Gamma Radiation-induced Damage Research Articles

Black Grape Juice Protects Spleen from Lipid Oxidation Induced by Gamma Radiation in Rats

ABSTRACT This study evaluated the effects of black grape juice (BGJ) against gamma radiation-induced damage in rats. Rats were exposed (PI) or not (PNI) to radiation and BGJ (2 mL/Kg of body weight) was administrated to irradiated animals (SI) and to nonirradiated animals (SNI). Blood was collected at different time points after irradiation for blood cells counts. The spleen of the animals was removed for weight, lipid peroxidation (LPO) and antioxidant defenses estimation. Blood cell count decreased, whereas LPO and catalase activity increased in spleen along with a decrease in the organ weight after irradiation. Despite the lack of protective effect on hematological parameters and catalase activity, BGJ attenuated LPO induced by gamma radiation. This protective effect seems to be related to the phenolic compounds found in BGJ, such as resveratrol, quercetin and rutin. We demonstrated that BGJ plays a beneficial role in damage caused by gamma radiation by preventing spleen LPO. PRACTICAL APPLICATIONS Grape products, such as black grape juice (BGJ), and their polyphenol compounds have several properties that can be useful in prevention and treatment of many conditions. One of these properties is the antioxidant capacity, which makes of phenolic compounds, such as resveratrol, quercetin and rutin, good exogenous scavengers of free radicals. The present study demonstrates that BGJ exhibits a radiomodifier potential against gamma radiation by exerting antioxidant effects and, hence, it can be used as a valuable agent for managing radiation exposure.

Radioprotection by Macerated Extract of Nigella sativa in Normal Tissues of Fibrosarcoma Bearing Mice.

The current study was undertaken to study the effect of a macerated extract of Nigella sativa seeds in normal as well as in tumour bearing mice against gamma radiation-induced cellular damage to normal tissues. This was done to mimic the clinical setting where in, normal tissues of cancer patients undergoing radiotherapy are exposed to the deleterious effects of radiation. The protection of cellular DNA was analysed in peripheral blood leucocytes of whole body irradiated mice following pretreatment with macerated extract of Nigella sativa seeds (100 mg/kg), using alkaline comet assay, and also estimating biochemical and blood parameters such as levels of antioxidant enzymes superoxide dismutase and catalase, thiobarbituric acid reactive substances and protein oxidation in organs such as spleen, liver, brain and intestine haemoglobin and total leucocyte count, respectively. The results showed that the macerated extract of Nigella sativa seeds protected the liver, spleen, brain and intestines both in normal as well as tumour bearing mice. This study concludes that macerated extract of Nigella sativa seeds has protective effects against radiation-induced damage and biochemical alterations which could be attributed to the ability to scavenge free radicals and its antioxidant properties. Hence macerated extract of Nigella sativa seeds, could be used in combination with radiation to protect against oxidative stress in normal tissues and improving the quality of life of cancer patients by mitigating unwanted side effects of radiation in normal tissues.

Protection of rat chromosomes by melatonin against gamma radiation-induced damage

The aim of this study was to investigate the protective effect of melatonin (2.5 mg/kg/day, given to rats five times by intra-peritoneal injection) against damage in bone-marrow chromosomes induced by a single dose of gamma radiation (4.0 Gy whole-body irradiation; WBI). Ninety-six male albino rats were divided into four equal groups of 24 rats each. They were designated as I—non-irradiated, non-treated control rats, II—non-irradiated rats treated with melatonin for five successive days, III—whole-body gamma-irradiated rats and IV—rats injected with melatonin daily for five successive days, then subjected to whole-body gamma irradiation 2 h after the final melatonin injection. Six rats from each group were sacrificed at days 1, 3, 7 and 10 following treatment and/or irradiation and their bone marrows were flushed out for micronuclei scoring and chromosomal analysis. WBI resulted in significant elevations in bone-marrow polychromatic erythrocytes containing micronuclei in their cytoplasm, and caused a significant decrease in the mitotic index of bone-marrow cells; in addition, there was a significant increase in the frequency of aberrant bone-marrow cells and in the different types of structural chromosomal aberration. Melatonin injection prior to WBI significantly reduced the mean frequencies of micro-nucleated polychromatic erythrocytes and of aberrant cells, as well as the incidence of structural chromosomal aberrations in bone-marrow cells; it also caused a highly significant elevation in the value of the mitotic index of bone-marrow cells. This investigation clarifies the protective and/or ameliorative role played by melatonin against deleterious effects of gamma radiation.

