Protection of DNA and membrane from gamma radiation induced damage by gallic acid

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a naturally occurring plant phenol. In vitro and in vivo studies have shown that this phytochemical protected DNA and membranes against ionizing radiation. Rat liver microsomes and plasmid pBR322 DNA were exposed to various doses of gamma radiation in presence and absence of GA. Exposure of the microsomes to gamma radiation resulted in the formation of peroxides of membrane lipids measured as thiobarbituric acid reactive substances and presence of GA during irradiation prevented the formation of lipid peroxidation. Gamma irradiation of plasmid DNA resulted in induction of strand breaks in DNA resulting in disappearance of the supercoiled (ccc) form. Presence of GA during irradiation protected the DNA from undergoing the strand breaks. In in vivo studies it was found that whole body exposure of mice to gamma radiation (4 Gy) increased the formation of lipid peroxides in various tissues and damage to cellular DNA (as measured by alkaline comet assay) in peripheral blood leucocytes. Administration of GA to mice prior to whole body radiation exposure reduced the peroxidation of lipids and the damage to the cellular DNA indicating in vivo radiation protection of membranes and DNA by GA. (Mol Cell Biochem 278: 111–117, 2005)     

Protection against genotoxic damages following whole body gamma radiation exposure in mice by lipoic acid

Alpha-lipoic acid (LA) protected plasmid pBR 322 DNA, under in vitro conditions from gamma radiation induced strand breaks as evidenced by the prevention of the loss of supercoiled covalently closed circular form upon irradiation. It also protected the membrane lipids of liver homogenates from the oxidative damages. Whole body exposure of mice to gamma-radiation resulted in damage to cellular DNA in various tissues and administration of LA prior to the radiation exposure prevented the radiation induced DNA damage as assessed by alkaline comet assay. Administration of LA to mice prior to the radiation exposure also prevented induction of chromosomal damages in bone marrow cells and formation of micronuclei in blood reticulocytes. Thus taken together, LA a normal cellular constituent could be used as a radioprotector against whole body radiation exposure scenarios.     

Protection against radiation oxidative damage in mice by Triphala

Protection against whole body gamma-irradiation (WBI) of Swiss mice orally fed with Triphala (TPL), an Ayurvedic formulation, in terms of mortality of irradiated animals as well as DNA damage at cellular level has been investigated. It was found that radiation induced mortality was reduced by 60% in mice fed with TPL (1g/kg body weight/day) orally for 7 days prior to WBI at 7.5 Gy followed by post-irradiation feeding for 7 days. An increase in xanthine oxidoreductase activity and decrease in superoxide dismutase activity was observed in the intestine of mice exposed to WBI, which, however, reverted back to those levels of sham-irradiated controls, when animals were fed with TPL for 7 days prior to irradiation. These data have suggested the prevention of oxidative damage caused by whole body radiation exposure after feeding of animals with TPL. To further understand the mechanisms involved, the magnitude of DNA damage was studied by single cell gel electrophoresis (SCGE) in blood leukocytes and splenocytes obtained from either control animals or those fed with TPL for 7 days followed by irradiation. Compared to irradiated animals without administering TPL, the mean tail length was reduced about three-fold in blood leukocytes of animals fed with TPL prior to irradiation. Although, similar protection was observed in splenocytes of TPL fed animals, the magnitude of prevention of DNA damage was significantly higher than that observed in leukocytes. It has been concluded that TPL protected whole body irradiated mice and TPL induced protection was mediated through inhibition of oxidative damage in cells and organs. TPL seems to have potential to develop into a novel herbal radio-protector for practical applications.     

Protection by pantothenol and beta-carotene against liver damage produced by low-dose gamma radiation.

