Radioprotective effects of serum thymic factor in mice.

Serum thymic factor (FTS) reduced mortality of mice after total-body irradiation with 7.56 Gy X rays. The radioprotective effect was achieved by daily repeated subcutaneous injections of 3-100 micrograms FTS, while doses higher than 300 micrograms/day/mouse were neither radioprotective nor toxic. Similarly, degeneration of the spleen was moderated by 3-100 micrograms FTS but not by 500 micrograms FTS in sublethally (3.78 Gy) irradiated mice. Histological examination showed that hematopoiesis was enhanced in the spleen by daily injections of 10 micrograms FTS. Spleen cells from the FTS-treated mice incorporated more [3H]thymidine in culture with or without concanavalin A. The treatment with FTS increased the production of colony-stimulating factor in the spleen as well as in peritoneal macrophage-like cells, and caused a significant increase in the number of granulocyte-macrophage colony-forming cells both in the spleen and in the femoral bone marrow. Furthermore, FTS prevented a decrease in circulating neutrophils in the sublethally irradiated mice. Prominent overshoot recovery of myelopoiesis, which occurred occasionally in sublethally irradiated mice, did not occur in the FTS-treated mice. The decrease in blood erythrocytes was also significantly reduced. These observations imply that this thymic hormone has potential as a radioprotector.

In vivo biological effects of stereotactic radiosurgery: a primate model.

Single-fraction, closed skull, small-volume irradiation (radiosurgery) of intact intracranial structures requires accurate knowledge of radiation tolerance. We have developed a baboon model to assess the in vivo destructive radiobiological effects of stereotactic radiosurgery. Three baboons received a single-fraction, 150-Gy lesion of the caudate nucleus, the thalamus, or the pons using the 8-mm diameter collimator of the gamma unit. Serial standard neurodiagnostic tests (neurological examination, computed tomographic scan, magnetic resonance imaging, stable xenon-enhanced computed tomographic scan of cerebral blood flow, somatosensory and brain stem evoked potentials, and myelin basic protein levels of cerebrospinal fluid) were compared with preoperative studies. Magnetic resonance imaging revealed the development of a lesion at the target site between 45 and 60 days after irradiation. Deterioration of the brain stem evoked potentials preceded imaging changes when the lesion encroached on auditory pathways. Myelin basic protein levels increased subsequent to imaging changes. Postmortem neuropathological examination confirmed a well-demarcated radionecrosis of the target volume. The baboon model appears to be an excellent method to study the in vivo biological effects of radiosurgery.

[Effect of gamma-irradiation on the enzyme activity of cerebrospinal fluid lymphocytes in dogs]. / Vliianie gamma-oblucheniia na fermentativnuiu aktivnost' limfotsitov likvora sobak.

Cytochemical activity of succinate dehydrogenase (SDG), L-glycerophosphate dehydrogenase (L-GPDG), lactate dehydrogenase (LDG), and glutamate dehydrogenase (GDG) increased immediately after total-body irradiation with a dose of 129 mC/kg. After 2 h, LDG activity only returned to the control level. Irradiation of the head with the same dose caused less pronounced changes. Changes caused by lethal irradiation (1290 mC/kg) were different: there was an increase after exposure of the abdomen and a decrease in the activity of SDG and L-GPDG after irradiation of the head.