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In vivo exposition of guinea pig epidermal cells to infra-red irradiation (IR) led to significant, biphasic reduction of the proliferating activity after 6 h and 72 h. Not before 168 h after exposure, the proliferating activity rose above the normal rate. The quantitative alterations of DNA-proliferating cells went along with prolongation of the S-phase and the cell cycle. UV-irradiated cells react earlier by reduction of the DNA-proliferating activity directly followed by stages of hyperproliferation.
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The purpose of this study was to determine the relationship between the biologic character of laryngeal carcinoma and the effects of radiation therapy. Using monoclonal antibody for p53 gene protein, 73 cases of laryngeal carcinoma were stained by the immunohistochemical DACO CSA System method. Results of the stain can be divided into intense, moderate and negative expression. There is a significant relationship between the gene expression and radiation effect. We found that samples which had higher level of staining due to increased gene expression, were affected more by the radiation therapy. The p53 gene expression can be useful in predicting the outcome of laryngeal carcinoma and be helpful in clinical therapy.
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This paper presents so-called radiation effectiveness factors that are intended to represent the biological effectiveness of different radiation types, relative to high-energy Co gamma rays, for the purpose of estimating cancer risks and probability of causation of radiogenic cancers in identified individuals. Radiation effectiveness factors are expressed as subjective probability distributions to represent uncertainty that arises from uncertainties in estimates of relative biological effectiveness obtained from radiobiological studies of stochastic endpoints, limited data on biological effectiveness obtained from human epidemiological studies, and other judgments involved in evaluating the applicability of available information to induction of cancers in humans. Primarily on the basis of reviews and evaluations of available data by experts, probability distributions of radiation effectiveness factors are developed for the following radiation types: neutrons of energy less than 10 keV, 10-100 keV, 0.1-2 MeV (including fission neutrons), 2-20 MeV, and greater than 20 MeV; alpha particles of any energy emitted by radionuclides; photons of energy 30-250 keV and less than 30 keV; and electrons of energy less than 15 keV. Photons of energy greater than 250 keV and electrons of energy greater than 15 keV are assumed to have the same biological effectiveness as reference Co gamma rays and are assigned a radiation effectiveness factor of unity, without uncertainty. For neutrons and alpha particles, separate probability distributions of radiation effectiveness factors are developed for solid tumors and leukemias, and small corrections to represent an inverse dose-rate effect are applied to those distributions in cases of chronic exposure. A radiation effectiveness factor different from unity for 15-60 keV electrons is discussed but is not adopted due to a lack of relevant radiobiological data. Radiation effectiveness factors presented in this paper are incorporated in the Interactive RadioEpidemiological Program and were developed for use by The National Institute for Occupational Safety and Health and U.S. Department of Labor in evaluating claims for compensation for radiogenic cancers by workers at U.S. Department of Energy facilities.
Radiation effects on macromolecular synthesis essential for the Chinese hamster cell to traverse the life cycle and to divide have been investigated. Life-cycle analysis techniques employing inhibitors of macromolecular synthesis were used in determining the kinetics of cell growth for specific segments of the population following spontaneous recovery from radiation-induced division delay. The results indicated that recovery does not occur in the absence of functional protein synthesis. Under conditions which inhibit normal RNA and DNA synthesis, irradiated cells can recover the capacity to traverse the life cycle and to divide. The stability of mRNA species coding for proteins essential for division in irradiated cells was also measured. The mean functional lifetime of these mRNA species was 1 hr. The data demonstrate the existence of a specific segment of the population consisting of cells which have completed transcription related to division but not concomitant translation and which can recover from the radiation injury without synthesis of additional RNA. Thus, initial recovery of the ability to divide has an obligate requirement for protein synthesis but no corresponding requirement for nucleic acid synthesis during the period when original messenger remains intact.
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OBJECT: The prognostic value of differentiating between recurrent malignant glioma and a lesion due to radiation effect by performing stereotactic biopsy has not been assessed. Thus, this study was undertaken to determine such value. METHODS: Between 1995 and 2001, 114 patients underwent magnetic resonance (MR) imaging-guided stereotactic biopsy to differentiate lesions caused by a recurrence of malignant astrocytoma and by radiation effect. All patients had previously undergone tumor resection (World Health Organization Grade III or IV) followed by radiotherapy. Disease diagnosis based on biopsy and patient characteristics were assessed as predictors of survival according to results of a multivariate Cox regression analysis. The diagnosis determined with the aid of biopsy was compared with that established during a subsequent resection in 26 patients. Survival following stereotactic biopsy was markedly increased in patients suffering from radiation effect compared with those harboring recurrent malignant glioma (p < 0.0001). In patients with radiation effect on biopsy, an increasing patient age (p < 0.05), having had two compared with one prior resection (p < 0.05), and a decreasing time from radiotherapy to biopsy (p < 0.001) were factors associated with decreased survival. Nevertheless, in patients with biopsy-defined radiation effect at second progression or with an age younger than 50 years the survival rate remained higher than that in patients with recurrent tumor on biopsy (p < 0.01). A biopsy-based diagnosis of radiation effect obtained less than 5 months after radiotherapy was not associated with an increased rate of patient survival compared with a diagnosis of recurrent malignant glioma on biopsy (p = 0.286). Eighty-six percent of lesions initially determined to be due to radiation effect on biopsy fewer than 5 months after radiotherapy were characterized as recurrent glioma by a mean of 11 months later. In contrast, only 25% of lesions initially diagnosed as attributable to radiation effect on biopsy more than 5 months after radiotherapy were classified as recurrent glioma a mean of 12 months later (p < 0.05). CONCLUSIONS: With the aid of stereotactic biopsy the authors demonstrated prognostic significance in differentiating recurrent malignant astrocytoma from a lesion due to radiation effect in patients presenting more than 5 months after having undergone radiotherapy. In patients who presented earlier than 5 months after radiotherapy, radiation effect on biopsy was not associated with an improved rate of survival compared with that in patients harboring recurrent malignant astrocytoma.
