the impact of the high-G acceleration on the cardiovascular system. The objective of the present study was to examine the role of the antioxidant enzyme system under biodynamic stress in the liver, heart and gastric mucosa in response to high-magnitude +Gz exposure in a rat model. Twenty adult male Wistar albino rats (10 rats per group; 9-11 weeks old, 200-250 g b.w.) were divided into the following two groups: control and G (exposed to a biodynamic stress model under positive (+7 Gz) acceleration for 40 s). The influence of acute biodynamic stress on pro-oxidative parameters in the rat liver (xanthine oxidase (XOD), catalase (CAT), peroxidase (Px), glutathione peroxidase (GSH-Px), total content of glutathione (GSH), lipid peroxidation (LPx)) and on histopathological alterations in the liver, cardiac muscle and gastric mucosa was examined. Biodynamic stress resulting from positive (+7 Gz) acceleration resulted in a highly statistically signifi cant increase of CAT GSH-Px activity compared to the control group. The LPx levels were significantly decreased, but the GSH contents and the activities of other enzymes were not significantly changed. Significant microscopic changes in the liver, heart and gastric mucosa were observed in the G group. These results clearly indicate that +Gz acceleration alters biochemical systems. These alterations in cellular processes may be mediated by influences of hypoxia or ischaemia via changes in the antioxidant capacity.

A New Natural Antioxidant Mixture Protects against Oxidative and DNA Damage in Endothelial Cell Exposed to Low-Dose Irradiation

Exposure to ionizing radiation during diagnostic procedures increases systemic oxidative stress and predisposes to higher risk of cancer and cardiovascular disease development. Many studies indicated that antioxidants protect against radiation-induced damage and have high efficacy and lack of toxicity in preventing radiation exposure damages. The purpose of this study was to investigate the in vitro protective effect of a new antioxidant mixture, named RiduROS, on oxidative stress generation and DNA double-strand breaks (DSBs) induced by low doses of X-rays in endothelial cells. Human umbilical vein endothelial cells (HUVEC) were treated with RiduROS mixture 24 h before a single exposure to X-rays at an absorbed dose of 0.25 Gy. The production of reactive oxygen species (ROS) was evaluated by fluorescent dye staining and nitric oxide (NO) by the Griess reaction, and DSBs were evaluated as number of γ-H2AX foci. We demonstrated that antioxidant mixture reduced oxidative stress induced by low dose of X-ray irradiation and that RiduROS pretreatment is more effective in protecting against radiation-induced oxidative stress than single antioxidants. Moreover, RiduROS mixture is able to reduce γ-H2AX foci formation after low-dose X-ray exposure. The texted mixture of antioxidants significantly reduced oxidative stress and γ-H2AX foci formation in endothelial cells exposed to low-dose irradiation. These results suggest that RiduROS could have a role as an effective radioprotectant against low-dose damaging effects.

Influence of Different Antioxidants on X-Ray Induced DNA Double-Strand Breaks (DSBs) Using γ-H2AX Immunofluorescence Microscopy in a Preliminary Study

Background

Radiation exposure occurs in X-ray guided interventional procedures or computed tomography (CT) and γ-H2AX-foci are recognized to represent DNA double-strand breaks (DSBs) as a biomarker for radiation induced damage. Antioxidants may reduce the induction of γ-H2AX-foci by binding free radicals. The aim of this study was to establish a dose-effect relationship and a time-effect relationship for the individual antioxidants on DSBs in human blood lymphocytes.

Materials and Methods

Blood samples from volunteers were irradiated with 10 mGy before and after pre-incubation with different antioxidants (zinc, trolox, lipoic acid, ß-carotene, selenium, vitamin E, vitamin C, N-acetyl-L-cysteine (NAC) and Q 10). Thereby, different pre-incubation times, concentrations and combinations of drugs were evaluated. For assessment of DSBs, lymphocytes were stained against the phosphorylated histone variant γ-H2AX.

Results

For zinc, trolox and lipoic acid regardless of concentration or pre-incubation time, no significant decrease of γ-H2AX-foci was found. However, ß-carotene (15%), selenium (14%), vitamin E (12%), vitamin C (25%), NAC (43%) and Q 10 (18%) led to a significant reduction of γ-H2AX-foci at a pre-incubation time of 1 hour. The combination of different antioxidants did not have an additive effect.

Conclusion

Antioxidants administered prior to irradiation demonstrated the potential to reduce γ-H2AX-foci in blood lymphocytes.

