Modulation of normal tissue responses to radiation

Modification of doxorubicin-induced cardiotoxicity: effect of essential fatty acids and ICRF-187 (dexrazoxane)

The capacity of an oil, containing gamma-linolenic acid (GLA), to reduce the severity of doxorubicin-induced cardiotoxicity has been investigated in a rat model. Groups of 12-week-old, male, Sprague-Dawley rats were injected intravenously (i.v.) with single doses (3 mg/kg body weight) of doxorubicin (DOX). Daily for 1 week prior to DOX administration and for up to 20 weeks afterwards groups of rats received either an oil containing both GLA and linoleic acid (So-1100, Scotia Pharmaceuticals), at two dose levels, or an oil containing linoleic acid, but no GLA (So-1129) by oral gavage. Other groups of rats received water as a control. One of the groups of rats that received water also received i.v. ICRF-187 (60 mg/kg) 15 min prior to DOX. A group of animals acted as age-matched controls. The maximum reduction in body weight in the first 2 weeks after the administration of DOX. was used as a measure of acute toxicity. This was most severe in the group receiving a combination of DOX and ICRF-187 (5.6+/-0.43%). Animals receiving 2 ml of either So-1100 or So-1129 were the least affected ( approximately 2.5%). Measurements of cardiac volume output made at various intervals after DOX administration indicated a approximately 35% reduction in cardiac function in the control and So-1129 oil group after 20 weeks. The corresponding reduction in the groups receiving ICRF-187 and 2 ml of So-1100 was approximately 16%. The group receiving daily doses of 1 ml So-1100 showed an intermediate response. The death of an animal with signs of congestive cardiac failure occurred in 40% of the animals in the DOX only control (water) group. There were no deaths in the groups of rats receiving either ICRF-187 or pre- and post-administration of 2 ml of So-1100. It was concluded that an oil containing GLA (So-1100) has similar cardioprotective properties against DOX-induced cardiotoxicity as ICRF-187, but with less general toxicity in this rat model.

Radiation myelopathy: new perspective on an old problem

This article discusses recent advances in basic research that alter the view of the pathogenesis of radiation myelopathy and summarizes the available data from developmental neurobiology and preclinical studies on demyelinating diseases. These studies have produced interesting insights into oligodendrocyte development, intercellular signaling pathways, and myelination processes. Current findings suggest that administration of cytokines as platelet-derived growth factor and basic fibroblast growth factor could increase proliferation of oligodendrocyte progenitors, enhance their differentiation, up-regulate synthesis of myelin constituents, and promote myelin regeneration in the adult central nervous system (CNS). Other compounds might also be able to modulate the progression of pathogenic processes that lead to myelopathy. In addition, several possible biological prevention or treatment strategies, for example stimulation of endogenous cellular regeneration and glial cell transplantation, are discussed. Rationally designed animal experiments pursuing such strategies could further elucidate the pathogenesis of radiation-induced CNS damage.