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Chen, G., Upham, B. L., Sun, W., Chang, C. C., Rothwell, E. J., Chen, K. M., et al. (2000). Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells. Environ Health Perspect, 108(10), 967–972.
Abstract: Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.
Keywords: Cell Differentiation/*physiology; Cell Division; *Cell Transformation, Neoplastic; Electromagnetic Fields/*adverse effects; *Friend murine leukemia virus; Humans; Leukemia, Erythroblastic, Acute/*pathology; Telomerase/metabolism; Tumor Cells, Cultured
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Chen, H., Liu, R., Liu, J., & Tang, J. (2012). Growth inhibition of malignant melanoma by intermediate frequency alternating electric fields, and the underlying mechanisms. J Int Med Res, 40(1), 85–94.
Abstract: OBJECTIVE: This study investigated the antitumour effects of intermediate frequency alternating electric fields (IF-AEF) in a murine melanoma cell line (B16F10) and a mouse tumour model. METHODS: IF-AEF was applied at 100 kHz. Proliferation of B16F10 cells in vitro was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. IF-AEF was applied in vivo to mice bearing B16F10 tumours. Terminal deoxy nucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay for apoptosis, and immunohistochemical detection of CD34 and vascular endothelial growth factor (VEGF), were performed. RESULTS: IF-AEF inhibited the proliferation of B16F10 cells in an electrical intensity and time-dependent manner. Treatment with IF-AEF for 7 days significantly inhibited the growth of tumours compared with untreated controls. IF-AEF induced apoptosis in vivo and reduced CD34-positive cell numbers; CD34 is a special marker of microvessel density. CONCLUSION: IF-AEF reduced microvessel density related to tumour growth and may serve as a therapeutic strategy for cancer treatment.
Keywords: Animals; Antigens, CD34/metabolism; Apoptosis; Cell Proliferation; *Electricity; Immunohistochemistry; In Situ Nick-End Labeling; Kaplan-Meier Estimate; Melanoma/*pathology; Melanoma, Experimental/pathology; Mice; Mice, Inbred C57BL; Skin Neoplasms/*pathology; Vascular Endothelial Growth Factor A/metabolism
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Chen, Y., Hong, L., Zeng, Y., Shen, Y., & Zeng, Q. (2014). Power frequency magnetic fields induced reactive oxygen species-related autophagy in mouse embryonic fibroblasts. The International Journal of Biochemistry & Cell Biology, 57, 108–114.
Keywords: power frequency magnetic fields; reactive oxygen species
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Chikina, M. D., & Troyanskaya, O. G. (2012). An effective statistical evaluation of ChIPseq dataset similarity. Bioinformatics, 28(5), 607–613.
Abstract: MOTIVATION: ChIPseq is rapidly becoming a common technique for investigating protein-DNA interactions. However, results from individual experiments provide a limited understanding of chromatin structure, as various chromatin factors cooperate in complex ways to orchestrate transcription. In order to quantify chromtain interactions, it is thus necessary to devise a robust similarity metric applicable to ChIPseq data. Unfortunately, moving past simple overlap calculations to give statistically rigorous comparisons of ChIPseq datasets often involves arbitrary choices of distance metrics, with significance being estimated by computationally intensive permutation tests whose statistical power may be sensitive to non-biological experimental and post-processing variation. RESULTS: We show that it is in fact possible to compare ChIPseq datasets through the efficient computation of exact P-values for proximity. Our method is insensitive to non-biological variation in datasets such as peak width, and can rigorously model peak location biases by evaluating similarity conditioned on a restricted set of genomic regions (such as mappable genome or promoter regions). Applying our method to the well-studied dataset of Chen et al. (2008), we elucidate novel interactions which conform well with our biological understanding. By comparing ChIPseq data in an asymmetric way, we are able to observe clear interaction differences between cofactors such as p300 and factors that bind DNA directly. AVAILABILITY: Source code is available for download at http://sonorus.princeton.edu/IntervalStats/IntervalStats.tar.gz. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Keywords: *Algorithms; *Chromatin Immunoprecipitation; Genomics/*methods; Programming Languages; *Sequence Analysis, DNA; Transcription, Genetic
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Chiu, R. S., & Stuchly, M. A. (2005). Electric fields in bone marrow substructures at power-line frequencies. IEEE Trans Biomed Eng, 52(6), 1103–1109.
Abstract: Bone marrow is known to be responsible for leukemia. In order to study the hypothesis relating power-line frequencies electromagnetic fields and childhood leukemia from a subcellular perspective, two models of bone marrow substructures exposed to electric field are computed numerically. A set of cancellous bone data obtained from computed tomography scan is computed using both the finite element method (FEM) and scalar potential finite difference method. A maximum electric field enhancement of 50% is observed. Another model of bone marrow stroma cells is implemented only in FEM using thin film approximation. The transmembrane potential (TMP) change across the gap junctions is found to range from several to over 200 microV. The two results suggest that imperceptible contact currents can produce biologically significant TMP change at least in a limited number of bone marrow stroma cells.
Keywords: Animals; Bone Marrow Cells/*physiology/*radiation effects; Computer Simulation; Dose-Response Relationship, Radiation; Electric Conductivity; *Electricity; *Electromagnetic Fields; Hematopoietic Stem Cells/*physiology/*radiation effects; Humans; Membrane Potentials/*physiology/radiation effects; *Models, Biological; Radiation Dosage; Stromal Cells/physiology/radiation effects
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