Low-background radiation measurements on video display terminals.
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[Manifestation of the radiation aftereffects in daughter generations of barley grown under an increased natural radiation background].
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Edible Grain↗
Background radiation.
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Cosmic Radiation↗
Background radiation paradoxes.
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Dose-Response Relationship, Radiation↗
[Disorders of interferon status in bronchopulmonary diseases in children living under conditions of elevated background radiation].
Impairments in the interferon status of children with chronic and recurring diseases of the respiratory organs were investigated and its correction was shown possible with the use of alpha 2-interferon (reaferon). Suppression of the interferon-producing capacity of the immunocytes was observed in all the cases of the disease aggravation. The level of the suppression correlated with the severity of the infection. In the patients affected by radiation the suppression of the interferonogenesis was more marked. However, in these cases no dependence of the detected impairments in the interferon status on the level of the radiation pollution of the territory of the children residence was shown. The inclusion of reaferon to the basal therapy resulted in a significant increase of the alpha-interferon production in the cases of bronchial asthma and asthmatic bronchitis as well as its recovery to the normal in the cases of recurring bronchitis and chronic pneumonia. In all the cases of bronchopulmonary diseases only a tendency towards normalization of the alpha-interferon indices was recorded.
Bronchial Diseases↗
[The immunocorrection with Aerosil-350 of the natural resistance of mice found under conditions of an elevated radiation background].
Experiments on the CBA mice that had been within 30 km of the Chernobyl NPP accident for 3 months revealed a decrease in the phagocytic and bactericidal properties of peritoneal macrophages accompanied with a disturbance in the production of interleukin-1 and a tumor necrosis factor responsible for the cell immunity. A single administration of a silicon-containing enterosorbent Aerosil-350 expedient to remove radionuclides and ensure the organism detoxication made it possible to correct and restore the affected cell and organism immunity for 7 days.
Administration, Oral↗
Postradiation sarcoma: case report and review of the potential complications of therapeutic ionizing radiation.
BACKGROUND: Radiation therapy is an acceptable treatment choice for many cutaneous malignancies. A potential late sequela of ionizing radiation is the development of secondary neoplasms within the treatment field. Although there are well-known cutaneous syndromes in which the use of ionizing radiation is contraindicated, in other clinical situations, physicians may not fully realize the risks associated with this therapeutic modality. OBJECTIVE: Through a case report presentation, a potential adverse consequence of radiation therapy will be discussed. A subsequent review of the literature should allow clinicians to better understand the potential risks of therapeutic radiation. METHODS: A case report and review of the literature are provided. RESULTS: A healthy black male with an unusual distribution of lower extremity squamous cell carcinomas in situ developed a malignant fibrous histiocytoma after radiation therapy. CONCLUSION: Postradiation sarcomas are uncommon complications of radiation therapy; however, the significant metastatic capabilities of these tumors demand that clinicians be aware of the potential risks of primary radiation therapy in the treatment of cutaneous tumors.
Adult↗
Hormesis: an adaptive expectation with emphasis on ionizing radiation.
Non-linear fitness gradients with maxima between extremes are expected for any environmental variable to which free-living populations are exposed. For exceedingly toxic agents, including ionizing radiation, such deviations from linearity are close to zero exposure and are conventionally called hormesis. Accordingly, hormesis is an extreme version of the non-linear fitness gradients for general environmental stresses such as temperature fluctuations, for which maximum fitness occurs at the moderate temperature fluctuations to which free-living populations are most commonly exposed. Some metabolic reserves should occur under moderate temperature stresses because of the need for pre-adaptation enabling survival during exposure to occasional periods of more extreme stress, especially at species borders where selection for stress resistance is likely to be most intense. Because heat shock proteins are induced by all stresses, adaptation to extreme temperatures should translate into adaptation to other stresses. Consequently, metabolic reserves from adaptation to extreme temperatures in the past should translate into protection from correlated abiotic stresses, especially in human populations where modern cultural processes are now ameliorating exposure to extreme stresses. Ambient and man-made radiations of non-catastrophic dimensions should therefore lead to stress-derived radiation hormesis. Other stresses can, in principle, be incorporated into this model. Accordingly, evolutionary and ecological considerations suggest two components of hormesis in relation to ionizing radiation: background radiation hormesis based upon the background exposure to which all organisms on earth are subjected; and stress-derived radiation hormesis. Exposure under stress-derived radiation hormesis is considerably larger than under background radiation hormesis, so significant deleterious effects from non-catastrophic radiation normally may be impossible to detect. Suggestions are provided for testing such postulated deviations from the commonly assumed linear no-threshold (LNT) hypothesis for the biological consequences of exposure to radiation.