Radiation-induced micronucleus formation and DNA damage in human lymphocytes and their prevention by antioxidant thiols

Thiol family of antioxidants has been considered to be the most effective class of radio protective agents. Present study reports a comparative evaluation of antioxidant thiols, namely N-acetyl cysteine (NAC), glutathione (GSH) and thioproline (TP), on gamma radiation-induced damage to human lymphocytes DNA as assessed by micronucleus (MN) formation and comet assay parameters. Pretreatment of cells with NAC, GSH and TP showed significant protection against DNA damage and MN frequency in irradiated lymphocytes (2–4 Gy). The magnitude of DNA damage protection was found to be concentration dependent (100–300 μM) which followed the order GSH > NAC > TP. Further, antioxidant thiols mediated protection against DNA damage in irradiated lymphocyte showed significant correlation with their ability to decrease intracellular ROS but not to the increase in intracellular GSH. Experiments on the effect of antioxidant thiols on plasmid DNA irradiated under cell free aqueous conditions showed that NAC exerts greater protection than GSH against radiation damage. TP showed similar responses in cellular and plasmid DNA. Greater protection of plasmid DNA by NAC is ascribable to its more potential hydrogen donor ability as revealed by radical chromogen 2,2-diphenyl-1-picrylhydrazyl (DPPH) photometric assay. Thus, present study indicated that radioprotection of lymphocytes DNA by antioxidant thiols are closely correlated to the reduction of cellular oxidative stress, which seems to involve multiple mechanisms.

Radioprotective effect of sulfasalazine on mouse bone marrow chromosomes

Sulfasalazine (SAZ), a prescribed drug for inflammatory bowel disease, is a potent scavenger of reactive oxygen species. The present study was undertaken to ascertain its ability to protect against gamma radiation-induced damage. Acute toxicity of the drug was studied taking 24-h, 72-h and 30-day mortality after a single intraperitoneal injection of 400-1200 mg/kg body weight (b.wt.) of the drug. The drug LD(50) for 24- and 72-h/30-day survival were found to be 933 and 676 mg/kg b.wt., respectively. The optimum time of drug administration and drug dose-dependent effect on in vivo radiation protection of bone marrow chromosomes was studied in mice. Injection of 30-180 mg/kg SAZ 30 min before gamma irradiation (RT) with 4 Gy produced a significant dose-dependent reduction in the RT-induced percent aberrant metaphases and in the frequency of micronucleated erythrocytes at 24 h after exposure, with a corresponding decrease in the different types of aberrations. The optimum dose for protection without drug toxicity was 120 mg/kg b.wt. At this dose, SAZ produced >60% reduction in the RT-induced percent aberrant metaphases and micronucleated erythrocytes. SAZ also produced a significant increase in the ratio of polychromatic erythrocytes to normochromatic erythrocytes from that of irradiated control. Injection of 120 mg/kg of the drug 60 or 30 min before or within 15 min after 4 Gy whole-body RT resulted in a significant decrease in the percent of aberrant metaphases and in the frequency of micronucleated erythrocytes at 24 h post-irradiation; the maximum effect was seen when the drug was administered 30 min before irradiation. These results show that SAZ protect mice against RT-induced chromosomal damage and cell cycle progression delay. SAZ also protected plasmid DNA (pGEM-7Zf) against Fenton's reactant-induced breaks, suggesting free radical scavenging as one of the possible mechanism for radiation protection.

