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[en] The selective proteolytic pathway, dependent upon 'N-end rule' protein recognition/ubiquitination and on the subsequent proteasome dependent processing of ubiquitin conjugates, operates in apoptosis induced by γ-irradiation. The proteasome inhibitor peptide aldehyde, MG132, efficiently induced apoptosis and was also able (at doses lower than those required for apoptosis induction) to potentiate apoptosis induced by DNA damage. Its specificity is suggested by the induction of the ubiquitin (UbB and UbC) and E1 (ubiquitin activating enzyme) genes and by an altered ubiquitination pattern. More selectively, a di-peptide competitor of the 'N-end rule' of ubiquitin dependent protein processing inhibited radiation induced apoptosis. This inhibition is also followed by an altered ubiquitination pattern and by activation of Poly (ADP-ribose) polymerase (PARP). These data strongly suggest that early apoptosis radiation induced events are controlled by ubiquitin-dependent proteolytic processing. (author)
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[en] Short communication
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[en] An immunohistochemical analysis was carried out in order to characterize the phenotypic modifications induced by γ-rays in human skin and to study the expression of some growth factors and growth factor receptors. Following radiotherapy for breast carcinoma, dermal fibroblasts of mammary skin are located superficially near the dermo-epidermal junction. They exhibit either vimentin-positive/smooth muscle cells (SMC) α-actin-negative quiescent phenotype or vimentin-positive/SMC α-actin-positive 'reactive' myofibroblastic phenotype but no desmin intermediate filaments. Using two polyclonal antibodies against Transforming Growth Factor β (TGFβ), we observed a specific intranuclear staining in fibroblasts and epidermal cells. Epidermal Growth Factor-Receptors (EGFR) were detected as membrane-associated in all the epidermal cell layers of irradiated skin and this pattern appears strongly associated with previous irradiation. These data suggest that complex cellular interactions are involved between epidermal and dermal cells and with extracellular matrix components, mediated by various cytokines, including TGFβ and EGF-like factors
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[en] Since 1951, 236 patients who had received accidental irradiation have been examined and successfully treated by the Service of Radiopathology at the Institut Curie. Of these, 65 presented with very severe pathology following acute localised irradiation. The diversity in the circumstances of exposure led to a wide spectrum of clinical changes which permitted a semeiological analysis of this specific pathology. The basic physical and functional symptomatology (erythema, oedema, exudative dermatitis, necrosis, sclerosis, early sensation of heat and pain) and the main clinical types of damage (evolutive and aetiological) are described. (author)
Source
Jammet, H. (CEA Centre d'Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire); Daburon, F. (CEA, 78 - Jouy-en-Josas (France). Lab. Etable de Radiobiologie Appliquee); Gerber, G.B. (Commission of the European Communities, Brussels (Belgium). Directorate General for Research, Science and Development); Hopewell, J.W. (Oxford Univ. (UK)); Haybittle, J.L.; Whitfield, L. (eds.); British Inst. of Radiology, London; Br. J. Radiol; (suppl. no. 19); 159 p; ISBN 0-905749-13-8; 
; 1986; p. 12-15; British Institute of Radiology; London (UK); Workshop on radiation damage to skin: fundamental and practical aspects; Saclay (France); 9-11 Oct 1985; Price Pound18.00
; 1986; p. 12-15; British Institute of Radiology; London (UK); Workshop on radiation damage to skin: fundamental and practical aspects; Saclay (France); 9-11 Oct 1985; Price Pound18.00
[en] Fluorimetric analysis of DNA unwinding, which allows measurement of DNA strand breaks in human leukocytes, has been optimized by reducing the amount of cells required for the test and by modifying the DNA alkali unwinding conditions. The permitted measurement of DNA strand-break induction in cells irradiated with low (0.5-7 Gy) or high doses (5-20 Gy) of γ rays. Linear dose-response curves were obtained for both dose ranges. Presence of cysteamine during irradiation caused a decrease in the extent of DNA strand breaks. The kinetics of the DNA standard-break rejoining process appeared to be biphasic over the dose range of 2-20 Gy when plotted on a linear vs linear axis (percentage of damage as a function of time). No difference in the level of DNA strand breaks and the rate of repair of these breaks was observed between leukocytes from three ataxia telangiectasia patients and those from normal donors