Rats were exposed to a total dose of 0.75 Gy of gamma radiation from a 60Co source, receiving three doses of 0.25 Gy at weekly intervals. During two days before each irradiation, the animals received daily intragastric doses of 26 mg pantothenol or 15 mg beta-carotene per kg body mass. The animals were killed after the third irradiation session, and their blood and livers were analyzed. As found previously (Slyshenkov, V.S., Omelyanchik, S.N., Moiseenok, A.G., Trebukhina, R.V. & Wojtczak, L. (1998) Free Radical Biol. Med. 24, 894-899), in livers of animals not supplied with either pantothenol or beta-carotene and killed one hour after the irradiation, a large accumulation of lipid peroxidation products, as conjugated dienes, ketotrienes and thiobarbituric acid-reactive substances, could be observed. The contents of CoA, pantothenic acid, total phospholipids, total glutathione and GSH/GSSG ratio were considerably decreased, whereas the NAD/NADH ratio was increased. All these effects were alleviated in animals supplied with beta-carotene and were completely abolished in animals supplied with pantothenol. In the present paper, we extended our observations of irradiation effects over a period of up to 7 days after the last irradiation session. We found that most of these changes, with the exception of GSH/GSSG ratio, disappeared spontaneously, whereas supplementation with beta-carotene shortened the time required for the normalization of biochemical parameters. In addition, we found that the activities of glutathione reductase, glutathione peroxidase, catalase and NADP-dependent malate (decarboxylating) dehydrogenase ('malic enzyme') in liver were also significantly decreased one hour after irradiation but returned to the normal level within 7 days. Little or no decrease in these activities, already 1 h after the irradiation, could be seen in animals supplemented with either beta-carotene or pantothenol. It is concluded that pantothenol is an excellent radioprotective agent against low-dose gamma radiation.     

Small-molecule inhibitor of p53 binding to mitochondria protects mice from gamma radiation

p53-dependent apoptosis contributes to the side effects of cancer treatment, and genetic or pharmacological inhibition of p53 function can increase normal tissue resistance to genotoxic stress. It has recently been shown that p53 can induce apoptosis through a mechanism that does not depend on transactivation but instead involves translocation of p53 to mitochondria. To determine the impact of this p53 activity on normal tissue radiosensitivity, we isolated a small molecule named pifithrin-mu (PFTmu, 1) that inhibits p53 binding to mitochondria by reducing its affinity to antiapoptotic proteins Bcl-xL and Bcl-2 but has no effect on p53-dependent transactivation. PFTmu has a high specificity for p53 and does not protect cells from apoptosis induced by overexpression of proapoptotic protein Bax or by treatment with dexamethasone (2). PFTmu rescues primary mouse thymocytes from p53-mediated apoptosis caused by radiation and protects mice from doses of radiation that cause lethal hematopoietic syndrome. These results indicate that selective inhibition of the mitochondrial branch of the p53 pathway is sufficient for radioprotection in vivo.     

Protection from radiation nephropathy by WR-2721

The efficacy of WR-2721 pretreatment against radiation injury to the growing kidney was evaluated in the weanling mouse. Immediately following unilateral nephrectomy, animals received intraperitoneal injections of saline or WR-2721 (220 mg/kg). Thirty minutes later both nonprotected (saline-treated) control animals and protected (WR-2721-treated) animals received 1000-rad single-fraction radiation to the remaining kidney. Other animals received WR-2721 immediately following unilateral nephrectomy but no radiation. Animals were sacrificed at 3 and 24 weeks. Nonirradiated animals treated with WR-2721 only showed normal compensatory renal growth, body growth, and renal function at 24 weeks. The nonprotected, irradiated animals exhibited renal growth inhibition without body growth inhibition, and renal functional abnormalities including elevation of serum BUN and reduction of glomerular filtration rate. Pretreatment with WR-2721 prior to 1000 rad prevented the renal growth inhibition and functional abnormalities seen in the nonprotected irradiated animals. Within the observation period there were no differences in renal morphology by light and electron microscopy between protected and nonprotected groups; only mild glomerular and tubular abnormalities compatible with radiation injury were seen. WR-2721 can modulate renal radiation injury; however, the growth and functional protection is not well correlated with specific histologic change. The dose reduction factor for WR-2721 renal growth protection is between 1.16 and 1.2. WR-2721 may have future clinical utility by increasing radiation tolerance of the kidney.     

Protection of drinking water sources against modern pollutants.

One of the main tasks of hygiene necessitating urgent solution is the regulation, within the framework of governmental planning, of sanitary protection against modern pollutants of sources and water works supplying the human collectivities. Pollution by pesticides, surfactants, aromatic polycyclic hydrocarbons, oil waste products, phenolics, radioactive isotopes etc., is requiring particular concern. Cases of penetration of these chemical substances, especially of pesticides, oil residues and other kinds of industrial waste into ground waters have been recently observed with increasing frequency. Pollution of underground waters occurred either through the storage on the surface ground or into soil of waste products containing these substances or through their discharge into the water stream. The presence of these substances in most water supply systems the lowered effectivity of water-works in the removal of these substances, continual increase in the number of industries producing these pollutants, their participation in the origin or increased incidence of some chronic diseases characterizing the development of modern society make necessary scientific substantiation and urgent solution of the problem.     