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The paper presents data on radiation effects in populations of wild vertebrate animals inhabiting contaminated terrestrial ecosystems. The data were extracted from the database "Radiation effects on biota", compiled within the framework of the EC Project EPIC (2000-2003). The data collection, based on publications in Russian, demonstrates radiation effects in the areas characterized with high levels of radionuclides (Kyshtym radioactive trace; "spots" of enhanced natural radioactivity in the Komi region of Russia; territories contaminated from the Chernobyl fallout). The data covers a wide range of exposures from acute accidental irradiation to lifetime exposures at relatively low dose rates. Radiation effects include mortality, changes in reproduction, decrease of health, ecological effects, cytogenetic effects, adaptation to radiation, and others. Peculiarities of radiation effects caused by different radionuclides are described, also the severity of effects as they appear in different organisms (e.g. mice, frogs, birds, etc.).
The effect of radiation on tumor tissue can be optimized by adding radiosensitizing agents, in order to achieve a greater degree of tumor damage than expected from the use of either treatment alone. The ethanolic extract of Aphanamixis polystachya (APE) was tested in Swiss albino mice transplanted with Ehrlich ascites carcinoma (EAC) and exposed to various doses of gamma-radiation. EAC mice received 0, 10, 25, 50, 75, 100, 150 or 200 mg/kg body wt APE before exposure to 6 Gy gamma-radiation followed by once daily administration for another 8 consecutive days post-irradiation. The optimum radiosensitizing dose was found to be 50 mg/kg APE that was further tested in EAC mice exposed to 0, 1, 2, 4, 6 or 8 Gy hemi body gamma-radiation. The best effect of APE and radiation was observed for 6 Gy gamma-radiation. The splitting of 50 mg into two equal fractions of 25 mg and administering the split dose with a gap of 8 h on 1, 3, 5, 7 or 9 d of tumor inoculation resulted in an increased survival even when the drug was administered at late stages (day 5) of tumor development. The APE treatment before irradiation elevated lipid peroxidation followed by a reduction in the glutathione contents. Treatment of tumor bearing mice with APE before irradiation further reduced the activities of various antioxidant enzymes like glutathione peroxidase, glutathione-s-transferase, superoxide dismutase and catalase at different post last drug administration (PLDA) times.
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Recent reports indicating that tumor necrosis factor-alpha (TNF-alpha) can augment the lethal effects of radiation against certain tumor cell lines prompted us to investigate whether this premise holds true for human colon tumor xenotransplants. Nude mice implanted s.c. with LS174T adenocarcinoma cells (day 0) were randomized into 4 groups: 1) no treatment; 2) TNF-alpha at 1 x 10(4) units/i.v. injection on days 1, 4, 8, and 10; 3) radiation at 4 Gy delivered on days 2, 5, 9, and 11; and 4) TNF-alpha + radiation administered using the same time-dose schedules as for groups 2 and 3. A decrease in tumor growth was obtained with radiation, but not TNF-alpha, as a single modality. However, significanty slower tumor growth was observed with TNF-alpha + radiation when compared to radiation alone. Blood and spleen cells from animals receiving both modalities exhibited the highest oxidative burst capacity. Histopathological evaluation showed large areas of necrosis in animals treated with radiation and with combined radiation + TNF-alpha, and only small areas of necrosis in animals treated with TNF-alpha alone. Necrosis in TNF-alpha-treated animals was not significantly larger than in controls. Irradiation of LS174T cells in culture generally decreased soluble TNF-alpha receptor and carcinoembryonic antigen in cell supernatants, but TNF-alpha was not detectable, regardless of radiation. The results show that pretreatment with TNF-alpha can significantly enhance the effects of radiation against human colon tumor xenografts and that the mechanisms of action may be related to increased oxygen radical production when both agents are administered and/or to induction of apoptosis by TNF-alpha. This data provides support for further investigations using TNF-alpha as an adjunctive agent in the radiotherapy of colon and other cancers.
A study was made of a possibility to use immunological methods (the leucocyte migration inhibition test, leukergia reaction, the test of the cold fixation of the complement with cerebral antigen) for the assessment of neurotoxic and neuroradiation effects in total therapeutic irradiation of man at a dose of 10 Gy with preceding polychemotherapy. A rapid development of agranulocytosis made cellular reactions impossible. The above effects could be assessed using humoral specific immunological reactions. A possible role of anticerebral antibodies in the pathogenesis of neurological disorders was discussed.