Radiation Protective Effect Research Articles

X線透視時における防護スクリーンの被曝防止効果

X線透視時における防護スクリーンの被曝防止効果

Radiation Induced Cancer from Low Doses of Ionizing Radiation : Risk Analysis Using the Cell Dose Concept

High doses of ionizing radiations are known to bear the risk of cancer to the exposed individual. In order to appreciate potential carcinogenesis from low doses also, the action of ionizing radiation in the human body has to be considered in holistic approach: energy depositions to individual cells trigger effects within a hierarchical structure of interacting levels of biological systems, consisting consecutively of atoms, molecules, cells and organ tissue. The present paper describes the cell dose concept which is an essential factor in assessing the risk due to the ionizing radiation to the cells and tissues. Low dose of ionizing radiation induces adaptive response in individual cells which could be linked to the action of molecular radicals. Enzyme activities in bone marrow cells and bilayer lipid membranes and radicals are directly related to radiation effects. Temporary improvements of the detoxification of molecular radicals also improve the cellular defence. The risk analysis calls for more attention as it is important for radiation protection and other beneficial effects due to low doses of irradiation.

放射線障害防護薬剤に関する研究(第30報)川〓中の放射線障害防護物質

Radiation protective effects of the methanol extract and its fractions of Cnidii Rhizoma on lethality and skin injury induced by X-irradiation were studied. As a result of these studies, it was observed that significant protective effects exist in both ether and water soluble portions prepared from the above methanol extract, and two of the active principles in the ether and water soluble ones were identified as ferulic acid and adenosine, respectively.

The Ability of Ethanolic Extract of Propolis (EEP) to Protect Mice against Gamma Irradiation

Ethanolic extract of propolis (EEP) was tested as a protective agent against gamma irradiation in mice. The mice were exposed to 6 Gy gamma irradiation from a 60Co source, and were treated intraperitoneally with EEP, administered before and after their irradiation. While the non-treated mice expired within 12 weeks, the mice that received a series of EEP treatments survived the irradiation, and their leucocyte count as well as their spleens' plaque-forming activity returned to normal. It is suggested that an antioxidant and a free radical scavenger in the EEP are responsible for the radiation protective effect of the extract of this natural product.

Effects of ginseng protein on relative survival and chromosome aberration of UV irradiated cells

A ginseng protein fraction which has been reported to have radiation protective effect was purified from Korean ginseng and its effects on relative survival and chromosome aberration were studied in UV irradiated CHO-K1 cells. When the protein fraction (100 μg/ml) was added to the cells before UV irradiation at 4 J/m2, the survival rates were increased to 53.8% from 40.6% in control. Addition of the protein (100 μg/ml) after UV irradiation at 4 and 8 J/m2 raised the rates to 85.4 and 24.0% from 79.2 and 11.5% in control, respectively. When the ginseng protein (800 μg/ml) was added to the cells exposed to UV light at 10, 20, 30 J/m2, the frequencies of chromosome aberration (CA) were reduced significantly to almost same level regardless of the UV dose increment and there was no significant difference between pre- and post-treatment. When the concentration of ginseng protein was increased from 200 to 800 μg/ml, at UV dose of 10, 20, 30 J/m2 each, the CA frequencies were decreased consistently as the dose of ginseng protein increased, at all UV doses tested. Similar effects were observed in both cases of pre- and post-treatment. The data suggest that the protein may reduce cell damage caused by UV light, especially damage to DNA molecule, or play a role in repair processes of damaged DNA, to increase cell survival and reduce chromosome aberrations.

Study of the radiation protection effect of selenium-methionine by determining the paramagnetic properties of liver tissues of mice

The paramagnetic properties of the liver tissues were observed after the change which took place during 3, 18 and 24 hours following the administration of s-methionine or alternatively of se-methionine and subsequent irradiation. The signals recorded were those characteristic of P-450 citochrome, free radicals of the semichinon type, Mo-protein and Fe-s-protein. Spectra of these paramagnetic centres generally show the changes in activity of the ferments characteristic for the tissue, which is closely related to the increased or decreased functional activity of the liver tissues [1,2].

Effect of lactate on the recovery of CHO-KI cells from gamma radiation damage.

