Effects of electromagnetic fields on signal transduction pathways leading to HL-60 cell differentiation.
Item
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Title
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Effects of electromagnetic fields on signal transduction pathways leading to HL-60 cell differentiation.
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Identifier
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AAI9959237
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identifier
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9959237
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Creator
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Tao, Qi.
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Contributor
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Adviser: Ann S. Henderson
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Cell | Biology, Molecular
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Abstract
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The purpose of this study was to examine the hypothesis that cancer-related changes could occur in cells exposed to extremely low frequency electromagnetic fields (elf-EM fields). The research was designed to provide a means of simply confirming or negating a connection between electromagnetic field exposure and cell responses. Several studies were carried out. The first study showed that low energy electromagnetic field exposure promotes cellular differentiation in HL-60 cells in a manner similar to treatment with a known tumor promoter, TPA. The results using microscopic analyses demonstrated that similar morphological changes appeared following either EM field exposure or TPA treatment. Result of studies that used flow cytometry analyses showed a significant increase in the number of phagocytic cells that was observed after HL-60 cells were exposed to 1 G and 2G EM field at 24 hours. There is a linear dose-response in HL-60 cells to low concentrations of TPA as low as 50--250 pg/ml. The relative effect of a 1G EM field on HL-60 cells at 24 hours is approximately equivalent to that of 250--500 pg/ml TPA. The data also showed that there was an additive effect when EM field exposure and TPA were used together at lower concentrations of TPA (50--500 pg/ml). The additive effect declined as the TPA concentration was increased, i.e., the effects were swamped out by TPA at concentration of 1 ng/ml and above. This study suggests that EM fields and TPA could share common transduction pathways.;The second part of the study was designed to determine if exposure to EM fields affects protein kinase C (PKC) membrane translocation. TPA can cause significant PKC-alpha translocation and total PKC-alpha is down-regulated. Cells exposed to 60 mG EM fields showed changes in PKC translocation, but the differences were not statistically significant. Cells exposed to 1 G EM field exposure showed a trend that was consistent with PKC translocation. However, at most time points, the increase was not significant. Total PKC-alpha is not down-regulated in long term-EM field exposure. This suggest that either PKC is unaffected by EM exposure or that the relative effect of an EM field is very low.;This study implies that both EM field exposure and TPA treatment share the ability to initiate a set of common consequences in cell differentiation and molecular signal transduction. PKC, however, responds to TPA treatment and EM field exposure differently. The insignificant changes of PKC translocation in cells exposed to EM field implies that alternative signaling pathways, i.e., cell surface membrane tyrosine kinase receptors may be involved.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
