[en] Morphine and endorphin administered intracerebroventricularly (i.c.v.) produce analgesia by activating different descending pain inhibitory systems. Gamma irradiation attenuates the acute analgesic action of i.c.v. injected morphine in mice. This study was done to investigate the effect of-irradiation on the analgesia produced by i.c.v. injected morphine and endorphin in male ICR mice. In one group, mice were exposed to whole-body irradiation at a dose of 5 Gy from a ⁶⁰Co source and the analgesic effects were tested 5, 30, 60, 90 and 180 min after irradiation using the acetic acid-induced writhing test. The analgesic effect was produced time-dependently and reached its maximum at 90 min after irradiation. Thus, time was fixed in the following studies. In another group, mice were irradiated with 5 Gy and tested 90 minutes later for analgesia produced by i.c.v. administration of morphine or endorphin. Irradiation significantly potentiated the analgesia produced by endorphin. However, the antinociception produced by morphine was not affected by irradiation. These results support the hypothesis that morphine and endorphin administered supraspinally produce antinocieception by different neuronal mechanisms

[en] High-k gate stack fabrication via atomic layer deposition (ALD) of ultra thin HfO2 and HfxSi1-xO2 films is demonstrated utilizing metal-amide precursors and ozone as an oxidant. High resolution transmission electron microscopy (TEM) shows that films near 2.0 nm are reproducible. X-ray reflectivity (XRR) and Rutherford backscattering (RBS) indicate that this ALD chemistry proceeds similarly on multiple surface preparations including HF last without growth incubation. High field mobility of more than 85% of the universal SiO2 mobility has been achieved at EOT ∼1nm with a reduction of more than two orders of magnitude in leakage current density as compared with a SiO2/poly Si gate. Various ALD metal nitrides such as TiN, HfN, HfSiN have been deposited on HfO2 and HfSiOx dielectrics which enabled a study of the interfacial reaction between high-k dielectrics and metal electrode materials. The thermal stability of PVD Ru deposited on ALD HfO2 has also been observed

[en] The kinetics of the liquid holding recovery was experimentally studied for diploid yeasts of wild type and some radiosensitive mutants after irradiation with gamma rays and alpha particles. A mathematical model describing the process of postirradiation recovery as a change in the effective dose was applied to experimental data obtained. The model allowed to estimate quantitatively the probability of recovery per time unit and the irreversible component, i.e. the fraction of cells incapable of recovery. It was shown that the irreversible component was enhanced for densely ionizing radiation in comparison with low-LET radiation while the probability of recovery was identical both for low- and high-LET radiations for all strains investigated. It was concluded on this basis that the recovery process itself is not damaged after densely ionizing radiation and the enhanced RBE of high-LET radiation may be caused by the increased yield of irreversible damage. Both parent strain and all radiosensitive mutants were characterised by the same probability to recover from radiation damage. It follows that the mechanism of the enhanced radiosensitivity of mutant cells is not related with the damage of repair systems themselves

[en] The oxygen effect in radiation biology is well known. Since oxygen enhances radiation-induced biological damage, antioxidants should be radioprotectors. Ascorbic acid (vitamin C) or caffeine is an essential component in the diet of humans and a small range of other mammals. Radioprotective effects of vitamin C have been demonstrated in certain cells and animals, which would result from scavenging free radicals. Caffeine is the main psychoactive ingredient of coffee, tea, even coke with a high frequency of concurrent use in humans. Caffeine has been recently reported as a scavenger of hydroxyl radical in millimolar levels and a potently radioprotector in a chronically exposed rodent. This study investigates functional radioprotection of caffeine and ascorbic acid against gamma irradiation in male mice. Eight-week-old male C57BL/6N mice were irradiated with 6.5 Gy. A caffeine treated group was administered with 80 mg/kg body weight by i.p injection, a single exposure 1 hour before irradiation. Ascorbic acid was administered 330 mg/liter in drinking water through all the experimental period. The remaining mice were kept as sham controls. After collecting a serum from the experimental mice 6 hr after irradiation, qualitative analysis of testosterone was performed by means of radioimmunoassay (RIA). For histological investigation, testes were removed 1 week after irradiation and fixed in NBF. Fixed testes were processed for paraffin sections and stained by H-E. The circulating testosterone significantly decreased in all irradiated groups. The harmful effect of radiation on the body and organ weight and the appearance of semiferous tubules were significantly improved in the caffeine - or ascorbic acid-treated group. In conclusion, caffeine and ascorbic acid protected spermatogenesis from impairment against gamma radiation, acting as a radioprotector