The effect of pre-exposure of CHO-KI cells to lactate on their capacity to recover from or repair radiation damage was examined. Prolonged pre-exposure to lactate and a number of inhibitors of glycolysis has previously been shown to reduce the cell survival after irradiation. Following a split dose of irradiation, cells pre-treated with lactate for 18 hours had a higher relative recovery factor than controls even though survival following a single dose was reduced. Where lactate was added just before irradiation it had a radiation protective effect on the single dose survival curve and no effect on recovery. To investigate a possible involvement of NADH generation via lactate dehydrogenase in the mechanism, oxamate, a non-metabolisable analogue of lactate, was investigated. It reduced the survival of irradiated CHO-KI cells following prolonged and short pre-exposure and did not significantly affect the recovery factor. It is suggested that since lactate and oxamate both inhibit glucose breakdown, their radiobiologic effects may be due to depletion of cellular energy substrates necessary for repair. In contrast, the increased recovery and short term radiation protective effect seen with lactate only may involve LDH activity.

Pulse radiolysis studies on radiation resistance of epoxy resin

The mechanisms of radiation damage in epoxy resin, especially the primary processes, have been studied by a time-resolved spectroscopic technique (pulse radiolysis). The difference between the radiation resistance of aromatic and aliphatic amine curing epoxy resin is explained by internal radiation protection effects due to energy and charge transfer on the basis of the time-resolved spectroscopic data of reactive intermediate (excited states and ions) in an irradiated epoxy resin.

Energy transfer in radiation chemistry: Mechanism of the radiation protection effect

In the study of the radiation stability and the protective effect of some linear conjugated systems, many experiments have been performed about the dependence of the G-value on molecular size. In this paper, we analyze this dependence by using the Hückel molecular orbital theory, especially the graphical method, and connecting with the consideration of the fundamental radiation- chemical processes of aromatics. Based on above analysis a qualitative rule relating the radiation stability and the radiation protective effect to the linear molecular size has been suggested.

Effect of glutaurine and its derivatives and their combinations with radiation protective substances upon irradiated mice.

The radiation protective effects of glutaurine (gamma-L-glutamyl-taurine, Litoralon), and of some of its derivatives, as well as of their combinations with substances of the amino-alkyl-thiol group, have been investigated in mice. The results suggest that glutaurine possesses a radiation protective effect in animals irradiated with LD50/30 of roentgen rays and 60Co gamma rays. The compound has a favourable effect also when administered after irradiation. Its protective effect is especially marked in case of prolonged irradiation. Among the combinations best results were obtained by its simultaneous administration with subminimal doses of AET or cystamine. Some of its derivatives also exhibited considerable protection against irradiation with roentgen rays.

E.S.R. studies of mechanisms of radiation protection effect by cysteine and cystine

By means of E.S.R. we have first confirmed the repair mechanism of radiation induced spin transfer from dTMP to cycteine in binary system dTMP-cysteine. Furthermore, we have detected a new marked radiation protection effect exerted by cysteine or cystine on thymine irradiated and observed at low temperature and another sort of fast protection mechanism, including electron transfer and excitation transfer, has been proposed based on recent advances of primary radiation process of pyrimidine bases and analysed by molecular orbital theory. This fast radiation protection mechanism provides the possibility to utilize electrophilic sulfhydryl protectors for realizing excellent protection effect.

ESR studies of radiation protection effect by cysteine and cysteamine

By means of ESR we have confirmed a large transfer of radiation induced spins from thymine or cytosine to cysteamine in these binary systems. Furthermore, by substituting paramethylbenzenesulfonate of cysteine for its hydrochloride, we also succedded in observing marked protection effect of cysteine on thymine or dTMP in the above binary systems. The mechanism of this effect is briefly discussed.

Lack of radiation protective effect of orgotein in normal and malignant mammalian cells.

The potential radiation protective effect of orgotein, a metalloprotein with superoxide dismutase activity, was investigated in L1A2 tumour cells in vitro, jejunal crypt cells and C3H mouse mammary carcinoma in vivo. No effect of orgotein, given either 2 hours before irradiation or 30 min after, was observed compared to the effect of irradiation alone. Thus, it was concluded that orgotein did not influence the primary radiation response in air in mammalian cells.