Adaptation, Physiological↗
The properties of gamma-radiation and high-energy neutron fluxes in "MIR" station orbit.
The study of radiation background components in the near-Earth space is very important for different branches of space research, in particular for space dosimetry and for the planning of gamma-astronomy experiments. Detailed information on the neutral components (gamma-quanta, neutrons) of background radiation was obtained during the Grif-1 experiment onboard Mir orbital station (OS). The measurements of fluxes of 0.05-50 MeV gamma-quanta and >30 MeV neutrons with a large area instrument (approximately 250 cm2 for gamma-quanta, approximately 30 cm2 for neutrons) as well as corresponding charged particle measurements (0.4-1.5 MeV electrons, 1-200 MeV protons) were made during this experiment. The background components induced by the station's own radiation as well as the albedo gamma-rays from the Earth's atmosphere were revealed as the result of data analysis for about 600 h of observation. A mathematical model describing the latitude and energy dependences of atmospheric albedo gamma-rays as well as of those of gamma-quanta produced in the material of the station due to cosmic ray interactions was developed. An analytical approximation of the spectrum of induced gamma-rays from radioactive isotopes stored in the station and instrument's materials is presented. The dynamics of gamma-quantum background fluxes during the geomagnetic disturbances of January 10-11, 1997 are discussed. An analytical representation of the latitude dependence of the integral flux of neutrons with >30 MeV is given.
Brazil↗
[The structure of the morbidity and disability among miners who worked in the cleanup of the aftereffects of the accident at the Chernobyl Atomic Electric Power Station].
The authors analyzed morbidity and invalidity in miners engaged in liquidation of Chernobyl disaster sequels depending on the duration of stay in increased radiation background, radiation dose, length of work in the mines. Among the nosological entities prevailed vegeto-vascular dystonia, thyroid and gastrointestinal pathology.
Accidents, Occupational↗
Comparison of stages I-II thymoma treated by complete resection with or without adjuvant radiation.
BACKGROUND: Adjuvant radiation after resection of Masaoka stage II thymoma is widely advocated, but the evidence supporting it is controversial. Studies addressing this issue generally report few patients and lump all patients beyond stage I together in the analysis. METHODS: We retrospectively compared outcomes of stage I and II thymomas treated by resection alone with thymomas treated by resection plus radiation. Histology was re-reviewed to confirm pathologic staging and resection margin status. RESULTS: Between February 1992 and 2002, we performed 167 resections for thymoma. Of these, 70 patients were believed to have tumors in stage IIb or less intraoperatively, and all of these patients underwent complete resection. We reviewed the histopathology of 62 of 70 patients. Thirty thymomas demonstrated less than complete transcapsular microscopic invasion (stage I) and 40 thymomas demonstrated microscopic transcapsular invasion or macroscopic invasion into surrounding fatty tissue (stage II). Forty-seven patients underwent surgery without postoperative mediastinal radiotherapy. Dosages in the 23 radiated patients (3 stage I and 20 stage II) consisted of 45 to 55 Gy. Median follow-up was 70.3 months. Stage II patients who were radiated (n = 20) and those who were not radiated (n = 20) consisted of identical proportions in stages IIa and IIb. Two patients recurred (1 unradiated stage I patient and 1 radiated stage IIb patient). Overall 5-year survival rate was 91%. All who died were free of recurrence at time of death. Log-rank test showed no difference in Kaplan Meier survival curves (p = 0.32) between the radiated and unradiated groups. CONCLUSIONS: These data support the contention that margin-negative surgical resection alone is sufficient treatment for both stages I and II thymoma.
Adult↗
High-resolution macromolecular structure determination using CCD detectors and synchrotron radiation.
BACKGROUND: Synchrotron radiation sources have made impressive contributions to macromolecular crystallography. The delay in development of appropriate X-ray detectors has, however, been a significant limitation to their efficient use. New technologies, based on charge-coupled devices (CCDs), provide capabilities for faster, more accurate, automated data collection. RESULTS: A CCD-based X-ray detector has been developed for use in macromolecular crystallography and has been in operation for about one and a half years at the Cornell High Energy Synchrotron Source. It has been used for a variety of crystallographic projects, including a number of high-resolution structural studies. The statistical quality of the data, the detector's ease and efficiency of use, and the growing number of structural results illustrate the practical utility of this new detector system. CONCLUSIONS: The new detector has enhanced capabilities for measuring diffraction patterns from crystals of macromolecules, especially at high resolution, when the X-ray intensities are weak. The survey of results described here ranges from virus crystallography to weakly diffracting small-molecule structure determination and demonstrates the potential of CCD detectors when combined with synchrotron radiation sources.
