The response of previously irradiated skin to combinations of X radiation and ultrasound-induced hyperthermia

Areas of skin approximately 1.5 cm in diameter on the legs of mice were made hyperthermic (30 min at 42.7 degrees C) by exposure to an ultrasound beam (780 kHz), a single dose of X irradiation (2000 rad), or a combination of these treatments. After 35 days, when the acute reaction had reached a steady state, the same tissue was given a second treatment by either hyperthermia, irradiation, or a combination of hyperthermia and irradiation. When the first treatment was irradiation and the second treatment was either irradiation or a combination of hyperthermia and irradiation, the acute skin reactions were similar to those of skin not previously irradiated, indicating a large proportion of recovery from the first irradiation. When irradiation was the first treatment, a comparison of second treatments by hyperthermia plus irradiation with irradiation alone showed a thermal enhancement of 1.45. When the first treatment was hyperthermia plus irradiation, a comparison of second treatments by hyperthermia plus irradiation with irradiation also showed an enhancement factor of 1.45 for the combined treatment.     

UV-C照射对苦荞芽生长及品质的影响

以苦荞为材料,研究了不同时间UV.C照射对苦荞芽生长及品质的影响,结果表明：UV-C照射对苦荞芽株高有一定的抑制作用;UV-C照射可以增加苦荞芽的茎粗,平均增粗4.25%;UV-C照射对苦荞芽根长的抑制作用不明显;短时间UV-C照射抑制苦荞芽鲜重的效应不明显;短时间UV-C照射可以提高苦荞芽叶绿素的含量,平均比对照提高24.58%;UV-C照射可以提高苦荞芽总黄酮和Vc的含量,平均分别提高11.42%和23.38%;短时间UV-C照射可以促进苦养芽氨基酸含量的提高,平均挺高22.52%,长时间照射降低苦养芽氨基酸的含量.     

Effect of irradiation on cytokine secretion and nitric oxide production by inflammatory macrophages

This study explored the effects of low-dose and high-dose irradiation on inflammatory macrophage cells, specifically inflammatory cytokine secretion and nitric oxide (NO) production after irradiation. To elucidate the effect of irradiation on active and inactive macrophages, we exposed LPS-treated or untreated murine monocyte/macrophage RAW 264.7 cell lines to low-dose to high-dose radiation (0.01–10 Gy). We analyzed the effects of irradiation on RAW 264.7 cell proliferation by MTT assays and analyzed cytokine secretion and NO production related to inflammation by ELISA assays. Low-to-high doses of radiation did not significantly affect the proliferation of LPS-treated or untreated RAW 264.7 cells. Pro-inflammatory cytokine IL-1ß was generally increased in RAW 264.7 cells at 3 days after radiation. Especially, IL-1ß was significantly increased in only high dose-irradiation (2 and 10 Gy irradiation) groups in LPS-untreated RAW 264.7 cells but increased in both low and high dose-irradiation groups (0.01–10 Gy) in LPS-treated RAW 264.7 cells at 3 days after irradiation. Whereas, the expression of IL-1ß was prolonged in high-dose irradiation group at 5 days after irradiation. The production of anti-inflammatory cytokine IL-10 did not change significantly at 3 days after radiation but was significantly reduced at 5 days after 10 Gy radiation. The effect of irradiation on the secretion of IL-1ß and IL-10 was not significantly different between RAW 264.7 cells treated or not treated with LPS. The effect of irradiation on NO secretion by RAW 264.7 cells showed a specific pattern. NO was produced after low-dose irradiation but reduced in a high-dose irradiation group at 3 days after irradiation. However, NO production was not changed after low-dose irradiation and reduced at 5 days after high-dose irradiation. These results showed that irradiation affected the inflammatory system and regulated NO production in both activated and inactivated macrophages through different regulation mechanisms, depending on irradiation dose.     

Reduced side effects by proton microchannel radiotherapy: study in a human skin model

The application of a microchannel proton irradiation was compared to homogeneous irradiation in a three-dimensional human skin model. The goal is to minimize the risk of normal tissue damage by microchannel irradiation, while preserving local tumor control through a homogeneous irradiation of the tumor that is achieved because of beam widening with increasing track length. 20 MeV protons were administered to the skin models in 10- or 50-μm-wide irradiation channels on a quadratic raster with distances of 500 μm between each channel (center to center) applying an average dose of 2 Gy. For comparison, other samples were irradiated homogeneously at the same average dose. Normal tissue viability was significantly enhanced after microchannel proton irradiation compared to homogeneous irradiation. Levels of inflammatory parameters, such as Interleukin-6, TGF-Beta, and Pro-MMP1, were significantly lower in the supernatant of the human skin tissue after microchannel irradiation than after homogeneous irradiation. The genetic damage as determined by the measurement of micronuclei in keratinocytes also differed significantly. This difference was quantified via dose modification factors (DMF) describing the effect of each irradiation mode relative to homogeneous X-ray irradiation, so that the DMF of 1.21 ± 0.20 after homogeneous proton irradiation was reduced to 0.23 ± 0.11 and 0.40 ± 0.12 after microchannel irradiation using 10- and 50-μm-wide channels, respectively. Our data indicate that proton microchannel irradiation maintains cell viability while significantly reducing inflammatory responses and genetic damage compared to homogeneous irradiation, and thus might improve protection of normal tissue after irradiation.     

