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.     

The dynamics of cytogenetic anomalies output in seedling merysteme at the chronic irradiation of seeds

The dynamics of chromosomal aberrations in seedling root merysteme is explored in various terms of irradiation of two genotype corn dry seeds. The effects of chronic irradiation with low rate dose, with acute and with combined irradiation are explored in the different terms of seed storage. It is shown that the output of chromosomal aberrations and of the efficiency of irradiation (1/Gy) change depending on the accumulated dose of chronic irradiation and for both genotypes are described by unmonotonous functions. Efficiency of acute irradiation changes the dependence on the terms of seed storage. The efficiency of chronic irradiation considerably exceeds the efficiency of acute irradiation. Antagonistic effect of combined irradiation dry seeds of one of genotypes is marked.     

Effects of irradiation by the low-intensity electromagnetic field of the millimetric range on the Daphnia magna culture at various developmental stages

The influence of low-intensity electromagnetic irradiation and exposure to cadmium on survival and reproduction rates of daphnia in the process of their ontogenesis is investigated. The effects of the irradiation are clearly manifested in the toxicological experiments at coactions of the irradiation and cadmium and are weakly exhibited at action of the irradiation itself. At all stages of development, the irradiation does not influence the survival rate of daphnia. However, the irradiation increases their sensitivity to cadmium effects.     

Studies on the irradiation of toxins of Clostridium botulinum and Staphylococcus aureus

The effects of irradiation of Clostridium botulinum neurotoxin type A (BNTA) and staphylococcal enterotoxin A (SEA) in gelatin phosphate buffer and cooked mince beef slurries were investigated. Estimation of toxins by immunoassays showed that in buffer, toxins were destroyed by irradiation at 8.0 kGy; in mince slurries however, 45% of BTNA and 27–34% of SEA remained after this level of irradiation. At 23.7 kGy, over twice the dose of irradiation proposed for legal acceptance in the UK, 15% of BNTA and 16–26% of SEA still remained. Increasing concentrations of mince conferred increased protection against the effect of irradiation on both toxins. The biological activity of BNTA was more sensitive to irradiation than the immunological activity. Staphylococcal enterotoxin was more resistant to irradiation than BNTA. Irradiation should therefore only be used in conjunction with good manufacturing practices to prevent microbial proliferation and toxin production prior to irradiation.     

Studies on the irradiation of toxins of Clostridium botulinum and Staphylococcus aureus

The effects of irradiation of Clostridium botulinum neurotoxin type A (BNTA) and staphylococcal enterotoxin A (SEA) in gelatin phosphate buffer and cooked mince beef slurries were investigated. Estimation of toxins by immunoassays showed that in buffer, toxins were destroyed by irradiation at 8.0 kGy; in mince slurries however, 45% of BTNA and 27-34% of SEA remained after this level of irradiation. At 23.7 kGy, over twice the dose of irradiation proposed for legal acceptance in the UK, 15% of BNTA and 16-26% of SEA still remained. Increasing concentrations of mince conferred increased protection against the effect of irradiation on both toxins. The biological activity of BNTA was more sensitive to irradiation than the immunological activity. Staphylococcal enterotoxin was more resistant to irradiation than BNTA. Irradiation should therefore only be used in conjunction with good manufacturing practices to prevent microbial proliferation and toxin production prior to irradiation.     

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.     

Effect of gamma-irradiation on the molecular properties of myoglobin

To elucidate the effect of gamma-irradiation on the molecular properties of myoglobin, the secondary and tertiary structures, as well as the molecular weight size of the protein, were examined after irradiation at various irradiation doses. Gamma-irradiation of myoglobin solutions caused the disruption of the ordered structure of the protein molecules, as well as degradation, crosslinking, and aggregation of the polypeptide chains. A SDSPAGE study indicated that irradiation caused initial fragmentation of the proteins and subsequent aggregation, due to cross-linking of the protein molecules. The effect of irradiation on the protein was more significant at lower protein concentrations. Ascorbic acid protected against the degradation and aggregation of proteins by scavenging oxygen radicals that are produced by irradiation. A circular dichroism study showed that an increase of the irradiation decreased the alpha-helical content of myoglobin with a concurrent increase of the aperiodic structure content. Fluorescence spectroscopy indicated that irradiation increased the emission intensity that was excited at 280 nm.     

