Establishing an animal model to study the effects of sine wave electromagnetic fields on chondrosarcoma tumor growth and an investigating of the use of ion-pair HPLC analysis of nucleotides in chondrosarcoma tumor

During the past two decades, significant findings on the physiological consequences of exposure to electromagnetic field (EMF) have been coming from current research in various areas: cell function, epidemiology, bone healing and whole animal studies. Electromagnetic fields have both beneficial and harmful effects to humans. Pulsed electromagnetic fields (PEMFs) have been used clinically in the stimulation of the healing of fracture non-unions, when repeated surgical failures to heal patients with chronically ununited broken bone have occurred. On other hand, epidemiological studies have shown an increased risk of cancer among children who live close to power lines and among men whose jobs exposed them to unusually high levels of EMFs. In the present study, the effects of 15 Hz, 5 Gauss sine wave electromagnetic fields on Swarm chondrosarcoma tumor growth were examined. Several factors were established for an animal model to study the effects of sine wave EMF on the tumor growth. We determined the suitable amount of tumor for tumor implantation, optimal exposure time and the exposure dose for the experimental conditions. Two stages of tumor growth were defined: the early stage from Day 1 to Day 7, and the late stage after Day 8 post-implantation of the tumor. Our data indicated that sine wave EMF stimulates both stages of tumor growth but has a more effective stimulation on the early stage of tumor growth. In a second study, we investigated nucleotides of chondrosarcoma tissue and cell extract by using ion-pairing HPLC and studied the effects of hydroxyurea on the chondrosarcoma cell growth. When the ribonucleotide reductase inhibitor, hydroxyurea, is added to the chondrosarcoma cell culture, the dADP pool is reduced to 83% after 10 minutes of the treatment of 3 mM hydroxyurea, to 72% after 20 minutes and to 43% after 30 minutes hydroxyurea treatment. Tissue and cell extract contain many components and many peaks are present in the chromatogram. In order to make the analysis of deoxynucleotides easily, we selectively destroyed ribonucleotides by treating the cell and tissue extracts with periodate-amine. The results showed a complete destruction of ribonucleotides in the mixture of nucleotide standards. However, a significant loss of components was found in the tissue and cell extracts. These results suggested that the treatment of periodate oxidation is not a suitable method in measuring deoxynucleotides in the chondrosarcoma tissue and cell extracts