Teniposide (VM-26) treatment enhances the radiation-induced micronuclei in the bone marrow of mouse

The effect of Teniposide (VM-26) pretreatment was studied on the micronuclei induction in the bone marrow of mice exposed to 0, 0.5, 1, 2 and 3 Gy of gamma radiation at 12, 24 and 36 h post-irradiation. Administration of 0.05 mg/kg body weight of VM-26 to mice before irradiation resulted in the significant enhancement of micronucleated polychromatic erythrocytes (MPCE) at 12, 24 and 36 h post-irradiation. Highest elevation in the frequency of MPCE was observed in VM-26+irradiation group after exposure to 0.5 Gy when compared to concurrent DDW+irradiation group. This increase was two fold higher in VM-26+irradiation group at 12 and 24 h, while it was 3 fold higher at 36 h post-irradiation compared to DDW+irradiation group. The peak frequency of MPCE was observed at 24 h post-irradiation in both groups, which declined thereafter. The frequency of micronucleated normochromatic erythrocytes (MNCE) increased in a dose dependent manner in both DDW+irradiation and VM-26+irradiation groups. However, the frequency of MNCE was significantly higher in the latter when compared to the former group. The frequency of MNCE exhibited a continuous elevation up to 36 h post-irradiation in both DDW+irradiation and VM-26+irradiation groups. Treatment of mice with teniposide before irradiation resulted in a significant decline in the PCE/NCE ratio compared to DDW+irradiation group. The PCE/NCE ratio continued to decline up to 36 h post-irradiation in both the groups. The dose response for MPCE and PCE/NCE ratio was linear quadratic, while it was linear for MNCE.     

Physiological responses of mangoes cv. Kensington Pride to gamma irradiation treatment as affected by fruit maturity and ripeness

An investigation was undertaken to examine responses of mangoes cv. Kensington Pride to irradiation treatment.
Gamma irradiation of preclimacteric fruit increased fruit respiration immediately after treatment, delayed the time to attain the climacteric respiratory peak and reduced the magnitude of this peak rate. Fruit softening was unaffected whereas skin colour development was strongly inhibited by irradiation treatment. Inhibition of skin degreening was half-maximal at a dose of 200 Gy. Exposure to ethylene failed to reverse this inhibition. Less mature fruit were more strongly affected by irradiation treatment. Fruit which were partially ripe and in their climacteric rise at time of treatment were largely unaffected by irradiation. These results are discussed in terms of the utility of irradiation technology for commercial disinfestation.     

γ-Irradiation of PEGd,lPLA and PEG-PLGA Multiblock Copolymers: I. Effect of Irradiation Doses

To evaluate the effects of different gamma irradiation doses on PEGd,lPLA and PEG-PLGA multiblock copolymers. The behaviour of the multiblock copolymers to irradiation was compared to that of PLA, PLGA polymers. PEGd,lPLA, PEG-PLGA, PLA and PLGA polymers were irradiated by using a ⁶⁰Co irradiation source at 5, 15, 25 and 50 kGy total dose. Characterization was performed on all samples before and after irradiation, by nuclear magnetic resonance (NMR), infrared absorption spectrophotometry (FTIR) and gel permeation chromatography (GPC). The effect of gamma irradiation on polymer stability was also evaluated. Results of NMR and FTIR suggest an increase in -OH and -COOH groups, attributed to scission reactions induced by irradiation treatment. Data of GPC analysis showed that the weight average molecular weight (Mw) of polymer samples decreased with increasing irradiation dose. The extent of Mw degradation expressed as percentage of Mw reduction was more prominent for polymers with high molecular weight as PEGd,lPLA and PLA. The dominant effect of gamma-irradiation on both polymer samples was chain scission. The multiblock copolymer PEGd,lPLA presented higher sensitivity to irradiation treatment with respect to PLA, likely due to the presence of PEG in the matrix. The effect of gamma irradiation continues over a much longer period of time after gamma irradiation has been performed. It is suggested that the material reacts with oxygen to form peroxyl free radicals, which may further undergo degradation reactions during storage after irradiation.     