有机相中超声辐照对脂肪酶活性的影响

酶在有机相中的催化作用是８０年代以来酶工程学研究的热点之一．虽然酶在有机相中的催化反应有许多优点［１］,但在工业生产上的应用却很有限,这主要是有机相中的酶促反应速度太慢,反应周期太长之故．１９９１年Ｖｕｌｆｓｏｎ等报道了超声辐照对有机相中枯草蛋白酶催...     

The Evaluation of the Oxidant Injury as a Function of Time Following Brain Irradiation in a Rat Model

This study presents the evaluation of the oxidant injury as a function of time following brain irradiation in a rat model. Thirty-five Wistar rats were divided into seven groups. The rats in Group 1 through Group 6 underwent irradiation, whereas the rats in Group 7 underwent sham irradiation. The rats in Group 1 through Group 6 underwent euthanasia at 1 through 48 h following irradiation, whereas the rats in Group 7 underwent euthanasia immediately following sham irradiation. At the time of euthanasia, the brain tissue was dissected for evaluation of the malondialdehyde (MDA) level and the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSHPX) activities. The mean MDA levels were increased and the mean SOD, CAT and GSHPX activities were decreased at all of the time points for evaluation for the rats that underwent irradiation as compared to the rats that underwent sham irradiation, substantial for Group 1 and gradually leveling out through Group 6. This study confirms that the oxidant injury is evaluated at its best through the first several hours following brain irradiation.     

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)     

Radioprotective action of gas hypoxia (8%) in local irradiation of the kidneys]

The radioprotective action of hypoxia in local irradiation of kidneys was studied. The experiments were carried out on hybrid mice (CBA x C57Bl) exposed to local X-ray irradiation through a lead diaphragm matched to the kidneys. In the experimental group the animals breathed in gaseous mixture with 8% of oxygen prior to and during irradiation. 20-36 weeks after irradiation the functions of glomerular and juxtaglomerular systems, as well as mass of native and dried kidneys were studied in the animals. It is shown that hypoxia efficiently protects kidneys against irradiation and permits increasing the supplied dose of radiation at least by 25%. High-efficient protection is retained when passing from single to fractionated irradiation.     

Impact of X-ray irradiation as an equivalent alternative to gamma for sterilization of single-use bioprocessing polymers

Irradiation sterilization of polymeric pharmaceutical processing systems and medical devices, an essential healthcare technology, is facing critical business continuity challenges, driving the need to qualify equivalent alternative irradiation technologies, such as X-ray. Whereas the underlying there is a paucity of cross-industry published data evaluating X-ray irradiation effects on plastics as compared to gamma irradiation. That leads to regulatory uncertainty in the levels of costly validation data regulators will require and overall apprehension in the rate of X-ray irradiation adoption. The present study evaluates the impact of X-ray versus gamma irradiation on a wide range of polymers with more than 36 single-use (SU) components, using a comprehensive set of industry aligned methods for characterization of bioprocess polymers. Whereas many of these techniques readily demonstrate changes in polymer properties following irradiation, all of the polymers evaluated demonstrated that the impact of X-ray irradiation was to the same degree or less as compared to gamma. Increased publication of studies evaluating the impact to polymers of X-ray versus gamma irradiation is critical to leveraging extensive, existing validation packages on bioprocess systems and medical devices obtained following gamma irradiation, and essential in qualifying X-ray irradiation as an equivalent technology (i.e., materials are impacted to the same extent or less than gamma) that can overcome business continuity challenges to ensure continued availability of critical patient therapies.     

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.     

Synergetic effect of freeze-drying and gamma irradiation on the mechanical properties of human cancellous bone

Freeze-drying and irradiation are common process used by tissue banks to preserve and sterilize bone allografts. Freeze dried irradiated bone is known to be more brittle. Whether bone brittleness is due to irradiation alone, temperature during irradiation or to a synergetic effect of the freeze-drying-irradiation process was not yet assessed. Using a left–right femoral head symmetry model, 822 compression tests were performed to assess the influence of sequences of a 25 kGy irradiation with and without freeze-drying compared to the unprocessed counterpart. Irradiation of frozen bone did not cause any significant reduction in ultimate strength, stiffness and work to failure. The addition of the freeze-drying process before or after irradiation resulted in a mean drop of 35 and 31% in ultimate strength, 14 and 37% in stiffness and 46 and 37% in work to failure. Unlike irradiation at room temperature, irradiation under dry ice of solvent–detergent treated bone seemed to have no detrimental effect on mechanical properties of cancellous bone. Freeze-drying bone without irradiation had no influence on mechanical parameters, but the addition of irradiation to the freeze-drying step or the reverse sequence showed a detrimental effect and supports the idea of a negative synergetic effect of both procedures. These findings may have important implications for bone banking.     