Potent radioprotective effects of combined regimens of famotidine and vitamin C against radiation-induced micronuclei in mouse bone marrow erythrocytes

To investigate the radioprotective effect of the combination of famotidine and vitamin C against radiation-induced micronucleus formation in mouse bone marrow erythrocytes, various doses of famotidine or vitamin C or combinations thereof were administered intraperitoneally to adult male NMRI mice 2 h before 2 and 4 Gy γ-irradiation. The frequency of micronucleated polychromatic erythrocytes (MnPCEs) was scored in 5,000 polychromatic erythrocytes (PCEs), and the cell proliferation ratio [PCE/(PCE + NCE); NCE = normochromatic erythrocytes] was also calculated for each treatment group. Data were statistically evaluated using one-way ANOVA test. The results show that pretreatment with various doses of famotidine and vitamin C before γ-irradiation significantly reduced the frequency of MnPCEs with a protection factor (PF) of 2 and 1.7, respectively. Pretreatment with vitamin C also significantly increased the cell proliferation ratio, while famotidine had no effect. Combination of famotidine and vitamin C was more effective in reducing MnPCEs than each compound alone, leading to a PF of 4.3 after irradiation. Cell proliferation ratio was also significantly improved by the combination compared with the irradiated control groups. Both famotidine and vitamin C are potent scavengers of free radicals and reactive oxygen species, especially OH(·). The combination of the two compounds probably further enhances this activity, thus leading to high bone marrow protection.

Broad-spectrum antibiotic or G-CSF as potential countermeasures for impaired control of bacterial infection associated with an SPE exposure during spaceflight

A major risk for astronauts during prolonged space flight is infection as a result of the combined effects of microgravity, situational and confinement stress, alterations in food intake, altered circadian rhythm, and radiation that can significantly impair the immune system and the body’s defense systems. We previously reported a massive increase in morbidity with a decrease in the ability to control a bacterial challenge when mice were maintained under hindlimb suspension (HS) conditions and exposed to solar particle event (SPE)-like radiation. HS and SPE-like radiation treatment alone resulted in a borderline significant increase in morbidity. Therefore, development and testing of countermeasures that can be used during extended space missions in the setting of exposure to SPE radiation becomes a serious need. In the present study, we investigated the efficacy of enrofloxacin (an orally bioavailable antibiotic) and Granulocyte colony stimulating factor (G-CSF) (Neulasta) on enhancing resistance to Pseudomonas aeruginosa infection in mice subjected to HS and SPE-like radiation. The results revealed that treatment with enrofloxacin or G-CSF enhanced bacterial clearance and significantly decreased morbidity and mortality in challenged mice exposed to suspension and radiation. These results establish that antibiotics, such as enrofloxacin, and G-CSF could be effective countermeasures to decrease the risk of bacterial infections after exposure to SPE radiation during extended space flight, thereby reducing both the risk to the crew and the danger of mission failure.

Hippocampal dysfunctions caused by cranial irradiation: a review of the experimental evidence

Cranial irradiation (IR) is commonly used for the treatment of brain tumors but may cause disastrous brain injury, especially in the hippocampus, which has important cognition and emotional regulation functions. Several preclinical studies have investigated the mechanisms associated with cranial IR-induced hippocampal dysfunction such as memory defects and depression-like behavior. However, current research on hippocampal dysfunction and its associated mechanisms, with the ultimate goal of overcoming the side effects of cranial radiation therapy in the hippocampus, is still very much in progress. This article reviews several in vivo studies on the possible mechanisms of radiation-induced hippocampal dysfunction, which may be associated with hippocampal neurogenesis, neurotrophin and neuroinflammation. Thus, this review may be helpful to gain new mechanistic insights into hippocampal dysfunction following cranial IR and provide effective strategies for potential therapeutic approaches for cancer patients receiving radiation therapy.

Coenzyme Q10 benefits symptoms in Gulf War veterans: results of a randomized double-blind study

We sought to assess whether coenzyme Q10 (CoQ10) benefits the chronic multisymptom problems that affect one-quarter to one-third of 1990-1 Gulf War veterans, using a randomized, double-blind, placebo-controlled study. Participants were 46 veterans meeting Kansas and Centers for Disease Control criteria for Gulf War illness. Intervention was PharmaNord (Denmark) CoQ10 100 mg per day (Q100), 300 mg per day (Q300), or an identical-appearing placebo for 3.5 ± 0.5 months. General self-rated health (GSRH), the primary outcome, differed across randomization arms at baseline, and sex significantly predicted GSRH change, compelling adjustment for baseline GSRH and prompting sex-stratified analysis. GSRH showed no significant benefit in the combined-sex sample. Among males (85% of participants), Q100 significantly benefited GSRH versus placebo and versus Q300, providing emphasis on Q100. Physical function (summary performance score, SPS) improved on Q100 versus placebo. A rise in CoQ10 approached significance as a predictor of improvement in GSRH and significantly predicted SPS improvement. Among 20 symptoms each present in half or more of the enrolled veterans, direction-of-difference on Q100 versus placebo was favorable for all except sleep problems; sign test 19:1, p=0.00004) with several symptoms individually significant. Significance for these symptoms despite the small sample underscores large effect sizes, and an apparent relation of key outcomes to CoQ10 change increases prospects for causality. In conclusion, Q100 conferred benefit to physical function and symptoms in veterans with Gulf War illness. Examination in a larger sample is warranted, and findings from this study can inform the conduct of a larger trial.

