Long-term effects of 60-Hz electric vs. magnetic fields on IL-1 and IL-2 activity in sheep.

This study was designed to assess the effect of exposure to long-term extremely low-frequency electric and magnetic fields (ELF-EMF) from a 500 kV transmission line on IL-1 and IL-2 activity in sheep. The primary hypothesis was that the reduction in IL-1 activity observed in our two previous short-term studies (10 months) was due to EMF exposure from this transmission line. To repeat and expand these studies and to characterize the components of EMF responsible for the previously observed reduction in IL-1 activity, the current experiment examined not only the effect of exposure to electric and magnetic fields, but also the magnetic field component alone. In the current study, IL-2 was examined to characterize the effects of EMF exposure on an indicator of T cell responses. 45 Suffolk ewe lambs were randomized into three groups of 15 animals each. One group of animals was placed in the EMF pen, located directly beneath the transmission line. A second group was placed in the shielded MF (magnetic field only) pen, also directly beneath the transmission line. The third group of animals was placed in the control pen located several hundred meters away from the transmission line. During the 27 month exposure period, blood samples were taken from all animals monthly. When the data were analyzed collectively over time, no significant differences between the groups were found for IL-1 or IL-2 activity. In previous studies ewe lambs of 8-10 weeks of age were used as the study animals and significant differences in IL-1 activity were observed after exposure of these animals to EMF at mean magnetic fields of 3.5-3.8 microT (35-38 mG) and mean electric fields of 5.2-5.8 kV/m. At the start of the current study EMF levels were reduced as compared to previous studies. One interpretation of the current data is that magnetic field strength and age of the animals may be important variables in determining whether EMF exposure will affect IL-1 activity.

Quantification of DNA binding to cell-surfaces by flow cytometry.

DNA binding to cell-surfaces has been documented in several studies. The interaction of DNA with cells has been shown to have therapeutic potential as a non-viral form of gene delivery and DNA vaccination. Recently, bacterial DNA binding and internalization has been demonstrated in some cells to trigger secretion of cytokines and cell activation. Previous studies to quantify DNA binding to cells have used radiolabeled DNA. Here we report a non-radioactive assay for quantification of cell-surface DNA binding based on the isoparametric analysis of flow cytometric data as described by Chatelier et al., Embo J., 5 (1986) 1181. This assay has the advantage over previously used procedures in not employing radioactive material and being able to discriminate viable from non-viable cells that bind DNA. With the importance of understanding the interaction of DNA with cells, this assay may have application for the identification and characterization of reagents designed to either enhance or inhibit DNA binding to cells.

Intranuclear degradation of the transformation-inducing protein encoded by avian MC29 virus.

The nuclear protein, p110, encoded by the avian MC29 virus degrades with a half-life of 30 to 40 min in virus-transformed cells. Inhibitors of lysosomal proteolysis had no effect on this degradation. When inhibitors of RNA or protein synthesis were added immediately after pulse-labeling the p110 with [35S]methionine, degradation was impeded. Treatment of cells with cycloheximide prior to, and after, the pulse extended the half-life of p110 further than post-treatment alone, and addition of both actinomycin D and cycloheximide to cells pretreated with cycloheximide extended the half-life even further. In cells depleted of cellular ATP using a glucose-deficient medium containing oligomycin, degradation of p110 was only partially inhibited, indicating no direct involvement of ATP in degradation. Isolation of nuclei or nuclear matrices containing labeled p110, with subsequent incubation, resulted in minimal loss of p110 during several hours. These results suggest that p110 is degraded by a protease which is itself labile and freely diffusible from the nucleus, and, in addition, degradation may involve interaction of p110 with newly synthesized RNA.