Increased Radioresistance to Lethal Doses of Gamma Rays in Mice and Rats after Exposure to Microwave Radiation Emitted by a GSM Mobile Phone Simulator

The aim of this study was to investigate the effect of pre-irradiation with microwaves on the induction of radioadaptive response. In the 1(st) phase of the study, 110 male mice were divided into 8 groups. The animals in these groups were exposed/sham-exposed to microwave, low dose rate gamma or both for 5 days. On day six, the animals were exposed to a lethal dose (LD). In the 2(nd) phase, 30 male rats were divided into 2 groups of 15 animals. The 1(st) group received microwave exposure. The 2(nd) group (controls) received the same LD but there was no treatment before the LD. On day 5, all animals were whole-body irradiated with the LD. Statistically significant differences between the survival rate of the mice only exposed to lethal dose of gamma radiation before irradiation with a lethal dose of gamma radiation with those of the animals pre-exposed to either microwave (p=0.02), low dose rate gamma (p=0.001) or both of these physical adapting doses (p=0.003) were observed. Likewise, a statistically significant difference between survival rates of the rats in control and test groups was observed. Altogether, these experiments showed that exposure to microwave radiation may induce a significant survival adaptive response.

Microencapsulation of theophylline using ethylcellulose: in vitro drug release and kinetic modelling

This study details the process of coating theophylline with ethylcellulose using the coacervation technique of microencapsulation. Microencapsulation of theophylline not only renders it sustained-release, but also decreases its gastric irritation and masks the bitter taste (Lin and Yang 1987). The non-solvent addition method was chosen through a literature survey to ascertain various phases of the coacervate (Robinson 1989, Nixon and Wong 1990). A three-phase diagram was used to determine the optimum quantity of each component required. Steps were then carried out to optimize the production. Drug release rates of the prepared microcapsules were determined over 12-h cycles using the U.S.P. dissolution apparatus and the results obtained were compared with those of Knoll's (Germany) sustained-release theophylline capsules. Significant control over the rate of drug released from the developed dosage form was achieved during the experiment time (12 h). It is concluded that the method employed in this study could be effectively used in the preparation of sustained-release theophylline microcapsules capable of releasing their drug content for an extended period of time. Kinetic studies suggested that both the prepared microcapsules and Knoll's product followed Higuchi's model for drug release. Particle size and release data analysis from five consecutive batches prepared in the laboratory indicated suitable reproducibility of the coacervation process.