Quercetin ameliorates gamma radiation-induced DNA damage and biochemical changes in human peripheral blood lymphocytes

We investigated the radioprotective efficacy of quercetin (QN), a naturally occurring flavonoid against gamma radiation-induced damage in human peripheral blood lymphocytes and plasmid DNA. In plasmid study, QN at different concentrations (3, 6, 12, 24 and 48 μM) were pre-incubated with plasmid DNA for 1 h followed by exposure of 6 Gy radiation. Among all concentrations of QN used, 24 μM showed optimum radioprotective potential. To establish the most effective protective concentration of QN in lymphocytes, the cells were pre-incubated with 3, 6, 12, 24 and 48 μM of QN for 30 min and then exposed to 4 Gy γ-radiation. The concentration-dependent effects of QN were evaluated by scoring micronuclei (MN) frequencies. The results showed that QN decreased the MN frequencies dose dependently, but the effect was more pronounced at 24 μM. Thus, 24 μM of QN was selected as the optimum concentration and was further used to evaluate its radioprotective effect in lymphocytes. For that a separate experiment was carried out, in which lymphocytes were incubated with QN (24 μM) for 30 min and exposed to different doses of radiation (1, 2, 3 and 4 Gy). Genetic damage (MN, dicentric aberration and comet attributes) and biochemical changes were measured to evaluate the effect of QN on γ-radiations (1–4 Gy). Radiation exposed showed significant increases in the genetic damage and thiobarbituric acid reactive substances (TBARS) accompanied by a significant decrease in the antioxidant status. QN pretreatment significantly decreased the genetic damage and TBARS and improved antioxidant status through its antioxidant potential. Altogether, our findings encourage further mechanistic and in vivo studies to investigate radioprotective efficacy of QN.

Studies on the Protective Effects of Boerhaavia diffusa L. Against Gamma Radiation—Induced Damage in Mice

The radioprotective effect of the hydro-alcoholic extract of Boerhaavia diffusa was studied using the in vivo mice model. The sublethally irradiated mice (600 rads, single dose) were treated intraperitoneally with 20 mg/kg of the extract. The animals were sacrificed at different time periods after the whole-body radiation. The most affected tissues--bone marrow and intestine--were considerably protected by the intraperitoneal administration of B. diffusa as estimated by bone marrow cellularity, maturing monocytes, and intestinal glutathione. Total white blood cell count was lowered drastically after radiation exposure (ninth day, 1500+/-500 cells/ mm(3)). When the animals were exposed to radiation and treated with B. diffusa, the total white blood cell count was lowered only to 4000+/-400 cells/mm(3) on the third day, and it reached an almost normal level (6250+/-470 cells/mm(3)) by the ninth day. The elevated level of serum and liver alkaline phosphatase after radiation exposure was reduced in the B. diffusa-treated group. The serum and liver glutamate pyruvate transferase, which were elevated after radiation exposure, were also reduced by treatment with B. diffusa compared to the control. The lipid peroxidation level also increased in the irradiated animals both in the liver and serum, but in B. diffusa-treated animals, there was a significant reduction in lipid peroxidation levels. The agarose gel electrophoresis of DNA isolated from bone marrow of mice exposed to gamma radiation showed heavy damage that was reduced by treatment with B. diffusa. These results are indicative of the radioprotective effect of the whole-plant extract of B. diffusa.

Protection of the Hemopoietic System byPodophyllum hexandrumagainst Gamma Radiation-Induced Damage

A semi-purified extract of low-altitude Podophyllum hexandrum (REC-2001) containing a relatively low content of podophyllotoxin (3.25 %) exhibited potent antioxidant ability in lipid media (at 1000 microg/mLagainst 0.25 kGy) and significant (p < 0.05) hydroxyl ion scavenging potential (78.83 % at 500 microg/mL). In vitro investigations revealed the ability of REC-2001 to significantly (p < 0.05) reduce radiation-induced hemolysis (2 microg/mL; 46.184 %) and nitric oxide scavenging levels (IC (50): 792 +/- 1.25 microg/mL). Protection of the hemopoietic system of Strain 'A' mice administered 20 mg/kg BW REC-2001 30 min prior to lethal irradiation (10 Gy) was recorded and was mediated by free radical scavenging and lowering of lipid oxidation. Further studies investigating the effects of REC-2001 on stem cell modulation are warranted.

