Radiation therapy of rat brain tumor using misonidazole as hypoxic cell sensitizer

The additive effect of alpha-difluoromethylornithine (DFMO) and radiation therapy on a rat glioma model

The effects of alpha-difluoromethylornithine (DFMO), radiation and the therapy of their combination were investigated in rats bearing G-XII glioma. DFMO treatment as well as radiation therapy prolonged the survival period when compared to the results in non-treated control rats. The combination therapy showed a greater effect on the survival rate than the single therapies, the effect being additive. The concentration of putrescine, spermidine, and N1-acetylspermidine in tumor tissue was lowered by DFMO, while that of spermine was slightly elevated. Radiation decreased the concentration of all the polyamines, putrescine, spermidine, spermine and N1-acetylspermidine. The concomitant treatment with DFMO and radiation further decreased the concentrations of putrescine and N1-acetylspermidine in tumor tissues. The survival period of glioma-bearing rats is inversely correlated with the tissue levels of putrescine plus N1-acetylspermidine.

Three-dimensional observations on microvascular growth in rat glioma using a vascular casting method

The microvascular growth of ethylnitrosourea-induced rat glioma was observed using vascular casting and scanning electron microscopy (SEM). Light microscopy showed central necrosis and marginal invasive tumor cell growth with increased vascularity, and suggested that adopted pre-existing circulation was dominant in the inoculated brain tumors. In SEM, numerous buds or nodular protrusions and a few large and tortuous vessels along the tumor margin were seen at the early stage. In the intermediate stage, microaneurysms, buds with septum formation and anastomotic arches appeared, and these tumor vessels became more tortuous and larger, and extended as the tumor grew. Several "potato-shaped" huge vessels and linear nodular large vessels also appeared. In the late stage, glomeruli appeared and potato-shaped huge vessels increased in number. The neovascularization and microvascular growth of the tumors was characterized by three patterns: (a) growth of the parent vessels forming buds, (b) vascular growth in a meshwork formation producing glomeruli, and (c) vascular enlargement without a definite pattern creating potato-shaped huge vessels. The tumor vessels gradually lost their natural three-dimensional structure.