Biological Effects of Space Radiation and Development of Effective Countermeasures

As part of a program to assess the adverse biological effects expected from astronaut exposure to space radiation, numerous different biological effects relating to astronaut health have been evaluated. There has been major focus recently on the assessment of risks related to exposure to solar particle event (SPE) radiation. The effects related to various types of space radiation exposure that have been evaluated are: gene expression changes (primarily associated with programmed cell death and extracellular matrix (ECM) remodeling), oxidative stress, gastrointestinal tract bacterial translocation and immune system activation, peripheral hematopoietic cell counts, emesis, blood coagulation, skin, behavior/fatigue (including social exploration, submaximal exercise treadmill and spontaneous locomotor activity), heart functions, alterations in biological endpoints related to astronaut vision problems (lumbar puncture/intracranial pressure, ocular ultrasound and histopathology studies), and survival, as well as long-term effects such as cancer and cataract development. A number of different countermeasures have been identified that can potentially mitigate or prevent the adverse biological effects resulting from exposure to space radiation.

Dramatic increase in oxidative stress in carbon-irradiated normal human skin fibroblasts

Skin complications were recently reported after carbon-ion (C-ion) radiation therapy. Oxidative stress is considered an important pathway in the appearance of late skin reactions. We evaluated oxidative stress in normal human skin fibroblasts after carbon-ion vs. X-ray irradiation. Survival curves and radiobiological parameters were calculated. DNA damage was quantified, as were lipid peroxidation (LPO), protein carbonylation and antioxidant enzyme activities. Reduced and oxidized glutathione ratios (GSH/GSSG) were determined. Proinflammatory cytokine secretion in culture supernatants was evaluated. The relative biological effectiveness (RBE) of C-ions vs. X-rays was 4.8 at D₀ (irradiation dose corresponding to a surviving fraction of 37%). Surviving fraction at 2 Gy (SF2) was 71.8% and 7.6% for X-rays and C-ions, respectively. Compared with X-rays, immediate DNA damage was increased less after C-ions, but a late increase was observed at D_10% (irradiation dose corresponding to a surviving fraction of 10%). LPO products and protein carbonyls were only increased 24 hours after C-ions. After X-rays, superoxide dismutase (SOD) activity was strongly increased immediately and on day 14 at D_0% (irradiation dose corresponding to a surviving fraction of around 0%), catalase activity was unchanged and glutathione peroxidase (GPx) activity was increased only on day 14. These activities were decreased after C-ions compared with X-rays. GSH/GSSG was unchanged after X-rays but was decreased immediately after C-ion irradiation before an increase from day 7. Secretion of IL-6 was increased at late times after X-ray irradiation. After C-ion irradiation, IL-6 concentration was increased on day 7 but was lower compared with X-rays at later times. C-ion effects on normal human skin fibroblasts seemed to be harmful in comparison with X-rays as they produce late DNA damage, LPO products and protein carbonyls, and as they decrease antioxidant defences. Mechanisms leading to this discrepancy between the two types of radiation should be investigated.

Oxidative stress and micronutrient therapy in malaria: an in vivo study in Plasmodium berghei infected mice

Free radical production from oxidative stress induced by malaria infection plays a major role in the pathogenesis of malaria. However, the use of agents with antioxidant activity may interfere with malaria progression. The study involves an in vivo evaluation of the role of some antioxidant micronutrients in the modulation of malaria infection. Rodent malaria model using Plasmodium berghei NK-65 strain (chloroquine sensitive) was used for the study. Forty five mice of either sex weighing 20.05 +/- 0.02 g were procured for the study. Forty mice were inoculated intraperitoneally with 1 x 10(7) million Plasmodium berghei infected erythrocyte and were administered with 0.2 mL of distilled water, 0.2 mL of vehicle; Tween 80 (control and vehicle group), chloroquine 25 mg kg(-1) and artesunate 4 mg kg(-1) (standard drug group), vitamin A 60 mg kg(-1), vitamin E 100 mg kg(-1), selenium 1 mg kg(-1), zinc 100 mg kg(-1) (test group F, G, H and I, respectively) 72 hours post inoculation. Antioxidant micronutrients demonstrated significant (p < 0.05) schizonticidal activity when compared with negative control during the 4 day curative test. Erythrocyte membrane disability was most markedly elevated in the tween 80 group (426.15%), followed closely by the chloroquine (373.85%) treated group and artesunate group (329.23%) and least in the zinc treated group (32.31%). There was no significant (p > 0.05) difference in MCFI values (0.115 +/- 0.002; 0.114 +/- 0.002 g dL(-1)) between vitamin A treated group and selenium treated group respectively. However, this was significant (p < 0.05) between the micronutrient treated groups and the control (negative, positive and vehicle). Conclusively, antioxidant micronutrients have antimalarial activity which may be due potentiation of erythrocyte membrane stabilization.