The effects of thyroid scintigraphy studies on oxidative damage in patients

The majority of radiation injury in cells depends on oxidative stress. Irradiation and absorbed doses, duration of the irradiation and the susceptibility of the tissue against radiation are the factors that cause variations on living cells. The aim of this study was to investigate gamma radiation-induced oxidative damage in erythrocytes after thyroid scintigraphy with Tc-99m pertechnetate. Fifteen patients (8 women and 7 men) who performed thyroid scintigraphy with Tc-99m pertechnetate were included in this study. The median age was 52 +/- 8 years (range 33-65). The blood samples were taken from patients just before, 1 hour after and three hours after injection of radiopharmaceutical. Malondialdehyde (MDA) and antioxidant enzymes such as glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) levels were measured to evaluate the gamma radiation induced oxidative damage. No difference was detected in any final measurement activities of erythrocyte antioxidant enzyme such as SOD and GPX in the direct comparison between the before and after injection of the radiopharmaceutical groups, except erythrocyte CAT activities measured 1 hour after and 3 hours after injection of the radiopharmaceutical (p < 0.05). MDA levels were decreased 1 hour after and 3 hours after injection of the radiopharmaceutical.

Protection of the Hematopoetic System byPodophyllum hexandrumagainst Gamma Radiation-Induced Damage

Protection of the Hematopoetic System by<i>Podophyllum hexandrum</i>against Gamma Radiation-Induced Damage

Radiation protection by Terminalia chebula: Some mechanistic aspects

Radioprotective ability of the aqueous extract of the fruit of Terminalia chebula (TCE) was evaluated for its antioxidant and radioprotective abilities. TCE (50 microg) was able to neutralise 1,1-diphenyl-2-picrylhydrazyl, a stable free radical by 92.9%. The free radical neutralizing ability of TCE was comparable to that of ascorbate (100 microM) 93.5% and gallic acid (100 microM) 91.5% and was higher than that of the diethyldithiocarbamate (200 microM) 55.4%, suggesting the free radical activity of TCE. TCE protected the plasmid DNA pBR322 from undergoing the radiation-induced strand breaks. Radiation damage converts the supercoiled form (ccc) of plasmid to open circular form (oc); the presence of TCE during radiation exposure protected the plasmid from undergoing these damages. The administration of TCE (80 mg/kg body weight, i.p.) prior to whole body irradiation of mice (4 Gy) resulted in a reduction of peroxidation of membrane lipids in the mice liver as well as a decrease in radiation-induced damage to DNA, as assayed by single-cell gel electrophoresis (comet assay). TCE also protected the human lymphocytes from undergoing the gamma radiation-induced damage to DNA exposed in vitro to 2 Gy gamma-radiation. These results suggest the radioprotective ability of TCE.

Analysis of gamma radiation-induced damage to plasmid DNA using dynamic size-sieving capillary electrophoresis

Bacterial plasmids and the chromosomal DNA of many organisms adopt naturally the negatively supercoiled conformation. Therefore, the irradiation of such plasmids could be used to model conformational changes of chromosomal DNA associated with externally-induced damage. We have applied dynamic size-sieving capillary electrophoresis (CE) to monitor the damage of three DNA plasmids, over an unprecedented base pair (bp) size range (2870–27 500 bp), upon exposure to γ-radiation (20–400 Gy). Predominantly, CE with UV absorbance detection in the absence of DNA intercalating dyes was employed to preclude undesirable, induced plasmid conformational changes. Plasmid samples and their enzymatic digestion products were analyzed using both CE and slab gel electrophoresis (SGE) in order to verify the conformation of sample components. Relative to SGE, CE analyses revealed more fine structural features of plasmid degradation.