Chronic irradiation with low doses can be characterized by significant biological efficacy

Chromosomal aberrations (ChA) level was analyzed in the onion root meristem after the chronic irradiation with different dose capacities. It was shown that after the chronic irradiation with doses of 0.87 cGy, 2.61 cGy and 4.35 cGy the level of chromosomal aberrations depended on the dose capacity. Its value may also correspond to those which have been induced with accute irradiation. Biological efficacy of chronic irradiation may be from 20 to 1000 time folder in order to compare it with accute irradiation and this value depends on the irradiation regime.     

长期低剂量γ线照射和照射加电击对老年前期大鼠性激素、肝功能和脂质过氧化物的影响

本文观察了长期低剂量γ射线照射和照射加电击对老年前期(18～21月龄)大鼠血浆性激素水平、肝微粒体混合功能氧化酶(MFO)活力以及组织脂质过氧化物的影响。长期照射加电击使雄性大鼠血浆睾酮水平明显降低(p<0.05),照射与照射加电击均使雄鼠肝微粒体MFO活力明显下降(p<0.05)。长期低剂量γ射线照射和照射加电击组的睾丸自由基浓度较对照组明显升高(p<0.05),长期照射使雄性大鼠肝匀浆与微粒体,睾丸匀浆与线粒体的脂质过氧化物较对照组明显增高,但照射加电击组的脂质过氧化物较照射组(以及对照组)明显下降。实验结果说明照射与照射加电击对老年前期大鼠的作用有所不同,这些环境因素具有加速老化的作用。     

Assessment of supra-additive effects of cytotoxic drugs and low dose rate irradiation in an in vitro model for hepatocellular carcinoma

The use of 5-fluorouracil, topotecan, or gemcitabine was tested for enhancement of the effects of low dose rate (LDR) irradiation in an in vitro model for hepatocellular carcinoma. For comparison, all drugs were tested in combination with high dose rate (HDR) gamma-irradiation as well. Multicellular spheroids of HepG2 cells were exposed to HDR or LDR irradiation by means of external beam cobalt-60 or rhenium-188 (188Re), respectively, dissolved in the culture medium. Secondly, exposure to irradiation was combined with the cytotoxic drug. Toxicity was evaluated by means of a quantitative spheroid outgrowth assay and histology. For 5-fluorouracil, supra-additive effects were observed in combination with HDR irradiation. With 188Re, the supra-additive toxicity was only transient. For topotecan and 188Re, no supra-additive effects were seen, whereas the addition of HDR irradiation at the end of the topotecan exposure yielded lasting supra-additive effects. Incubation with gemcitabine followed by exposure to HDR irradiation, induced a synergistic toxicity on the outgrowth. No supra-additive effects were observed when HDR irradiation was added at the start of the incubation with gemcitabine or combined with LDR irradiation. For all drugs tested, supra-additive effects were observed with HDR irradiation if the timing of the irradiation was appropriate. For 188Re, no lasting supra-additive effects were observed.     

60Co irradiation of Shiga toxin (Stx)-producing Escherichia coli induces Stx phage

Shiga toxin (Stx)-producing Escherichia coli (STEC), an important cause of hemolytic uremic syndrome, was completely killed by (60)Co irradiation at 1 x l0(3) gray (1 kGy) or higher. However, a low dose of irradiation (0.1-0.3 kGy) markedly induced Stx phage from STEC. Stx production was observed in parallel to the phage induction. Inactivation of Stx phage required a higher irradiation dose than that for bacterial killing. Regarding Stx, cytotoxicity was susceptible to irradiation, but cytokine induction activity was more resistant than Stx phage. The findings suggest that (1). although (60)Co irradiation is an effective means to kill the bacteria, it does induce Stx phage at a lower irradiation dose, with a risk of Stx phage transfer and emergence of new Stx-producing strains, and (2). irradiation differentially inactivates some activities of Stx.     