Study of antioxidative effects and anti-inflammatory effects in mice due to low-dose X-irradiation or radon inhalation

Low-dose irradiation induces various stimulating effects, especially activation of the biological defense system including antioxidative and immune functions. Oxidative stress induced by reactive oxygen species (ROS) can cause cell damage and death and can induce many types of diseases. This paper reviews new insights into inhibition of ROS-related diseases with low-dose irradiation or radon inhalation. X-irradiation (0.5 Gy) before or after carbon tetrachloride (CCl4) treatment inhibits hepatopathy in mice. X-irradiation (0.5 Gy) before ischemia-reperfusion injury or cold-induced brain injury also inhibits edema. These findings suggest that low-dose X-irradiation has antioxidative effects due to blocking the damage induced by free radicals or ROS. Moreover, radon inhalation increases superoxide dismutase activity in many organs and inhibits CCl4-induced hepatic and renal damage and streptozotocin-induced type I diabetes. These findings suggest that radon inhalation also has antioxidative effects. This antioxidative effect against CCl4-induced hepatopathy is comparable to treatment with ascorbic acid (vitamin C) at a dose of 500 mg/kg weight, or α-tocopherol (vitamin E) treatment at a dose of 300 mg/kg weight, and is due to activation of antioxidative functions. In addition, radon inhalation inhibits carrageenan-induced inflammatory paw edema, suggesting that radon inhalation has anti-inflammatory effects. Furthermore, radon inhalation inhibits formalin-induced inflammatory pain and chronic constriction injury-induced neuropathic pain, suggesting that radon inhalation relieves pain. Thus, low-dose irradiation very likely activates the defense systems in the body, and therefore, contributes to preventing or reducing ROS-related injuries, which are thought to involve peroxidation.

Mitigating effects of L-selenomethionine on low-dose iron ion radiation-induced changes in gene expression associated with cellular stress

Ionizing radiation associated with highly energetic and charged heavy (HZE) particles poses a danger to astronauts during space travel. The aim of the present study was to evaluate the patterns of gene expression associated with cellular exposure to low-dose iron ion irradiation, in the presence and absence of L-selenomethionine (SeM). Human thyroid epithelial cells (HTori-3) were exposed to low-dose iron ion (1 GeV/n) irradiation at 10 or 20 cGy with or without SeM pretreatment. The cells were harvested 6 and 16 h post-irradiation and analyzed by the Affymetrix U133Av2 gene chip arrays. Genes exhibiting a 1.5-fold expression cut-off and 5% false discovery rate (FDR) were considered statistically significant and subsequently analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) for pathway analysis. Representative genes were further validated by real-time RT-PCR. Even at low doses of radiation from iron ions, global genome profiling of the irradiated cells revealed the upregulation of genes associated with the activation of stress-related signaling pathways (ubiquitin-mediated proteolysis, p53 signaling, cell cycle and apoptosis), which occurred in a dose-dependent manner. A 24-h pretreatment with SeM was shown to reduce the radiation effects by mitigating stress-related signaling pathways and downregulating certain genes associated with cell adhesion. The mechanism by which SeM prevents radiation-induced transformation in vitro may involve the suppression of the expression of genes associated with stress-related signaling and certain cell adhesion events.

Effect of antioxidants on X-ray-induced γ-H2AX foci in human blood lymphocytes: preliminary observations

PURPOSE

To investigate the effect of a radioprotective oral agent containing a formulation of antioxidants and glutathione-elevating compounds on the extent of x-ray-induced γ-H2AX foci formation.

MATERIALS AND METHODS

The study was approved by local ethics committee and informed consent was obtained from each subject. In vitro experiments with blood lymphocytes of 25 healthy volunteers were performed without antioxidants and with antioxidants added either before or immediately after irradiation (10 mGy). For in vivo/in vitro tests, blood samples were obtained before, 15, 30, and 60 minutes (n=17) after, and 2, 3, and 5 hours (n=11) after oral ingestion of antioxidant pills and were irradiated (10 mGy). DNA double-strand breaks (DSBs) were quantified in isolated lymphocytes 5 minutes (in vitro and in vivo/in vitro) and 15 minutes (in vitro) after irradiation by enumerating γ-H2AX foci. To validate the data, additional in vitro experiments with use of 53BP1 as another independent marker for DSBs were performed. Nonirradiated samples served as controls. Statistical analyses were performed by using Wilcoxon rank-sum tests (in vitro), repeated-measures test, and Dunnett test (in vivo/in vitro).

