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Description: Iodoacetamide has been shown by others to be a radiation sensitizer for bacteria and for certain mammalian cells tested in vitro. This work describes an examination of the effectiveness of iodoacetamide used in vivo. Survival of ascites tumor cells maintained in the peritoneal cavity of mice was used as an indicator of sensitization. Survival was assessed using TD{sub 50} and total tumor cell population determination methods. A comparison of results obtained by these methods is made. The effects of oxygen tension and radiation dose rate upon results was examined. Iodoacetamide was found to be effective as a radiation sensitizer under all conditions although to a lesser degree than that reported by others for in vitro experiments with bacteria. Radioactive tracer studies indicate that iodoacetamide has rapid and total access to most if not all tissues of the body. This fact coupled with the observation of a sensitization in an in vivo system where the anoxia so prevalent in well developed tumors was present, suggests the possibility of clinical usefulness of iodoacetamide in cancer radiation therapy. Certain observations are reported on the effect of various cell and host treatment procedures upon cell population growth kinetics seen subsequent to inoculation of hosts with the cells. A hypothesis is presented which can account for the observations made by the author and also for those made by some others who report that large inocula, i.e., greater than 10 cells, are required to give rise to a lethal tumor in isologous hosts of the strain of tumor origin. The hypothesis may also account for what is known in the literature as the 'Hybrid Effect.'
Date: October 1, 1970
Creator: Richards, F. Robert & Kelly, Lola S.
Partner: UNT Libraries Government Documents Department