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Jung Ho Youm 4 Articles
Mercuric Chloride Induces Apoptosis in MDCK Cells.
Ju Hyoung Lee, Jung Ho Youm, Keun Sang Kwon
J Prev Med Public Health. 2006;39(3):199-204.
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AbstractAbstract PDF
OBJECTIVES
Mercury is a hazardous organ-specific environmental contaminant. It exists in a wide variety of physical and chemical states, each of which has unique characteristics for the target organ specificity. Exposure to mercury vapor and to organic mercury compounds specifically affects the CNS, while the kidney is the target organ for inorganic Hg compounds. METHODS: In this study, mercury chloride (HgCl2) was studied in a renal derived cell system, i.e., the tubular epithelial Madin-Darby canine kidney (MDCK) cell line, which has specific sensitivity to the toxic effect of mercury. MDCK cells were cultured for 6-24 hr in vitro in various concentrations (0.1-100 M) of HgCl2, and the markers of apoptosis or cell death were assayed, including DNA fragmentation, caspase-3 activity andwestern blotting of cytochrome c. The influence of the metal on cell proliferation and viability were evaluated by the conventional MTT test. RESULTS: The cell viability was decreased in a time and concentration dependent fashion: decreases were noted at 6, 12 and 24 hr after HgCl2 exposure. The increases of DNA fragmentation were also observed in the concentrations from 0.1 to 10 M of HgCl2 at 6 hr after exposure. However, we could not observe DNA fragmentation in the concentrations more than 25 M because the cells rapidly proceeded to necrotic cell death. The activation of caspase-3 was also observed at 6 hr exposure in the HgCl2 concentrations from 0.1 to 10 M. The release of cytochrome c from the mitocho-ndria into the cytosol, which is an initiator of the activation of the caspase cascade, was also observed in the HgCl2-treated MDCK cells. CONCLUSIONS: These results suggest that the activation of caspase-3 was involved in HgCl2-induced apoptosis. The release of cytochrome c from the mitochondria into the cytosol was also observed in the HgCl2-treated MDCK cells. These findings indicate that in MDCK cells, HgCl2 is a potent inducer of apoptosis via cytochrome c release from the mitochondria.
Summary
Effects of Mercury Chloride on Nitric Oxide Syntheses in Mouse Peritoneal Macrophage and EMT-6 Cell.
Keun Sang Kwon, Dai Ha Koh, No Suk Ki, Jung Ho Youm
Korean J Prev Med. 1997;30(2):369-380.
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AbstractAbstract PDF
The effects of treatment with mercury chloride on the nitrite and nitrate syntheses were observed in peritoneal macrophages from Balb/c mice and EMT-6 cells in vitro. The cells were cultured in Dulbecco's modified Eagle's medium(DMEM) with cytokines. Amounts of nitrite and nitrate in the culture media after 24 and 36 hours of culture were about 2-fold, and 3-fold of those measured after 12 hours respectively. There were very close associations between the amounts of nitrite and nitrate measured in the culture media according to culture time. The survival rate of peritoneal macrophages was significantly decreased by mercury chloride added into the media in dose-dependent manner, however the survivals of EMT-6 cells were not influenced by mercury chloride concentration in media. Nitrite and nitrate syntheses were dose-dependently decreased by mercury chloride added in culture media. ATP synthesis also decreased in EMT-6 cells by mercury chloride. These results reported here suggest that the disorder of cell mediated immunity by mercurials could be related to the inhibition of nitric oxide synthesis which seems to be caused by the inhibition of ATP synthesis.
Summary
NO2- and ATP synthesis in the EMT-6 cell stimulated by mercury chloride.
Gyung Jae Oh, Dai Ha Koh, Jung Ho Youm
Korean J Prev Med. 1996;29(3):495-506.
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AbstractAbstract PDF
Effect of Mercury chloride on the synthesis of NO2- and ATP were observed in EMT-6 cells which were culture with cytokines(IL-1alpha and IFN-gamma) and various concentrations of mercury chloride from 0.05 to 0.08 M. Viability of EMT-6 cells were observed above 90% in almost groups. There were not significant differences in the viability between mercury supplemented groups and control group. It suggests viability of EMT-6 cells were not influenced by these concentrations of mercury chloride. Results of the synthesis of nitrite showed significant time and group effect. There is a significant interaction effect between concentration of mercury chloride and culture time. The effect of various concentration of mercury chloride is not the same for all levels of culture time. There were significant differences in the synthesis of nitrite between mercury chloride supplemented groups and control group, and the synthesis of nitrite in EMT-6 cell by the supplement of mercury chloride was significantly decreased in a dose-dependent manner. Results of the synthesis of ATP showed a significant group effect, and the time main effect and the Group x Time interaction were also significant. There were significant differences in the synthesis of ATP between mercury chloride supplemented groups and control group, and the synthesis of ATP in EMT-6 cell by the supplement of mercury chloride was significantly decreased in a dose-dependent manner. These results suggest that the disorder of cell mediated immunity by mercury chloride could be related to the inhibition of nitric oxide synthesis which will be caused by the decreased synthesis of ATP.
Summary
Effect of Mercury Chloride on Humoral and Cell-mediated Immune Responses in Mice.
Jung Ho Youm
Korean J Prev Med. 1995;28(1):27-42.
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AbstractAbstract PDF
The in vivo and in vitro humoral and cell-mediated immune responses of lymphocytes of BALB/c mouse exposed to mercury chloride(HgC12) were investigated. In vitro exposure of the splenocytes to mercury chloride produced overt cytotoxicity in 3 hours period. The IC50(the concentration required to inhibit a splenocyte viability by 50%) for mercury chloride was >0.1mM for cytotoxicity. In vivo mercury chloride exposed mice were significantly depressed delayed type hypersensitivity(DTH) response to sheep red blood cells(SRBC) in a dose-dependent manner compared with control group. Mercury chloride inhibited the proliferative responses of splenocytes to lipopolysaccharide. pokeweed mitogen, concanavalin A and phytohemagglutinin in a dose-dependent manner. Hemagglutinin response to SRBC in mercury chloride exposed mice was significantly depressed in a dose-dependent manner compared with control group. After 7 weeks of mercury chloride exposure in vivo. mercury chloride induced an increase of nonspecific serum IgG1 and IgE levels in BALB/c mice.
Summary

JPMPH : Journal of Preventive Medicine and Public Health