RESULTS

In the in vitro experiments, 15-minute preincubation with antioxidants significantly reduced mean γ-H2AX foci levels by 23% (P<.0001), whereas addition of antioxidants immediately after irradiation did not lead to a reduction of x-ray-induced foci (P=.6905). Mean 53BP1 foci were also reduced by preincubation with the radioprotectant. In the in vivo/in vitro tests, oral pretreatment with antioxidants also led to a significant reduction of γ-H2AX foci formation; administration 60 minutes before irradiation resulted in a mean foci reduction of 58% (P<.0001).

CONCLUSION

The tested formulation of antioxidants significantly reduced formation of γ-H2AX and 53BP1 foci after irradiation at a radiologic radiation dose typical for computed tomographic imaging; administration 60 minutes prior to irradiation seems to be appropriate and leads to a significant reduction in foci.

In vitro and in vivo percutaneous absorption of seleno-L-methionine, an antioxidant agent, and other selenium species

AIM

To investigate the in vitro and in vivo percutaneous absorption of seleno-L-methionine (Se-L-M), an ultraviolet (UV)-protecting agent, from aqueous solutions.

METHODS

Aqueous solutions of Se-L-M were prepared in pH 4, 8, and 10.8 buffers. The pH 8 buffer contained 30% glycerol, propylene glycol (PG) and polyethylene glycol (PEG) 400. The in vitro skin permeation of Se-L-M via porcine skin and nude mouse skin was measured and compared using Franz diffusion cells. The in vivo skin tolerance study was performed, which examined transepidermal water loss (TEWL), skin pH and erythema.

RESULTS

In the excised porcine skin, the flux was 0.1, 11.4 and 8.2 μg·cm(-2)·h(-1) for the pH 4, 8, and 10.8 buffers, respectively. A linear correlation between the flux and skin deposition was determined. According to permeation across skin with different treatments (stripping, delipidation, and ethanol treatments), it was determined that the intracellular route comprised the predominant pathway for Se-L-M permeation from pH 8 buffer. Aqueous solutions of seleno-DL-methionine (Se-DL-M), selenium sulfide and selenium-containing quantum dot nanoparticles were also used as donor systems. The DL form showed a lower flux (7.0 vs 11.4 μg·cm(-2)·h(-1)) and skin uptake (23.4 vs 47.3 μg/g) as compared to the L form, indicating stereoselective permeation of this compound. There was no or only negligible permeation of selenium sulfide and quantum dots into and across the skin. With in vivo topical application for 4 and 8 h, the skin deposition of Se-L-M was about 7 μg/g, and values were comparable to each other. The topical application of Se-L-M for up to 5 d did not caused apparent skin irritation. However, slight inflammation of the dermis was noted according to the histopathological examination.

CONCLUSION

Se-L-M was readily absorbed by the skin in both the in vitro and in vivo experiments. The established profiles of Se-L-M skin absorption will be helpful in developing topical products of this compound.

Suppression of the later stages of radiation-induced carcinogenesis by antioxidant dietary formulations

We have previously reported data from a long-term carcinogenesis study indicating that dietary antioxidant supplements can suppress radiation-induced malignant lymphoma and harderian gland tumors induced by space radiations (specifically, 1 GeV/n iron ions or protons) in CBA/J mice. Two different antioxidant dietary supplements were used in these studies: a supplement containing a mixture of antioxidant agents [l-selenomethionine (SeM), N-acetyl cysteine (NAC), ascorbic acid, co-enzyme Q10, α-lipoic acid and vitamin E succinate], termed the AOX supplement, and another supplement known as Bowman-Birk Inhibitor Concentrate (BBIC). In the present report, the results from the earlier analysis of the harderian gland data from the published long-term animal study have been combined with new data derived from the same long-term animal study. In the earlier analysis, harderian glands were removed from animals exhibiting abnormalities (e.g. visibly swollen areas) around the eyes at the time of euthanasia or death in the long-term animal study. Abnormalities around the eyes were usually due to the development of tumors in the harderian glands of these mice. The new data presented here focused on the histopathological results obtained from analyses of the harderian glands of mice that did not have visible abnormalities around the eyes at the time of necropsy in the long-term animal study. In this paper, the original published data and the new data have been combined to provide a more complete evaluation of the harderian glands from animals in the long-term carcinogenesis study, with all available harderian glands from the animals processed and prepared for histopathological evaluation. The results indicate that, although dietary antioxidant supplements suppressed harderian gland tumors in a statistically significant fashion when all glands were analyzed, the antioxidant diets were less effective at suppressing the incidence of all harderian gland tumors than they were at suppressing the incidence of large harderian gland tumors (>2 mm) observed at animal necropsy. These results suggest that the dietary antioxidant formulations had major suppressive effects in the later stages of radiation-induced carcinogenesis in vivo. It is hypothesized that the dietary antioxidant formulations prevented the early-stage neoplastic growths from progressing to fully developed, malignant tumors. In addition, the antioxidant dietary formulations were very effective at preventing the development of proton- or iron-ion-induced malignant tumors, because, in contrast to irradiated controls, no malignant tumors were observed in the irradiated animals maintained on either of the dietary antioxidant diets.

