Simulated biological materials for electromagnetic radiation absorption studies

For the study of electromagnetic dosimetry and hyperthermia, it is necessary to simulate human biological materials. This can be done by chemical mixtures that are described in this paper. Formulas are presented for simulating bone, lung, brain, and muscle tissue in the frequency range of 100 MHz to 1 GHz. By using these preparations a realistic equivalent to the human body can be constructed.     

Postmortem changes of the dielectric properties of bovine brain tissues at low radiofrequencies

The dielectric properties of the bovine brain grey and white matter in the frequency range from 20 kHz to 100 MHz were measured at different times following animal death. Changes in the dielectric parameters versus time are interpreted in terms of the reduction of the cell volume fraction that results from either cell disintegration or cell size reduction. Good agreement between the computer fitted parameters and the values calculated from the Maxwell-Wagner model of the static dielectric constants was found. At frequencies above 1 MHz the changes of the dielectric properties are less pronounced, confirming earlier observations made by other investigators for different species.     

Zinc depletion suppresses tumor growth in mice

The hypothesis that in tumor-bearing animals an increase of host hepatic zinc metallothionein (Zn-MT) causes a restriction of zinc in the tumor tissue was studied. Three types of tumors were induced in laboratory mice by cell transplant. Tumor growth appears to be inhibited under zinc-deficient conditions, even in cases where zinc deficiency was started after tumor cell transplant. The survival times of tumor-bearing mice were prolonged by administration of cadmium chloride, which induces the synthesis of a combined zinc-cadmium metallothionein derivative in the host liver, but not in the tumor tissue, leading to an increase of hepatic zinc in the treated animals. The uptake of⁶⁵Zn by the liver of Cd-treated, tumor bearing mice was significantly higher than that of controls whereas uptake of⁶⁵Zn by tumor cells was significantly higher in controls than in the treated animals. These results suggest that restriction of zinc intake suppresses tumor growth.