Amino Acid Sequence↗
Skin infections in renal transplant recipients and the relation with solar ultraviolet radiation.
BACKGROUND: Ultraviolet radiation (UVR) is an important risk factor for skin cancer in transplant recipients. In view of the potential suppressive effect of UVR on host resistance it was examined whether exposure to UVR was also associated with the occurrence of various skin infections. METHODS: In a cohort of renal transplant recipients (n = 137), lifetime exposure was assessed by means of a retrospective questionnaire on cumulative sunlight exposure. Diagnosed skin infections since renal transplantation were extracted from the patient's medical charts. Season of diagnosis was regarded as indicative of short-term exposure. RESULTS: In comparison with winter a high rate of herpes simplex infections was found in spring [rate ratio (RR) = 4.09, 95% confidence interval (CI) 1.2-14.5], and high rates of herpes zoster infections (RR = 1.6, 95% CI: 0.8-3.5) and fungal/yeast infections in summer (RR = 2.1, 95% CI: 1.3-3.4). A higher lifetime exposure (RR = 2.31, 95% CI: 1.04-5.1) and a greater cumulative number of reported sunburns (RR = 2.3, 95% CI: 1.1-5.1) were independently associated with a higher risk of bacterial infections. CONCLUSIONS: The seasonal association with the occurrence of clinical herpes infections indicates an effect of short-term UVR. Our data suggest that the number of sunburn episodes in the past is also relevant for the susceptibility to certain skin infections.
Candidiasis, Cutaneous↗
The expression of p53, p21, Bax and induction of apoptosis in normal volunteers in response to different doses of ultraviolet radiation.
BACKGROUND: Ultraviolet radiation (UVR) damages keratinocytes. Direct DNA damage may undergo enzymatic repair followed by resumption of the normal cell cycle. Cells may also be eliminated without inflammation by the error-free process of programmed cell death or apoptosis. Necrosis of cells can occur after overwhelming damage. Failure of apoptosis leads to retention of cells with persistent mutations. OBJECTIVES: This study investigates p53-dependent apoptotic responses in normal skin following solar-simulated radiation (SSR). METHODS: Sun-protected buttock skin from normal volunteers with no history or clinical evidence of skin cancer was exposed to graded doses of SSR, 0.5, 1, 2 and 3 times the minimal erythema dose (MED). Biopsies taken at a range of time points (4.5, 9, 24, 33, 48 and 72 h) after UVR, quantified the time course and dose-response of apoptosis and the expression of the relevant proteins, p53, p21waf1/Cip1 and Bax, by single and double labelling techniques. RESULTS: Apoptosis was upregulated in a dose-dependent manner as was the expression of p53, p21waf1/Cip1 and Bax in response to SSR. Following exposure to 3 MEDs it was found that: (i) the maximum number of apoptotic cells occurred at 48 h; (ii) p53 protein expression was upregulated from 4 to 72 h preceding peak p21waf1/Cip1 protein expression (9-48 h) and peak Bax protein expression (33 h). CONCLUSIONS: These results suggest that, following SSR, normal human skin induces apoptosis by the p53, p21waf1/Cip1, Bax pathway in vivo. In addition, induction of apoptosis and expression of p53, p21waf1/Cip1 and Bax occurs in a dose-dependent manner.
Aged↗
Repeat intracoronary radiation for recurrent in-stent restenosis in patients who failed intracoronary radiation.
BACKGROUND: Intracoronary radiation therapy (IRT) is the only proven treatment for in-stent restenosis (ISR). It is, however, associated with a significant failure rate. The present study evaluated the outcomes of patients who underwent repeat intracoronary radiation for recurrent ISR. METHODS AND RESULTS: Fifty-one consecutive patients who failed a previous radiation treatment, presented with angina and angiographic evidence of ISR, and were treated with percutaneous coronary intervention (PCI) and repeat radiation to the same segment were studied. Twenty-five patients were treated with gamma radiation in a dose of 15 Gy, and 26 were treated with beta radiation doses of 18.3 to 23 Gy. The mean cumulative dose for this cohort was 39.5+/-11.9 Gy (range, 29 to 75.6 Gy). The outcomes of those patients were compared with outcomes of 299 patients who also failed initial radiation but were treated with repeat conventional PCI to a previously irradiated segment without repeat radiation. At 9 months after treatment, the repeat-IRT group had lower rates of target lesion revascularization (23.5% versus 54.6%; P<0.001) and major adverse cardiac events, including target vessel revascularization (29.4% versus 61.3%; P<0.001). At 9 months, patients with repeat IRT were free of angiographic and clinical events related to the radiation therapy. CONCLUSIONS: Repeat gamma or beta radiation to treat failed IRT for ISR after conventional PCI is safe and effective at 9 months and should be considered as a therapeutic option for this difficult patient subset.
