Chemical modifiers of XXXX treatment.

@entity137 @entity8712 @entity5 @entity11256 @entity26 @entity8503 @entity2041 @entity1432 @entity519 @entity11997 @entity13682 @entity12184
Chemical modification is a concept in @entity5 therapy in which the state of @entity5 cells or normal tissues is modified such that a therapeutic gain can be achieved using conventional therapeutic modalities. @entity519 zones targeted as cells within them may be radiation resistant, poorly perfused by chemotherapeutic agents, and possibly drug resistant due to @entity519 -related gene amplification. Nitroimidazoles have gained particular attention as chemical modifiers because they can increase the radiation sensitivity of @entity519 cells, are cytotoxic to @entity519 cells, can increase sensitivity to chemotherapeutic agents, and are useful for imaging @entity519 cells. While both radiosensitization and chemosensitization require @entity519 , the mechanism of the enhancement of each of the modalities is different. The @entity13682 @entity519 sensitizers @entity11256 and @entity12184 , which are less toxic than the prototype @entity8712 (Miso), are in clinical trials, and dual function molecules that include a @entity519 sensitizer and alkylating function are being developed. The presence of both acutely and chronically @entity519 cells in animal @entity5 has been demonstrated by new imaging techniques. @entity26 delivery to @entity5 is being altered by the use of @entity11997 , and agents that alter hemoglobin affinity for @entity26 . Compounds that are selectively toxic to @entity519 cells are being developed. Nonhypoxic modifiers are also being investigated. @entity1432 modification, particularly the alteration of @entity2041 concentration, has complex effects on the cell's biochemistry, in addition to affecting the competition between @entity26 and @entity1432 groups for the restoration and fixation of radiation-induced radicals. @entity8503 is being studied as a means of reducing the normal tissue @entity137 of radiation and chemotherapy. Increased @entity1432 concentration may be a mechanism of cross-resistance between certain chemotherapeutic agents and radiation.