Synthetic Glycolipid Adjuvants

In the course of the organic synthesis of model compounds similar in some features to the lipid moiety of endotoxic lipopolysaccharide (LPS), Nacylated-D-glucosamine derivatives were prepared. One of these, N-palmitoyl-D-glucosamine, has been previously found to be mitogenic for athymic nude mouse B cells. This and other N-acylated homologs were tested for adjuvant activity in the immune response to human gamma-globulin (HGG) and sheep red blood cells (SRBC) in mice. Comparable or superior enhancement of the immune response was obtained for these glycolipids when compared to LPS in assays measuring anti-SRBC or HGG hemagglutinin titers. In the determination of hemolytic plaque formation, considerable adjuvant effect was shown by the lauroyl derivative, and less but still significant enhancement was achieved by the N-palmitoyl-D-glucosamine. In the rosette formation assay, in addition to the above two glycolipids, N-oleyl-D-glucosamine showed good adjuvant effect. In the latter two assays, the LPS was a superior adjuvant as compared to the synthetic glycolipids. The radiation protective effect of some of the better synthetic adjuvants was also investigated in mice. It was found that although LPS was more effective in this assay, the N-myristoyl-D-glucosamine and N-decanoyl-D-glucosamine compounds gave a definite protection, since up to 40% of the lethally irradiated (700 R) mice survived.

Radiation Chemical Studies of Protein Reactions: Effect of Amino Acids and Vitamins on the Breaking of Secondary Bonding in Protein

Abstract The radiation protective effect of the breaking of secondary bonding in protein was examined with such amino acids as disodium inosine-5′ -monophosphate and disodium guanosine-5′ -monophosphate and vitamins such as thiamine and λ-ascorbic acid. The behavior of the viscosity change closely resembles that found with the sodium 1-glutamate as shown by a similar dependence on concentration.

Radiation Chemical Studies of Protein Reactions: Effect of Alkaline-Earth Metals on the Breaking of Secondary Bonding in Protein

Abstract The radiation protective effect of the breaking of secondary bonding in protein was examined with alkaline-earth metals such as magnesium chloride, calcium chloride, strontium nitrate, and barium chloride, and alkaline metals and heavy metals such as lithium chloride, sodium chloride, potasium nitrate, ferrous chloride, ferric sulfate, nickel sulfate, aluminum nitrate, and zinc sulfate. An empirical equation for the viscosity change was obtained.

Radiation Chemical Studies of Protein Reactions: Effect of Chelating Agents on the Breaking of Secondary Bonding in Protein

Abstract The radiation protective effect of the breaking of secondary bonding in proteins was examined with 1,2 diamine and 1,2 dihydroxy derivatives such as ethylenediamine, ethylenediaminetetraacetic acid, and propylene glycol, and monosubstituted amines and alcohols such as ethylamine and n-propyl alcohol. An empirical equation for the viscosity change was obtained.

The radiation induced reactions of aqueous polyethylene oxide systems. III. Radiation chemistry of polyethylene oxide in tert‐butyl alcohol/water systems

AbstractA satisfactory explanation for the complex radiation induced changes in polyethylene oxide in deaerated aqueous alcohol systems of relatively high alcohol content can be put forward only on the basis of both the radiation protection effect and water perturbation effect of the alcohol. Strong evidence is obtained which supports an earlier suggestion that preferential adsorption of alcohol by polyethylene oxide in aqueous solution occurs at low alcohol concentrations and decreases with increasing alcohol concentration.

Quantitative Radiation Effects in Hemoproteins and their Constituents

In order to verify the "radiation protection" effect of prosthetic groups in irradiated conjugated proteins and the influence of their electronic structure on intramolecular excitation transfer, two series of substances were examined. The first was composed of ferrihemoglobin and its constituents and the second was composed of similar hemoproteins with heme groups with major differences in electronic structure. The results point to a strong radiation protection effect of the heme groups and a dependence of radical yield of hemoproteins on the electronic structure of the heme. A possible interpretation of this latter effect is discussed.

Über den Einfluß verschiedener Glycerinkonzentrationen auf die Ausbeute in einem Eisen(II)-sulfat-Dosimeter (Fricke-Dosimeter)

The oxidation of ferrous to ferric iron is used as a measure of the effect of ionizing radiation in Fricke dosimeter solution in the presence of glycerine at various concentrations. At low glycerine concentrations the sensitivity of the system to X-rays was found to be increased by the presence of the alcohol while at higher concentrations a radiation-protection effect was observed. The increased sensitivity rose to a maximum at glycerine concentrations of 0.01 to 0.1 Mol, the size of the maximum depending on the duration of the radiation. The peak represents a sensitivity of about twice the normal ion conversion. The falling off at low concentrations is explained on the basis of a model where the presence of alcohol leads directly to increased ferric ion yield, that at high concentrations as being due to increased viscosity of the system. Other alcohols showed similar results.