[en] Experimental data obtained for the simultaneous action of hyperthermia with different physical or chemical agents on various cellular systems give evidence that the lesser the intensity of physical factor or the concentration of chemical agents, the lower the temperature has to be used to provide the highest or a definite level of synergistic interaction. On this basis, it is inferred that the synergism may take place at small intensities of harmful environmental factors existing in the biosphere. Hence, the assessment of health or environmental risks should take into account the synergistic interaction between harmful agents

[en] It is widely accepted that the RBE of ionizing radiation with a high linear energy transfer (LET) is dependent both on the increased probability of primary damage production (physical events) and the reduced ability of a cell for post-irradiation recovery (biological events). A relatively unexpected role of the specific repair pathways in the RBE of high-LET radiation was demonstrated for bacterial, yeast and mammalian cells. It seems to exist a common agreement that high-LET radiations produce more portion of damage that are considered to be irreversible compared with low-LET radiation such as photons. Cellular recovery and repair of radiation-induced DNA double-strand breaks (DSB) could be also dependent upon radiation quality. Studies concerning the rate of the recovery and repair from radiation damage produced with low- and high-LET radiations in cells of various origins on the survival and macromolecular level have also revealed that in general at a high ionization density, these processes may be reduced or even absent. When irradiated yeast cells are held in a liquid non-nutrient media at 30 .deg. C before planting on to a growth medium, their survival increases. This phenomena is known as liquid holding recovery (LHR). A quantitative approach describing the LHR kinetics of the yeast cells was described, which enables the estimation of the probability of the recovery per unit time and the fraction of the irreversible damage. The main goals of this study were (i) to answer the question whether or not high-LET radiation affects the recovery process itself or if it only produces a higher level of severe irreversible damage that cannot be repaired at all; (ii) to elucidate the role of irreversible damage and the probability of recovery in some rad mutants of the yeast Saccharomyces cerevisiae. In this study, the liquid-holing recovery will serve as an indicator of the cellular repair activity

[en] The effect of a water-soluble extract from natural materials on radiation-induced mutations was studied by means of TSH assay in Tradescantia 4430 stamen hair cells. Inflorescence cuttings, with or without pretreatments of natural extracts for 3 hours, were exposed to 1 Gy of gamma ray. Comparisons were made on the basis of pooled data during the peak interval between the mean pink mutation frequencies of the experimental groups. Pretreatments of FB or FB-I resulted in about two-fold increases of the pink mutation frequencies, compared to those of the control group. Synergism between certain fractions and radiation was a possible cause of the increased DNA damage. FB and FB-I had a radiosensitizing effects on the pink mutation in Tradescantia 4430 stamen hair cells (p<0.001). On the other hand, the extract PP in a proper concentration significantly reduced the pink mutation frequencies (p<0.05). The result means that PP has a protective effect on the radiation-induced cell damage. (author)

[en] This study deals with the effect of some natural extracts on the pink mutations induced by radiation in Tradescantia 4430 stamen hair cells. Inflorescence cuttings, with or without pretreatments of natural extracts for 3 hours, were exposed to 1 Gy of gamma ray. Comparisons were made on the basis of pooled data during the peak interval between the mean pink mutation frequencies of the two experimental groups. Pretreatments of FB or FB-I resulted in two-fold increases of the pink mutation frequencies, compared to those of control group. Synergism between certain fractions and radiation was a possible cause of increased DNA damage. On the other hand, the extract PG in proper concentrations significantly reduced the pink mutation frequencies (p<0.05). The result meant that PG had a protective effect on radiation-induced cell damage. Tradescantia proved to be an excellent biological model system for assessing the radiomodification effects of natural materials

[en] This study deals with the combined effect of radiation with mercuric chloride on Tradescantia somatic cell pink mutation. Tradescantia BNL 4430 was used as an experimental material. The somatic cell of Tradescantia are very sensitive to chemical toxicants or ionizing radiation, and thus can be used as a biological end-point assessing their effect

[en] Radiation technology is currently used in a number of industrial processes such as sterilization, cross linking of polymer, food irradiation, rubber vulcanization in the tire manufacturing, contaminated medical waste, etc. Gamma ray and electron beam are the key examples of well-established economical applications of radiation processes. The purpose of this paper is to review the recent technological trends and activities for radiation processes in order for the industrial end users to better understand, and obtain useful information about the technology. It is clear that the radiation processing technology has potential for a variety of the industrial applications