Researchers report a milestone in the use of targeted energy--such as heat delivered by ultrasound--to locally switch on and control the activity of gene therapy vectors. For example, gene therapy of this nature could be used to enhance the effectiveness of radiation therapy, say Eugene Gerner and Evan Hersh of the Arizona Cancer Center at the University of Arizona College of Medicine, Tucson. The gene vectors contain gene components or promoters constructed via DNA genetic engineering. The researchers found that the promoters activate and amplify the expression of the therapeutic gene when cells containing the gene are heated to a few degrees above normal body temperature. Sponsored by Varian Biosynergy Inc., Palo Alto, Calif., the research is aimed at developing new treatment techniques as well as finding new applications for existing medical devices.