Jeffrey D. Saffer

Short exposures to 60 Hz magnetic fields do not alter MYC expression in HL60 or daudi cells

Analysis of changes in gene expression induced by 60 Hz magnetic fields has been considered to support an association between exposure to magnetic fields and cancer risk. Several reports have indicated that these fields rapidly activate many genes in mammalian cells. However, previous studies in this area have not provided sufficient information to support the conclusions drawn. To clarify this controversial research, we have attempted to validate, under rigorously controlled conditions, key experiments on induction of gene expression by magnetic fields. An extensive series of experiments, incorporating critical improvements in experimental design, most notably blind exposures and internal standards, was performed with human HL60 and Daudi cells. Exposure conditions covered a range of flux densities (5.7 microT to 10 mT) and times (20-60 min). No alteration in the human MYC gene, commonly referred to as c-myc, or beta-actin steady-state mRNA levels was observed. The lack of an effect was not attributable to exposure geometry, timing of RNA preparation, or serum lot and concentration. To eliminate any remaining variables, exact replication was performed in one of the laboratories previously reporting gene expression effects; again, no evidence for altered MYC expression was found. Finally, differential display PCR indicated that extremely low-frequency magnetic field-induced changes in gene expression were not prevalent.

Ultraviolet shadowing nucleic acids on nylon membranes

We describe a method for the direct visualization of nucleic acids on nylon membranes. Nylon is weakly fluorescent under short wave ultraviolet light allowing membrane-bound nucleic acids to be detected with a sensitivity of 10 ng. This procedure involves no staining or destaining of the gels prior to transfer, does not require duplicate sample lanes or blots, and does not interfere with transfer of the nucleic acid to the membrane or subsequent hybridization.

EVALUATING THE BIOLOGICAL ASPECTS OF IN VITRO STUDIES IN BIOELECTROMAGNETICS

Abstract In-vitro experiments are frequently used to examine the causal mechanisms for biological change induced by chemical and physical agents. In many studies, the hope is that in-vitro experiments will lead to knowledge of mechanisms that may occur in in-vivo systems, which in turn may or may not have implications for human health and development. Unfortunately, however, in-vitro studies defining the effects of electromagnetic field (EMF) exposures on biological systems have, in part, been characterized by intra- and inter-laboratory inconsistencies and by relatively small, rather than robust, effects. Debate about the significance of the reported observations has ensued, with the interdisciplinary nature of bioelectromagnetics being a major contributing factor in the difficulty of understanding the results. In-vitro studies in bioelectromagnetics require expertise in a variety of biological sciences as well as engineering and physical sciences. As a result, evaluating the results of these in-vitro studies is frequently difficult, especially for those lacking familiarity with the properties of dynamic biological systems, specific laboratory techniques or the appropriate biomedical literature. Hence the purpose of this paper is to provide a discussion of some of the sources of biological and technical variability in the context of classic biological studies as well as EMF-specific issues. Understanding the nature of experimental variability and the means to define that variability can provide a general framework allowing in-vitro EMF studies to be interpreted more easily and more correctly and permitting thoughtful consideration of apparently inconsistent results.

Localization of the gene for the trans-acting transcription factor Sp1 to the distal end of mouse chromosome 15.

The mouse chromosomal location for the gene (Sp1-1) encoding the trans-acting transcription factor Sp1 has been determined. Analysis of restriction fragment length polymorphisms in recombinant inbred, congenic, and interspecific backcross mice using human and mouse cDNA probes demonstrated that Sp1-1 is a single gene closely linked to the mammary tumor virus integration site-1 (Int-1) on the distal end of chromosome 15. Sp1 is a zinc finger protein, but Sp1-1 is not closely linked to any of the other zinc finger protein genes that have been mapped in mouse. Int-1 and other markers flanking the Sp1-1 locus are part of a conserved linkage group represented on human chromosome 12q.

DNA fingerprinting by arbitrarily primed PCR (RAPDs)

Microbial ecosystems are characterized by genetic and taxonomic diversity. Investigations of microbial diversity have gained benefits from the development of various typing techniques to distinguish strains more precisely [1, 10, 14, 19]. These techniques may be divided into two categories, those based on phenotypic and those based on genotypic characters. Typing techniques based on phenotype include isozyme electrophoresis, whole-cell protein profiling [17], sugar metabolism profiling, total fatty acids profiling [6], phage typing [7], and various immunoblotting techniques [10, 12]. Typing techniques based on genotype include DNA-DNA hybridization, restriction enzyme analysis, RFLP, ribotyping [1], plasmid profiling [4, 5] and DNA fingerprinting by Arbitrarily Primed PCR (APPCR) [23, 24], RAPDs (Random Amplified Polymorphic DNA) [29], or rep-PCR [20]. APPCR is the subject of this chapter.

Extremely Low Frequency Electromagnetic Fields and Cancer

Because of the exceedingly small energies associated with power frequency (50 or 60 Hz) electric and magnetic fields (EMF), the possibility that these fields might be linked to increased cancer incidence was not seriously considered in the scientific community before the last decade. A series of epidemiologic studies (1–5), however, has led to considerable current debate as to whether exposure to extremely low frequency (ELF) electric and magnetic fields can be contributing factors to cancer risk in humans.