Treatment of overt meningeal leukaemia in children: results of second MRC meningeal leukaemia trial.

After induction ofmeningeal remission by a course of intrathecal methotrexate patients were randomly allocated to receive either cranial irradiation or craniospinal irradiation. Patients being treated for their first meningeal relapse were randomised separately from those in their second or subsequent relapse. All eight patients in their first relapse who were given cranial irradiation alone developed further meningeal recurrence (median length of remission 15 weeks) compared with only two out of nine given craniospinal irradiation (median length of remission at least 99 weeks). Four of the nine patients given craniospinal irradiation were alive and without further meningeal relapse two and a half to four years after treatment. Craniospinal irradiation produced no such advantage for patients entering the trial in their second or subsequent meningeal relapse.     

Effects of irradiation on the reproductive ability of Zonitoides arboreus, a snail pest of orchid roots

The effect of irradiation on the reproductive ability of the orchid snail, Zonitoides arboreus, a serious pest of potted orchids in Hawaii, was investigated. Weekly egg production averaged between 0.8 and 1.9 over a 9–wk period for snails not exposed to irradiation, and egg hatch averaged 61%. In comparison to untreated controls, irradiation of snails at the lowest dose tested (34–37 Gy) reduced egg production and egg hatch by 63% and 94%, respectively over a 9–wk period. None of the snails treated with levels of irradiation ≥ 69 Gy produced viable eggs. This is the first study measuring the effect of ionising irradiation on a terrestrial snail or slug species using sterilising doses. Overall, the results show that the reproductive ability of this snail species is affected by irradiation in a similar manner as for Biomphalaria glabrata, an aquatic snail for which the effects of irradiation have been studied in detail.     

Effect and aftereffect of gamma radiation pretreatment on enzymatic hydrolysis of wheat straw

Irradiation pretreatment of wheat straw was carried out at different doses by using Co-60 gamma radiation. The weight loss and fragility of wheat straw after irradiation, the combination effect of irradiation and mechanical crushing on enzymatic hydrolysis of wheat straw as well as the aftereffect of irradiation were examined. It is shown that irradiation can cause significant breakdown of the structure of wheat straw. The weight loss of wheat straw increased and the size distribution after crushing moved to fine particles at elevated irradiation doses. The glucose yield of enzymatic hydrolysis of wheat straw increased with increasing doses and achieved the maximum (13.40%) at 500 kGy. A synergistic effect between irradiation and crushing was observed, with a glucose yield of 10.24% at a dose of 500 kGy with powder of 140 mesh. The aftereffect of irradiation had important impact on enzymatic hydrolysis of wheat straw. The aftereffect (at 22nd day) of 400 kGy irradiation accounted for 20.0% of the initial effect for glucose production, and the aftereffects of 50, 100, 200 (at 9th day) and 300 kGy (at 20th day) accounted for 12.9%, 14.9%, 8.9% and 9.1%, respectively, for reducing sugar production.     

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.     

The genome instability in the descendants of the Chinese hamster of the cells, irradiated by the low dose and by various intensities of gamma-radiation

The V-79 Chinese hamster cells were irradiated by gamma-rays in dose of 0.5 Gy at powers of doses 0.48 Gy/min (an acute irradiation) and 0.0485 MGy/min (a prolonged irradiation). The acute and prolonged irradiation in a dose of 0.5 Gy enlarges frequency of the appearance of micronucleus (MN). Subsequent cultivation of the irradiated cells during 20 generations enlarges frequency of MN, and for prolonged an irradiation the boosted frequency of MN, is saved during 40-60 generations. After an acute irradiation the number of MN starts to reduce after 20 doublings.