Radiosensitization by nicotinamide in tumors and normal tissues: the importance of tissue oxygenation status
Nicotinamide induced radiosensitization of tumors has been suggested to be a consequence of a reduction in tumor hypoxia. We have investigated the possibility that nicotinamide may produce significant radiosensitization in a normal tissue in which the radiation response is also influenced by hypoxia. The normal tissue studied was testis and radiation damage was assessed by measuring survival of spermatogonial stem cells. The radiosensitizing action of nicotinamide in testis was compared to that observed in a C3H mammary carcinoma when assayed by both regrowth delay and local tumor control. Our results show that nicotinamide (1000 mg/kg; i.p.) enhanced radiation damage in both tissue types when the radiation was given up to at least 3 hr after drug injection. Enhancement ratios obtained when the drug and radiation were separated by a 1 hr time interval were between 1.1 to 1.2 for the testis and 1.0 to 1.5 for the tumor. The results suggest that nicotinamide will produce radiosensitization in testis, but the effect is small and less than that observed in tumors.
- Research Organization:
- Danish Cancer Society, Aarhus
- OSTI ID:
- 5901402
- Journal Information:
- Int. J. Radiat. Oncol., Biol. Phys.; (United States), Journal Name: Int. J. Radiat. Oncol., Biol. Phys.; (United States) Vol. 16:5; ISSN IOBPD
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMIDES
ANIMAL CELLS
ANIMALS
ANOXIA
AZINES
BODY
GAMETES
GERM CELLS
GONADS
HETEROCYCLIC COMPOUNDS
MALE GENITALS
MAMMALS
MICE
NICOTINAMIDE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRIDINES
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
RODENTS
SOMATIC CELLS
SPERMATOGONIA
STEM CELLS
TESTES
VERTEBRATES
VITAMIN B GROUP
VITAMINS