Interactions of drugs and radiation in haemopoietic tissue assessed by lethality of mice after whole-body irradiation

Drug-radiation interactions in haemopoietic tissue were assessed as the lethality of mice within 7-28 days after whole-body irradiation. The investigated drugs were adriamycin (ADM), bleomycin (BLM), cyclophosphamide (CTX), 5-fluorouracil (5-FU), methotrexate (MTX), mitomycin C (MM-C) and cis-diamminedichloroplatinum II (cis-DDP). The drugs were administered as single doses 15 min before graded doses of whole-body irradiation or at different intervals from 7 days before to 7 days after fixed radiation doses. ADM, CTX, 5-FU, MM-C and cis-DDP enhanced the radiation response when administered 15 min before irradiation. The dose effect factor (DEF) was 9.11 for 5-FU and in the range 1.25-1.59 for the other drugs. MTX administration 15 min before irradiation had no effect (DEF 1.00). However, MTX increased lethality if given 1-3 days after irradiation (DEF 1.21-1.76) and protected against lethality if given 1-3 days before irradiation (DEF 0.83). A similar time dependence was observed for ADM, CTX, 5-FU, MM-C and cis-DDP. Protection against lethality was not observed but in all these cases the lethality was significantly lower at administration 1-3 days before than 1-3 days after irradiation. A proper investigation of the effect of BLM was not possible as the combination of this drug and whole-body irradiation caused a high rate of gastrointestinal deaths.     

Protection of waterborne pathogens by higher organisms in drinking water: a review

Higher organisms are ubiquitous in surface waters, and some species can proliferate in granular filters of water treatment plants and colonize distribution systems. Meanwhile, some waterborne pathogens are known to maintain viability inside amoebae or nematodes. The well-documented case of Legionella replication within amoebae is only one example of a bacterial pathogen that can be amplified inside the vacuoles of protozoa and then benefit from the protection of a resistant structure that favours its transport and persistence through water systems. Yet the role of most zooplankton organisms (rotifers, copepods, cladocerans) in pathogen transmission through drinking water remains poorly understood, since their capacity to digest waterborne pathogens has not been well characterized to date. This review aims at (i) evaluating the scientific observations of diverse associations between superior organisms and pathogenic microorganisms in a drinking water perspective and (ii) identifying the missing data that impede the establishment of cause-and-effect relationships that would permit a better appreciation of the sanitary risk arising from such associations. Additional studies are needed to (i) document the occurrence of invertebrate-associated pathogens in relevant field conditions, such as distribution systems; (ii) assess the fate of microorganisms ingested by higher organisms in terms of viability and (or) infectivity; and (iii) study the impact of internalization by zooplankton on pathogen resistance to water disinfection processes, including advanced treatments such as UV disinfection.     

饮用经臭氧处理的灭菌水与小鼠自发性乳腺肿瘤的发生

目的研究饮用经臭氧处理的灭菌水对小鼠自发性乳腺肿瘤发生的影响。方法给昆明(KM)小鼠、NIH小鼠和BALB/c小鼠饮用经臭氧处理的灭菌水,然后观察其乳腺肿瘤的发生情况,剖检小鼠并从其乳腺、左右肺叶、气管、肺门淋巴结、鼠蹊部淋巴结、心、肝、脾、肾、脑和大小肠等部位取材固定,常规病理制片进行病理组织学检查。结果饮用经臭氧处理的水数月后,KM小鼠、NIH小鼠和BALB/c小鼠,自发性乳腺肿瘤的数量明显增加。发生的乳腺肿瘤均为乳腺腺癌,其中一例为乳头状囊腺癌。乳腺肿瘤均发生在生育3～4胎以上的雌性小鼠。9例中有3例发生肺转移癌。根据乳腺肿瘤发生部位、大体形态特征及病理组织学,结合临床发病情况,即可明确诊断。结论长期饮用经臭氧处理的灭菌水可使小鼠自发性乳腺肿瘤的发生率明显上升。     

Decontamination of spices by gamma radiation

Spices such as coriander, cumin, turmeric, chilli collected from a local market were found to be highly contaminated with bacteria and fungi. A dose of 10 kGy was required to reduce the total bacterial count below detectable levels, while a dose of only 5 kGy was required to eliminate the fungal contamination. Coliforms were totally eliminated at a radiation dose of 5 kGy. During a 6 months storage of irradiated and unirradiated spices, the irradiated spices were found to retain good microbiological quality.     