Antioxidant dietary supplementation in mice exposed to proton radiation attenuates expression of programmed cell death-associated genes

Dietary antioxidants have radioprotective effects after ionizing radiation exposure that limit hematopoietic cell depletion. We sought to determine the mechanism of proton-induced hematopoietic cell death in animals receiving a moderate dose of whole-body proton radiation. In addition, animals were maintained on diets supplemented with or without dietary antioxidants. In the presence of the dietary antioxidants, total bone marrow mRNA and protein expression of apoptosis-related genes were decreased compared to the expression profiles in the irradiated mice not receiving the antioxidant formulation. These data confirm high-energy proton-induced gene expression of classical apoptosis markers including BAX, caspase-3 and PARP-1. Antioxidant supplementation resulted in decreased expression of these genes in addition to increased protein expression of the anti-apoptosis markers Bcl2 and Bcl-xL. In conclusion, oral supplementation with antioxidants appears to be an effective approach for radioprotection against hematopoietic cell death.

In vivo and in vitro models of ionizing radiation to the vocal folds

BACKGROUND

Radiation therapy (RT) to the head and neck often results in damage to the vocal folds (VF) and surrounding structures. Characterization and treatment of these sequelae is limited, likely due to the lack of experimental models.

METHODS

Larynges from rats exposed to 2 fractionation schedules (40 Gy total) were analyzed histologically. In vitro, reactive oxygen species (ROS) synthesis, and transcription of select genes associated with ROS, inflammation, and fibrosis were examined in VF fibroblasts after single-dose radiation.

RESULTS

Although radiation-induced histologic alterations are made to VF architecture, 1 fractionation schedule was accompanied by significant morbidity and mortality. In vitro, radiation increased ROS synthesis and inflammatory and profibrotic gene expression.

CONCLUSION

Our data suggest that hyperfractionated RT is more tolerable. Utilizing this model, RT-induced histologic aberrations are made to the VF mucosa. In addition, a relationship between radiation, ROS, and inflammatory and fibrotic gene expression was observed in vitro.

Dietary supplements reduce the cataractogenic potential of proton and HZE-particle radiation in mice

Abstract The present study was undertaken to investigate the ability of dietary supplements to reduce the formation and severity of cataracts in mice irradiated with high-energy protons or iron ions, which are important components of the radiation encountered by astronauts during space travel. The mice were exposed to proton or iron-ion radiation and fed with a control diet or diets supplemented with the soybean-derived protease inhibitor, Bowman-Birk inhibitor (BBI), in the form of BBI Concentrate (BBIC) or an antioxidant formulation [containing l-selenomethionine (SeM), N-acetyl cysteine (NAC), ascorbic acid, co-enzyme Q10, alpha-lipoic acid and vitamin E succinate] both before and after the radiation exposure. At approximately 2 years after the radiation exposure, the animals were killed humanely and lenses were harvested and characterized using an established classification system that assigns discrete scores based on the severity of the lens opacifications. The results showed that exposure to 1 GeV/nucleon proton (3 Gy) or iron-ion (50 cGy) radiation significantly increased the cataract prevalence and severity in CBA/J mice to levels above the baseline levels of age-induced cataract formation in this mouse strain. Treatment with BBIC or the antioxidant formulation significantly reduced the prevalence and severity of the lens opacifications in the mice exposed to iron-ion radiation. Treatment with BBIC or the antioxidant formulation also decreased the severity of the lens opacifications in the mice exposed to proton radiation; however, the decrease did not reach statistical significance. These results indicate that BBIC and the antioxidant formulation evaluated in this study could be useful for protecting astronauts against space radiation-induced cataracts during or after long-term manned space missions.