Raman spectroscopic analysis of the effect of ultraviolet irradiation on calf thymus DNA

Raman spectroscopy was used for the first time to detect the effect of independent UVA (ultraviolet-A: 320-400nm) and UVB (ultraviolet-B: 280-320 nm) irradiation on the calf thymus DNA in aqueous solution. After both UVA and UVB irradiation for 1h or 3h, the damage to the conformation of DNA was moderate, but the reduction of the B-form DNA component was obvious. Both UVA and UVB caused significant damage to the deoxyribose moiety and bases, among which the pyrimidine base pairs were more seriously affected. There appeared to be preferential damaging sites on DNA molecules caused by UVA and UVB irradiation. UVA irradiation caused more damage to the deoxyribose than UVB irradiation, while UVB irradiation caused more significant damage to the pyrimidine moiety than UVA irradiation. After UVB irradiation for 3h, unstacking of the AT base pairs and the cytosine ring took place, severe damage to the thymine moiety occurred, and some base pairs were modified. Moreover, with either UVA or UVB irradiation for 3h,the photoreactivation of DNA occurred. The damage to the DNA caused by UVB was immediate, while the damage caused by UVA was proportional to the irradiation duration. The experimental results partly indicate the formation of some cyclobutane pyrimidine dimers and (6-4) photoproducts.     

Mutation induction by very low dose rate gamma rays in cultured mouse leukemia cells L5178Y

Induction of cell killing and mutation to 6-thioguanine resistance was studied in growing mouse leukemia cells in culture following gamma rays at dose rates of 30 Gy/h, 20 cGy/h, and 6.3 mGy/h, i.e., acute, low dose rate, and very low dose rate irradiation. A marked increase was observed in the cell survival with decreasing dose rate; no reduction in the surviving fraction was detected after irradiation at 6.3 mGy/h until a total dose of 4 Gy. Similarly, the induced mutation frequency decreased after low dose rate irradiation compared to acute irradiation. However, the frequency after irradiation at 6.3 mGy/h was unexpectedly high and remained at a level which was intermediate between acute and low dose rate irradiation. No appreciable changes were observed in the responses to acute gamma rays (in terms of cell killing and mutation induction) in the cells which had experienced very low dose rate irradiation.     

Lipid metabolism in the cells of the intestinal mucosa in the early and late periods after gamma irradiation in rats]

Two hours following 20 Gy irradiation of rats cholesterol synthesis in crypt cells was activated, and 24 h after 4 Gy irradiation it was inhibited in crypt cells and activated in villus cells. Remote effects of fractionated irradiation (6 Gy) on lipid metabolism in the intestinal cells were observed during a period of six months following irradiation. Cholesterol and phospholipid synthesis activation in crypt cells was observed during the first months following irradiation, and in villus cells after 3 and 6 months, whereas the phospholipid synthesis in these cells was inhibited throughout the entire period of observation.     

Inactivation of Lactobacillus Bacteriophage PL-1 by Microwave Irradiation

The effect of microwave irradiation on the survival of bacteriophage PL-1, which is specific for Lactobacillus casei, was studied using a commercial 2,450 MHz microwave oven. The phages were inactivated by microwave irradiation according to almost first-order reaction kinetics. The rate of phage inactivation was not affected by the difference in the continuous or intermittent irradiation, nor by the concentrations of phages used, but was affected by the volume of phage suspensions, which prevented the loss of generated heat. Microwave irradiation of phage suspensions produced a number of ghost phages with empty heads, but fragmentation of the tail was hardly noticed. The breakage of phage genome DNA was primarily caused by the heat generated by microwave irradiation, whereas the phage DNA was not affected by the same temperature achieved by heat from outside. Thus we concluded that the phage-inactivating effect of microwave irradiation was mainly attributed to a thermal microwave effect, which was much stronger than a simple thermal exposure.     

Rhizoid Differentiation in Spirogyra: III. Intracellular Localization of Phytochrome

Localization of phytochrome which mediates rhizoid differentiation in Spirogyra was investigated. The red-absorbing form of phytochrome (Pr) seems to be distributed all over the cell periphery which remained in the centripetal end part after the centrifugation, as rhizoids formed equally well with red spotlight irradiation of three different parts of an end cell, i.e. distal end, middle, and proximal end, and with irradiation of centrifugal and centripetal end parts of a centrifuged end cell. The Pr distribution was confirmed with an experiment using far red irradiation over the entire cell, centrifugation, and red spotlight irradiation. The Pr-phytochrome molecules appeared to be mobile because no dichroic orientation was shown with polarized red spotlight irradiation. On the contrary, it is suggested that far red-absorbing form of phytochrome molecules are evacuated from the centripetal end part by the centrifugation in an experiment involving red irradiation over the entire cell-centrifugation-far red spot irradiation. Rhizoid formation was repressed markedly by far red irradiation of the centrifugal end part but not of the centripetal end part.     

Effects of Gamma-Irradiation on the Activity of Tonoplast H+-ATPase from Potato Tubers (Solanum tuberosum L.)