Sterilization of peat by gamma radiation

Summary The effect of gamma-radiation on the survival of microorganisms has been quantified for the natural population of two types of peat. Data for several microbial types have been separately determined by regular plating and by indirect statistical probability estimates including, a wholly enclosed invertedbottle technique for higher dose levels to exclude any possibility of post-treatment contamination. The most persistent microorganisms at intermediate dosage (2.5–3.5 Mrad) were commonly a micrococcus (which closely resembledMicrococcus radiodurans) arthrobacter-like rods, myxobacteria and amoeboid forms. The persistent organisms all survived because of high resistance to -irradiation, not because of high initial numbers. The most numerous true bacteria (including sporeformers), actinomycetes, filamentous fungi and yeasts were all readily destroyed. Although the safety margin with the commercially recommended dose of 5 Mrad is low for some of the more resistant organisms, no change is justified at this stage since the organisms most likely to survive such a dose do not seem to seriously affect the subsequent growth and survival of rhizobia. Moreover there would be some risk of radiation-induced peat toxicity if higher doses were applied and some post-irradiation contamination will be difficult to avoid in commercial production.     

Genetic effect of chronic gamma radiation exposure in male mice

The frequency of reciprocal translocations (RT) in mouse spermatogonia induced by gamma-rays at doses of 1.5 to 4.5 Gy and dose rates of 2.7 X 10(-6), 5.8 X 10(-6), 9.4 X 10(-5) and 4.5 Gy/min was studied. A linear increase was observed in the RT frequency with increasing the dose, at all dose rates. At 9.4 X 10(-5) Gy/min the RT frequency was, on average, 10 times lower, as compared to that for a single acute dose rate of 4.5 Gy/min. Further reduction of the dose rate did not result in a decrease of the RT yield, and at the lowest dose rate of 2.7 X 10(-6) Gy/min (the dose being 3.0 Gy) the RT frequency was higher than using the same dose at dose rates of 5.8 X 10(-6) and 9.4 X 10(-5) Gy/min. Possible reasons for an increase in the RT frequency at low dose rates are considered. A study of the frequency of abnormal sperm heads (ASH) has shown that at the dose rate of 9.4 X 10(-5) Gy/min it is independent of an accumulated dose and is equal to the value obtained when exposing to an acute dose of 3.0 Gy. At dose rates of 2.7 X 10(-6) and 5.8 X 10(-6) Gy/min ASH frequencies were only slightly increased at all doses, as compared to the control level.     

Effects of slightly acidic electrolysed drinking water on mice

Slightly acidic electrolysed (SAE) water is a sanitizer with strong bactericidal activity due to hypochlorous acid. We assessed the safety of SAE water as drinking water for mice at a 5 ppm total residual chlorine (TRC) concentration to examine the possibility of SAE water as a labour- and energy-saving alternative to sterile water. We provided SAE water or sterile water to mice for 12 weeks, during which time we recorded changes in body weight and weekly water and food intakes. At the end of the experiment, all of the subject animals were sacrificed to assess serum aspartate aminotransferase, alanine aminotransferase and creatinine levels and to examine the main organs histopathologically under a light microscope. In addition, we investigated the bacteria levels of both types of water. We found no difference in functional and morphological health condition indices between the groups. Compared with sterile water, SAE water had a relatively higher ability to suppress bacterial growth. We suggest that SAE water at 5 ppm TRC is a safe and useful alternative to sterile water for use as drinking water in laboratory animal facilities.     

Influence of ginger rhizome (Zingiber officinale Rosc) on survival, glutathione and lipid peroxidation in mice after whole-body exposure to gamma radiation

The radioprotective effect of the hydroalcoholic extract of ginger rhizome, Zingiber officinale (ZOE), was studied. Mice were given 10 mg/kg ZOE intraperitoneally once daily for five consecutive days before exposure to 6-12 Gy of gamma radiation and were monitored daily up to 30 days postirradiation for the development of symptoms of radiation sickness and mortality. Pretreatment of mice with ZOE reduced the severity of radiation sickness and the mortality at all doses. The ZOE treatment protected mice from GI syndrome as well as bone marrow syndrome. The dose reduction factor for ZOE was found to be 1.15. The optimum protective dose of 10 mg/kg ZOE was 1/50 of the LD50 (500 mg/kg). Irradiation of the animals resulted in a dose-dependent elevation in the lipid peroxidation and depletion of GSH on day 31 postirradiation; both effects were lessened by pretreatment with ZOE. ZOE also had a dose-dependent antimicrobial activity against Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli and Candida albicans.