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[en] The study of pulmonary clearance mechanisms has acquired particular importance owing to the growing pollution of the environment and to the increasing incidence and seriousness of cases of pneumoconiosis. Such research is particularly important in radiopathology because of the frequent occurrence of respiratory radioactive contamination. The authors' aim is to tackle this problem and in particular to study long-term clearance mechanisms. Before starting this work, however, they propose to determine the contamination parameters as accurately as possible. For this purpose they plan to study respiratory function in normal subjects by administering labelled aerosols with well-defined physico-chemical characteristics; the first stage of the investigation is then to observe the kinetics of fixation and clearance in the short term. They describe the installations used for this voluntary contamination which must provide a means of producing the aerosols and administering them in controlled amounts and must also ensure efficient protection of the operators against irradiation arid contamination. The choice of the aerosols is also discussed: this is governed mainly by the nature of the vectors, the particle size and the physical characteristics of the tracers. Finally, the authors outline the detection and measuring techniques which they are using to study contamination kinetics, evaluate contamination burdens and follow the short-term clearance. These data constitute a preliminary basis for the study of long-term clearance. (author)
[fr]
L'étude des mécanismes d’épuration pulmonaire est portée au fait de l'actualité, en raison, d'une part, de l'accroissement de la pollution de l'environnement et, d’autre part, de l’augmentation et de la gravité des pneumoconioses. Cette étude est particulièrement importante en radiopathologie du fait de la fréquence des radiocontaminations respiratoires. Les auteurs se proposent d’aborder ce problème et d’étudier plus précisément les mécanismes d’épuration a'long terme. Toutefois, avant d’entreprendre ce travail, ils entendent contrôler aussi parfaitement que possible les paramètres de contamination. Aussi se proposent-ils d’administrer â des sujets normaux sur le plan de la fonction respiratoire des aérosols marqués de caractéristiques physico-chimiques bien définies et d'en suivre dans un premier temps la cinétique de fixation et d’épuration a court terme. Ils décrivent les installations utilisées pour effectuer ces contaminations volontaires, installations qui doivent assurer la production d'aérosols et leur administration avec un rendement contrôlé et qui doivent en outre assurer une protection efficace contre l'irradiation et la contamination des opérateurs. Ils discutent le choix des aérosols administrés, ce choix portant notamment sur la nature des vecteurs, la taille des particules et les caractères physiques des traceurs. Ils indiquent enfin les techniques de détection et de mesures qu’ils utilisent pour étudier la cinétique de contamination, pour évaluer les charges de contamination et pour suivre l'épuration á court terme. Ces données constituent un travail préliminaire £ l'étude des épurations a long terme. (author)Source
International Atomic Energy Agency, Vienna (Austria); 924 p; Feb 1971; p. 857-869; Symposium on Dynamics Studies with Radioisotopes in Clinical Medicine and Research; Rotterdam (Netherlands); 31 Aug - 4 Sep 1970; IAEA-SM--136/112; ISSN 0074-1884; ; 20 refs., 1 tab., 5 figs.
; 20 refs., 1 tab., 5 figs.
[en] Short communication
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No abstract available
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[en] Total-body irradiation (TBI) induces an increase in levels of granulocytes and cortisol in blood. To explore the underlying mechanisms, we studied 26 patients who had TBI prior to bone marrow transplantation. Our findings suggest that only a high dose of TBI (10 Gy) was capable of activating the hypothalamopituitary area since corticotropin-releasing factor and blood adrenocorticotropic hormone levels increased at the end of the TBI. There was a concomitant increase in the levels of interleukin 6 and tumor necrosis factor in blood, suggesting that these cytokines might activate the hypothalamo-pituitary adrenal axis. Interleukin 1 was not detected. Since vascular injury is a common after radiation treatment, it is possible that interleukin 6 was secreted by endothelial cells. The exact mechanisms of the production of cyctokines induced by ionizing radiation remain to be determined. 25 refs., 1 fig
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[en] The authors show that in parallel to chromatin DNA cleavage, ribosomal RNA is lost in γ-ray-mediated apoptotic human lymphocytes, and demonstrate that 28S rRNA gene transcription is induced early (15 min) after irradiation, followed by selective disappearance in apoptotic cells only. The fact that newly synthesized rRNA turns over at the same rate in irradiated and untreated cell fractions, suggests the observed loss of 28S rRNA in the apoptotic cell fraction at the ribosome level is due to degradation occurring at a late stage of the apoptotic death process. Results suggest that, in addition to first-stage apoptosis-associated rDNA gene activation, cellular self-destruction at late stages is associated with processes occurring simultaneously at the ribosome level involving an endogenous RNase-like activity, and at the chromatin level involving DNA-nuclease activity. (author)
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