Early and late effects on the normal dog brain of permanent interstitial iridium-192 irradiation.
Détails
ID Serval
serval:BIB_D6DBE0557640
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Early and late effects on the normal dog brain of permanent interstitial iridium-192 irradiation.
Périodique
Acta Neuropathologica
ISSN
0001-6322[print], 0001-6322[linking]
Statut éditorial
Publié
Date de publication
1986
Volume
70
Numéro
2
Pages
91-102
Langue
anglais
Résumé
To investigate the effects of a permanent interstitial source of gamma-irradiation on normal brain tissue, single iridium-192 (Ir-192) wires (1.05 mCi) were stereotactically implanted into the left centrum semiovale of adult dogs (survival times, 25, 46, 74, 230 and 362 days). Within 25 days, a coagulation necrosis developed in the immediate vicinity of the radioactive source. In later stages, the necrosis increased in size and became progressively mineralized. Staining for extravascular immunoreactive serum proteins revealed the presence of a chronic perifocal vasogenic edema, which extended into the white matter of the entire ipsilateral hemisphere. This edema persisted through all stages and showed a significant decrease only in the animal with a 1-year survival. A reactive gliosis with formation of a dense network of glial fibrillary acidic protein-positive astrocytes developed around the central necrosis in the adjacent white matter and, at later stages, in the contralateral hemisphere. Demyelination was restricted to the ipsilateral centrum semiovale without affecting the internal capsule or the contralateral hemisphere. It was present as early as 25 days and showed no tendency to increase at later stages. Analysis of the sequential morphological changes following Ir-192 implantation suggests that the central coagulation necrosis represents a direct radiation effect, the sharp focal delineation of which can be explained by the physical characteristics of the radiation source, i.e., rapid fall-off of the dose at short distances. Due to the continuous emission of radiation energy, there is a perifocal zone with overlapping of progressive radiation damage and tissue organization. This focus becomes the source of a chronic vasogenic edema, which in turn is most likely to be responsible for the partial demyelination of the adjacent centrum semiovale. The widespread reactive gliosis observed at all stages may also, in part, be a consequence of chronic vasogenic edema, but its distribution suggests that direct radiation effects may also be involved.
Mots-clé
Animals, Brain/pathology, Brain/radiation effects, Dogs, Iridium/adverse effects, Radiation Injuries, Experimental/pathology, Radioisotopes/adverse effects
Pubmed
Création de la notice
21/10/2010 8:50
Dernière modification de la notice
20/08/2019 16:56