Mechanisms of radiation-induced chromosome aberrations

We investigated the radioprotective efficacy of quercetin (QN), a naturally occurring flavonoid against gamma radiation-induced damage in human peripheral blood lymphocytes and plasmid DNA. In plasmid study, QN at different concentrations (3, 6, 12, 24 and 48 μM) were pre-incubated with plasmid DNA for 1 h followed by exposure of 6 Gy radiation. Among all concentrations of QN used, 24 μM showed optimum radioprotective potential. To establish the most effective protective concentration of QN in lymphocytes, the cells were pre-incubated with 3, 6, 12, 24 and 48 μM of QN for 30 min and then exposed to 4 Gy γ-radiation. The concentration-dependent effects of QN were evaluated by scoring micronuclei (MN) frequencies. The results showed that QN decreased the MN frequencies dose dependently, but the effect was more pronounced at 24 μM. Thus, 24 μM of QN was selected as the optimum concentration and was further used to evaluate its radioprotective effect in lymphocytes. For that a separate experiment was carried out, in which lymphocytes were incubated with QN (24 μM) for 30 min and exposed to different doses of radiation (1, 2, 3 and 4 Gy). Genetic damage (MN, dicentric aberration and comet attributes) and biochemical changes were measured to evaluate the effect of QN on γ-radiations (1–4 Gy). Radiation exposed showed significant increases in the genetic damage and thiobarbituric acid reactive substances (TBARS) accompanied by a significant decrease in the antioxidant status. QN pretreatment significantly decreased the genetic damage and TBARS and improved antioxidant status through its antioxidant potential. Altogether, our findings encourage further mechanistic and in vivo studies to investigate radioprotective efficacy of QN.

Effect of in vivo γ-irradiation on the binding of wheat germ agglutinin on lymphocyte plasma membranes

Using quantitative fluorimetry with fluoresceinated wheat germ agglutinin, we have been able to investigate in vivo gamma radiation-induced damage at the outer membrane level of rat splenic lymphocytes, namely damage to the glucosidic moieties of membrane glycoproteins and glycolipids. This paper demonstrates that below an irradiation level of 1 gray (Gy), removal of sialic acid is the major feature leading to new exposed specific binding sites for wheat germ agglutinin, since this lectin is specific for sialic acid and N- acetyl- D-glucosamine . Our studies also suggest that above 1 Gy of irradiation more internal damage occurs, since we observed a striking decrease in wheat germ agglutinin binding sites.

Repair of potential lethal radiation damage in γ-irradiated euglena cells

Unicellular alga Euglena gracilis has an ability to repair potential lethal 60Co gamma radiation-induced damage. The survival on agar after post-irradiation incubation increased by a factor of about 3 relative to that for no incubation.

Modification of High LET Radiation-induced Damage and Its Repair in Yeast by Hypoxia

The lethal response of a diploid yeast strain BZ34 to densely ionizing radiations from the reaction 10B(n, alpha)7 Li was studied. The values for relative biological effectiveness (r.b.e.) and oxygen enhancement ratio (o.e.r.) for this radiation compare favourably with the data obtained with charged particles on the same strain of yeast. Recovery from potentially lethal damage was also studied by post-irradiation holding under non-nutrient conditions. In order to understand the role of oxygen in the recovery process, the investigation covered the following treatment regimens: (a) aerobic irradiation and aerobic holding (A-A), (b) aerobic irradiation and hypoxic holding (A-H), (c) hypoxic irradiation and hypoxic holding (H-H) and (d) hypoxic irradiation and aerobic holding (H-A). It has been found that the presence of oxygen is essential for recovery from the damage induced by both gamma rays and high linear energy transfer (LET) radiations. The extent of recovery was larger for gamma-induced damage than for damage induced by high LET radiation (alpha + 7Li) for the A-A condition. In the H-H condition, while only a slight recovery was seen for gamma-induced damage, it was totally absent for high LET damage. For the modality A-H, it was found that there is not recovery from the sparsely ionising gamma radiation-induced damage. The implications of these results for the treatment of malignant tumours by radiotherapy are briefly discussed.