Tonoplast vesicles were prepared from potato tubers (Solariumtuberosum L.) on a step gradient (0% and 6%, w/w) of dextranT-70 to clarify the mechanism by which the tonoplast H⁺-ATPaseis inactivated by gamma-irradiation. H⁺-ATPase activity andH⁺ -pumping were examined after irradiation of tubers (in vivoirradiation) and of isolated tonoplast vesicles (in vitro irradiation)at doses up to 1.0 kGy. Both in vivo irradiation and in vitroirradiation resulted in significant decreases in ATPase andH⁺-pumping activities. The ATPase and H⁺-pumping activities12 h after irradiation were much lower than those 2 h afterirradiation. Solubilized H⁺-ATPase was inactivated, in a dose-dependentmanner, by irradiation (enzyme irradiation) to a greater extentthan was observed after in vitro irradiation or in vivo irradiation.The activity of ATPase 12 h after enzyme irradiation was almostthe same as it was 2 h after enzyme irradiation. The free fattyacid content of vacuolar membranes was increased by in vivoirradiation and by in vitro irradiation with an accompanyingdecrease in tonoplast H⁺-ATPase activity. Lipids from irradiatedtonoplasts had a considerable inhibitory effect on the activityof solubilized H⁺-ATPase. This result suggests that the directinactivation of H⁺-ATPase in potato tonoplast by gamma-irradiationis augmented by the effects of deterioration of membrane lipidsthat is induced by the irradiation. (Received December 21, 1994; Accepted May 16, 1994)     

Tissue damage after single high-dose intraoperative irradiation of the canine liver: evaluation in time by means of radionuclide imaging and light microscopy

To establish the tolerance of liver tissue to single high-dose intraoperative irradiation, the histopathological changes in the canine liver after single high-dose intraoperative irradiation were investigated by means of radionuclide imaging and light microscopy. Intraoperative irradiation at doses of 0, 10, 20, 25 or 30 Gy was applied to a part of the liver of 25 beagles. Radionuclide imaging using (99m)Tc-sulfur colloid was performed at several times during follow-up. Elective humane killing was done 3 months and 1, 2, 3 and 5 years after irradiation. Light microscopy was used to identify histopathological alterations. There was no morbidity or mortality during a maximal follow-up of 5 years. In 40% of the animals, a region of diminished uptake was observed at the irradiation site. The regions of diminished uptake of the radiopharmaceutical agent became smaller with time. Light microscopic examination revealed severe parenchymal fibrosis, liver cell atrophy, and bile duct proliferation at the irradiated area 1 to 2 years after irradiation. At 3 and 5 years, vascular changes with endothelial proliferation and focal arteriolar hyalinosis were observed. This study demonstrates that intraoperative irradiation of a part of the liver in the canine model can be applied safely. Light microscopy confirmed that histological damage was not always accompanied by diminished uptake of the radiopharmaceutical agent at the irradiation site.     

DNA-protein cross-links in cells of internal organs of rats after fractional irradiation at various doses

The influence of daily fractional irradiation of male Wistar rats for 30 days on DNA-protein cross-links (DPC) in spleen, thymus, and liver cells was studied. The level of DPC depended strongly on the daily dose of irradiation and the studied organ. After irradiation at dose 0.5 Gy per day increased DPC level was detected in all organs. The highest level was in the lymphoid organs and the lowest in the liver. After irradiation at dose 0.3 Gy per day DPC formation was detected only in the thymus. The data suggest the existence of a dose threshold for DPC formation during fractional irradiation.     

A model for assessing cognitive impairment after fractionated whole-brain irradiation in nonhuman primates

To investigate the effect of fractionated whole-brain irradiation on nonhuman primates, 6-9-year-old male rhesus monkeys were irradiated with 40 Gy delivered as two 5-Gy fractions/week for 4 weeks. Cognitive function was assessed 5 days/week for 4 months prior to fractionated whole-brain irradiation and for 11 months after irradiation using a Delayed-Match-to-Sample (DMS) task at both low and high cognitive loads. Local rates of cerebral glucose metabolism were measured prior to and 9 months after irradiation using [(18)F]-2-deoxy-2-fluoro-d-glucose positron emission tomography. Low cognitive load trials did not reveal a significant reduction in performance until 7 months after irradiation; performance then declined progressively. In high cognitive load trials, the initial impairment was observed ～1 month after irradiation. This was followed by a transient recovery period over the next 1-2 months, after which performance declined progressively through 11 months after irradiation. Nine months after irradiation, glucose uptake during the DMS task was decreased in the cuneate and prefrontal cortex and was increased in the cerebellum and thalamus compared with the levels prior to irradiation. Results from this pilot study suggest that the radiation-induced changes in cognition and brain metabolism observed in rhesus monkeys may be similar to those observed in brain tumor patients receiving brain irradiation.