Fisher 344 (pregnant female) rats were exposed to an 835 MHz TDMA signal in a head first manner for 2 hours in a carrousel irradiator at 0.16, 1.6 W/kg (brain average SAR). Fetal rat pup brains were analyzed 24 hours after the last exposure session, and ODC enzyme activity levels did not change. The DNA repair enzyme Acyl-Guanine Transferase (AGT), however, was observed to decrease in initial studies, but was then observed to increase in subsequent studies. The effects were attributed to experimental variation and no effects were ultimately reported. In subsequent in vivo studies, Fisher 344 (pregnant female) rats were exposed for 2 hours to 1616 MHz IRIDIUM signals in a tail first manner in a carrousel irradiator at 0.16, 1.6, and 5 W/kg (brain average SAR). In the fetal rat pup cerebrum, ODC enzyme activity decreased to about the same extent at all SAR levels (56-59% of sham levels) with no change in putricine, spermine, or spermidine levels. In the cerebellum, ODC levels decreased with respect to sham levels in the reverse of a dose response pattern (60% @ 0.16 W/kg, 83% @ 1.6 W/kg, 89% @ 5 W/kg) while putricine levels increased with increasing dose (150% @ 0.16 W/kg, 145% @ 1.6 W/kg, 83% @ 5 W/kg). Although these data did not correlate with previous reports of ODC activity and putricine changes in Bioelectromagnetics literature, the authors speculated that this result may stem from a more complex mechinism of RF interaction in vivo. However replication attempts by Anderson et al (2005) could not confirm the findings at 1.6 GHz (IRIDIUM).