Lack of promotion of 7,12-dimethylbenz[a]anthracene-initiated mouse skin carcinogenesis by 1.5 GHz electromagnetic near fields.

The effects of 1.5 GHz electromagnetic near fields of time division multiple access (TDMA) signal for the Personal Digital Cellular, Japanese cellular telephone standard (PDC) used for cellular phones, on mouse skin carcinogenesis initiated by 7,12-dimethylbenz[a]anthracene (DMBA) were examined. Ten-week-old ICR female mice were treated with a single application of DMBA on shaved dorsal skin by painting at a concentration of 100 microg/100 microl acetone per mouse. One week later, mice were divided into four groups, receiving electromagnetic near fields exposure (DMBA-EMF), sham-exposure (DMBA-Sham), 12-O-tetradecanoylphorbol-13-acetate (TPA, 4 microg /200 microl acetone/mouse), as a positive control (DMBA-TPA), and no-treatment (DMBA-Control). EMF near fields exposure conditions were as follows: skin local peak specific absorption rate (SAR) 2.0 W/kg, whole body average SAR 0.084 W/kg (ratio of peak to average SAR is 24), 90 min a day, 5 days a week, for 19 weeks. At week 20, animals were killed and skin tumors were analyzed histopathologically. The incidences of skin tumors in DMBA-EMF, DMBA-Sham, DMBA-TPA and DMBA-Control groups were 0/48 (0%), 0/48 (0%), 29/30 (96.6%) and 1/30 (3.3%), respectively. Histopathologically, papilloma and squamous cell carcinoma (SCC) were observed in the DMBA-TPA group and only papilloma observed in the DMBA-Control group. The incidences of squamous cell papillomas and squamous cell carcinomas in DMBA-TPA and DMBA-Control groups were 29/30 (96.6%) and 1/30 (3.3%), respectively, numbers of tumors per mouse (tumor multiplicity) being 18.8 +/- 13.4 and 0.1 +/- 0.5. These data clearly demonstrated that near fields exposure to 1.5 GHz EMF, used for cellular phones, does not exert any enhancing effect on skin tumorigenesis initiated by DMBA.

Single local injection of recombinant fibroblast growth factor-2 stimulates healing of segmental bone defects in rabbits.

The effects of a single local injection of recombinant human fibroblast growth factor-2 on the healing of segmental bone defects were evaluated in rabbits. One month after the external fixator originally designed for this experiment was installed in the tibia of the rabbit, a 3-mm bone defect was created by an osteotomy in the middle of the tibia and 0, 50, 100, 200, or 400 microg of fibroblast growth factor-2 in 100 microl of saline solution was injected into the defect. Injection of the growth factor increased the volume and mineral content of newly made bone at the defect in a dose-dependent manner with significant effects at concentrations of 100 microg or greater. These significant effects were observed at 5 weeks and later. One hundred micrograms of the growth factor increased the volume and mineral content of newly made bone by 95 and 36%, respectively, at 5 weeks. These results indicate that a single local injection of fibroblast growth factor-2 stimulates the healing of segmental defects. We speculate that such an injection could be clinically useful for the healing of fractures even when the fracture gap is rather large.