Factors that modify radiation-induced carcinogenesis

It is known that numerous factors can influence radiation carcinogenesis in animals; these factors include the specific characteristics of the radiation (radiation type and dose, dose-rate, dose-fractionation, dose distribution, etc.) as well as many other contributing elements that are not specific to the radiation exposure, such as animal genetic characteristics and age, the environment of the animal, dietary factors and whether specific modifying agents for radiation carcinogenesis have been utilized in the studies. This overview focuses on the modifying factors for radiation carcinogenesis, in both in vivo and in vitro systems, and includes a discussion of agents that enhance (e.g., promoting agents) or suppress (e.g., cancer preventive agents) radiation-induced carcinogenesis. The agents that enhance or suppress radiation carcinogenesis in experimental model systems have been shown to lead to effects equally as large as other known modifying factors for radiation-induced carcinogenesis (e.g., dose-rate, dose-fractionation, linear energy transfer). It is known that dietary factors play an important role in determining the yields of radiation-induced cancers in animal model systems, and it is likely that they also influence radiation-induced cancer risks in human populations.

Radioprotective effects of manganese-containing superoxide dismutase mimics on ataxia-telangiectasia cells

We tested several classes of antioxidant manganese compounds for radioprotective effects using human lymphoblastoid cells: six porphyrins, three salens, and two cyclic polyamines. Radioprotection was evaluated by seven assays: XTT, annexin V and propidium iodide flow cytometry analysis, gamma-H2AX immunofluorescence, the neutral comet assay, dichlorofluorescein and dihydroethidium staining, resazurin, and colony survival assay. Two compounds were most effective in protecting wild-type and A-T cells against radiation-induced damage: MnMx-2-PyP-Calbio (a mixture of differently N-methylated MnT-2-PyP+ from Calbiochem) and MnTnHex-2-PyP. MnTnHex-2-PyP protected WT cells against radiation-induced apoptosis by 58% (p = 0.04), using XTT, and A-T cells by 39% (p = 0.01), using annexin V and propidium iodide staining. MnTnHex-2-PyP protected WT cells against DNA damage by 57% (p = 0.005), using gamma-H2AX immunofluorescence, and by 30% (p < 0.01), using neutral comet assay. MnTnHex-2-PyP is more lipophilic than MnMx-2-PyP-Calbio and is also >10-fold more SOD-active; consequently it is >50-fold more potent as a radioprotectant, as supported by six of the tests employed in this study. Thus, lipophilicity and antioxidant potency correlated with the magnitude of the beneficial radioprotectant effects observed. Our results identify a new class of porphyrinic radioprotectants for the general and radiosensitive populations and may also provide a new option for treating A-T patients.

N-acetyl cysteine protects against ionizing radiation-induced DNA damage but not against cell killing in yeast and mammals

Ionizing radiation (IR) induces DNA strand breaks leading to cell death or deleterious genome rearrangements. In the present study, we examined the role of N-acetyl-L-cysteine (NAC), a clinically proven safe agent, for it's ability to protect against gamma-ray-induced DNA strand breaks and/or DNA deletions in yeast and mammals. In the yeast Saccharomyces cerevisiae, DNA deletions were scored by reversion to histidine prototrophy. Human lymphoblastoid cells were examined for the frequency of gamma-H2AX foci formation, indicative of DNA double strand break formation. DNA strand breaks were also measured in mouse peripheral blood by the alkaline comet assay. In yeast, NAC reduced the frequency of IR-induced DNA deletions. However, NAC did not protect against cell death. NAC also reduced gamma-H2AX foci formation in human lymphoblastoid cells but had no protective effect in the colony survival assay. NAC administration via drinking water fully protected against DNA strand breaks in mice whole-body irradiated with 1Gy but not with 4Gy. NAC treatment in the absence of irradiation was not genotoxic. These data suggest that, given the safety and efficacy of NAC in humans, NAC may be useful in radiation therapy to prevent radiation-mediated genotoxicity, but does not interfere with efficient cancer cell killing.

Effects of dietary antioxidant supplementation on the development of malignant lymphoma and other neoplastic lesions in mice exposed to proton or iron-ion radiation

Malignancy is considered to be a particular risk associated with exposure to the types of ionizing radiation encountered during extended space flight. In the present study, two dietary preparations were evaluated for their ability to prevent carcinogenesis in CBA mice exposed to different forms of space radiation: protons and highly energetic heavy particles (HZE particles). One preparation contained a mixture of antioxidant agents. The other contained the soybean-derived Bowman-Birk protease inhibitor (BBI), used in the form of BBI Concentrate (BBIC). The major finding was that there was a reduced risk of developing malignant lymphoma in animals exposed to space radiation and maintained on diets containing the antioxidant formulation or BBIC compared to the irradiated animals maintained on the control diet. In addition, the two different dietary countermeasures also reduced the yields of a variety of different rare tumor types observed in the animals exposed to space radiation. These results suggest that dietary supplements could be useful in the prevention of malignancies and other neoplastic lesions developing from exposure to space radiation.