Angina Pectoris↗
Diosmectite (DIOSMECTAL) in preventive anti-diarrheic therapy in patients subjected to pelvic radiation.
BACKGROUND: The radiation therapy of abdominal-pelvic tumors, determining diarrhea and cramps, could reduce the compliance of the patient and compromise his quality of life. This study attempts to assess the effects of adjuvant therapy with diosmectite (Diosmectal) on the above mentioned side effects from radiotherapy. METHODS: From August 1998 to September 1999, 40 patients (mean age 68) at the Oncological Radiotherapy Division of the Azienda Policlinico of Modena took part in the study: 21 forming the group of patients treated with diosmectite and 19 forming the control group. The radiotherapy was administered with total doses varying from 45 to 70 Gy in both groups with daily doses of 1.8-2 Gy. From the beginning of the therapy the patients in the group treated with Diosmectal, received 6 g daily doses of the drug split into two administrations. The diarrhea was assessed by referring to the Lent Soma score. RESULTS: In the group of patients not in therapy, an incidence of diarrhea was observed in 77% of subjects while in the group in therapy the incidence of diarrhea dropped to 25% of the cases (p<0.005), with an increase in the latency of the appearance of any diarrhoeic symptoms. CONCLUSIONS: Our data suggests that the administration of diosmectite in a prophylactic manner is capable of reducing the incidence of gastroenteric symptomatology (diarrhea and cramps).
Journal Article↗
Combination with CD/5-FC gene therapy enhances killing of human bladder-cancer cells by radiation.
BACKGROUND: Resistance to radiation and chemotherapy is a significant obstacle to the treatment of advanced bladder cancer. Gene therapy combined with radiation represents a new approach to cancer treatment. In the present study, we investigated whether adenovirally directed, cytosine deaminase (CD)/5-fluorocytosine (5-FC) gene therapy could induce cell toxicity and radiosensitization through the intracellular production of 5-fluorouracil (5-FU) in bladder-cancer cells. METHODS: Three human bladder-cancer cell lines, KK47 (wild-type p53+), T24 (p53 mutated) and 5637 (p53 mutated), were investigated. A recombinant adenovirus vector containing the CD gene (Ad-RSV-CD) was used. Cells were infected with Ad-RSV-CD and treated with 5-FC. Forty-eight hours after infection, the cells were irradiated and cytotoxicity assays performed to determine the extent of increase in in vitro cytotoxicity. A KK47 subcutaneous tumor-xenografts model was used in an animal study to examine the tumor growth inhibitory effect of this combination therapy. Ad-RSV-CD was directly injected into the tumor and daily 5-FC was intraperitoneally injected. Forty-eight hours after injection of Ad-RSV-CD, the tumor was irradiated. The tumor volume was measured every day. RESULTS: In all three cell lines, the combination treatment enhanced the cell killing of human bladder-cancer cells in vitro. It also enhanced the tumor-growth inhibition in the KK47 tumor model. CONCLUSIONS: In the present study, we demonstrated that CD/5-FC gene therapy combined with radiation therapy enhances cell killing of human bladder-cancer cells in in vitro and in vivo animal models.
Adenoviridae↗
Natural radioactivity and radiation exposure in the high background area at Chhatrapur beach placer deposit of Orissa, India.
A high natural background radiation area is reported for the Chhatrapur beach placer deposit of Orissa state, on the southeastern coast of India, due to the presence of radiogenic heavy minerals. The average activity concentrations of radioactive elements 232Th, 238U and 40K were measured by gamma-ray spectrometry using a HPGe detector, and found to be 2500 +/-1850, 230 +/- 140 and 120 +/- 35 Bq kg-1, respectively, for the bulk sand samples. The absorbed gamma dose rates in air due to the naturally occurring radionuclides varied from 375 to 5000 nGy h-1, with an average value of 1625 +/- 1200 nGy h-1. The external annual effective dose rate of the region ranged from 0.46 to 6.12 mSv y-1, with an average value of 1625 +/- 1200 mSv y-1. The absorbed gamma dose rate levels of Chhatrapur beach area were similar to the monazite sand-bearing high background radiation areas of southern and southwestern coastal tracts of India and other similar areas of the world. The major contributors to the enhanced level of radiation are monazite and zircon sands.
Environmental Exposure↗