Dietary antioxidants protect hematopoietic cells and improve animal survival after total-body irradiation

The purpose of this study was to determine whether a dietary supplement consisting of L-selenomethionine, vitamin C, vitamin E succinate, alpha-lipoic acid and N-acetyl cysteine could improve the survival of mice after total-body irradiation. Antioxidants significantly increased the 30-day survival of mice after exposure to a potentially lethal dose of X rays when given prior to or after animal irradiation. Pretreatment of animals with antioxidants resulted in significantly higher total white blood cell and neutrophil counts in peripheral blood at 4 and 24 h after 1 Gy and 8 Gy. Antioxidants were effective in preventing peripheral lymphopenia only after low-dose irradiation. Antioxidant supplementation was also associated with increased bone marrow cell counts after irradiation. Supplementation with antioxidants was associated with increased Bcl2 and decreased Bax, caspase 9 and TGF-beta1 mRNA expression in the bone marrow after irradiation. Maintenance of the antioxidant diet was associated with improved recovery of the bone marrow after sublethal or potentially lethal irradiation. Taken together, oral supplementation with antioxidants appears to be an effective approach for radioprotection of hematopoietic cells and improvement of animal survival, and modulation of apoptosis is implicated as a mechanism for the radioprotection of the hematopoietic system by antioxidants.

Cellular antioxidant activity (CAA) assay for assessing antioxidants, foods, and dietary supplements

A cellular antioxidant activity (CAA) assay for quantifying the antioxidant activity of phytochemicals, food extracts, and dietary supplements has been developed. Dichlorofluorescin is a probe that is trapped within cells and is easily oxidized to fluorescent dichlorofluorescein (DCF). The method measures the ability of compounds to prevent the formation of DCF by 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP)-generated peroxyl radicals in human hepatocarcinoma HepG2 cells. The decrease in cellular fluorescence when compared to the control cells indicates the antioxidant capacity of the compounds. The antioxidant activities of selected phytochemicals and fruit extracts were evaluated using the CAA assay, and the results were expressed in micromoles of quercetin equivalents per 100 micromol of phytochemical or micromoles of quercetin equivalents per 100 g of fresh fruit. Quercetin had the highest CAA value, followed by kaempferol, epigallocatechin gallate (EGCG), myricetin, and luteolin among the pure compounds tested. Among the selected fruits tested, blueberry had the highest CAA value, followed by cranberry > apple = red grape > green grape. The CAA assay is a more biologically relevant method than the popular chemistry antioxidant activity assays because it accounts for some aspects of uptake, metabolism, and location of antioxidant compounds within cells.

Countermeasures against space radiation induced oxidative stress in mice

Of particular concern for the health of astronauts during space travel is radiation from protons and high atomic number (Z), high energy particles (HZE particles). Space radiation is known to induce oxidative stress in astronauts after extended space flight. In the present study, the total antioxidant status was used as a biomarker to evaluate oxidative stress induced by proton and HZE particle radiation in the plasma of CBA mice and the protective effect of dietary supplement agents. The results indicate that exposure to proton and HZE particle radiation significantly decreased the plasma level of total antioxidants in the irradiated CBA mice. Dietary supplementation with L: -selenomethionine (SeM) or a combination of selected antioxidant agents (which included SeM) could partially or completely prevent the decrease in the total antioxidant status in the plasma of animals exposed to proton or HZE particle radiation. These findings suggest that exposure to space radiation may compromise the capacity of the host antioxidant defense system; this adverse biological effect can be prevented at least partially by dietary supplementation with agents expected to have effects on antioxidant activities.

Protection against adverse biological effects induced by space radiation by the Bowman-Birk inhibitor and antioxidants

This study was undertaken to evaluate the protective effects of the soybean-derived Bowman-Birk inhibitor (BBI), BBI concentrate (BBIC) and/or antioxidants against the adverse biological effects induced by space radiation in cultured human epithelial cells. The effects of BBI, BBIC and a combination of ascorbic acid, co-enzyme Q10, L-selenomethionine (SeM) and vitamin E succinate on proton and HZE-particle [high-energy (high E) nuclei of heavier (high atomic number, Z) elements] radiation-induced cytotoxicity in MCF10 human breast epithelial cells and a phenotypic change associated with transformation in HTori-3 human thyroid epithelial cells were assessed with a clonogenic survival assay and a soft agar colony formation assay. The results demonstrate that BBIC and antioxidants are effective in protecting against space radiation-induced cytotoxicity in MCF10 cells and BBI, BBIC and antioxidants are effective in protecting against a space radiation-induced phenotypic change associated with transformation of HTori-3 cells.