• Journal of Plant Biology
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• v.12 no.3
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• pp.1-7
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• 1969

The lethal actions in Arabidopsis thaliana and Lemna polyrhiza brought about by certain inorganic form of Mn, Ba, Hg, Cu salts, and organic form of Na salts, were studied with aseptic artificial media. These metal ions at certain concentrations caused lethality of either Arabidopsis or Lemna when the media were without Ca ion. On the contrary, addition of Ca to the media protected the organisms from such lethality. It was postulated for the present from the proceeding evidence that Ca adsorbed and distributed along the sites between the plasma and cell membrane acts for suppressing permeation of toxic level of metal ions causing the lethality of these plants.

• Archives of Pharmacal Research
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• v.25 no.5
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• pp.652-654
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• 2002

Brine shrimp assay-guided fractionation and isolation of the EtOAc soluble fraction of Phryma leptostachya L. (Phrymacaceae) gave two active compounds, phrymarolin II (1) and ursolic acid (2), which were identified by physicochemical and spectroscopic methods. Compound 1 exhibited potent lethality with $LD_{50}$ value of 0.0013 $\mu\textrm{g}$/ml, whereas 2 showed moderate lethality with $LD_{50}$ value of 27.0 $\mu\textrm{g}$/ml against brine shrimp. The cytotoxic activities of 1 and 2 were also evaluated against one murine and five human cancer cell lines employing the sulforhodamin B (SRB) method. Compound 2 exhibited cytotoxic activity against L1210 and SK-MEL-2 cells with $ED_{50}$ values of 3.70 and 9.27 mg/ml, respectively, whereas 1 was devoid of any cytotoxic activity against all cancer cells tested.

• Advances in Traditional Medicine
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• v.9 no.2
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• pp.182-185
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• 2009

Amoora cucullata (Meliaceae), a mangrove plant, has folkloric reputation as a medicinal agent in Bangladesh. In this study, the n-hexane, ethyl acetate and methanolic extracts of the stem bark of this plant were subjected to microbiological investigation and brine shrimp lethality bioassay. In case of antimicrobial screening, the ethyl acetate and methanolic extracts appeared to be potent in terms of both zone of inhibition and spectrum of activity showing the average zones of inhibition 8 - 14 mm and 9 - 16 mm, respectively. In the brine shrimp lethality bioassay, the methanolic extract demonstrated highest cytotoxicity having $LC_{50}$ of $0.549{\mu}g/ml$, whereas the ethyl acetate and n-hexane extract showed $LC_{50}$ of 7.943 and $17.180{\mu}g/ml$, respectively.

• Toxicological Research
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• v.14 no.4
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• pp.557-562
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• 1998

Allyl alcohol is metabolized in the liver through two steps, first to reactive acrolein by alcohol dehydrogenase (ADH), subsequently to acrylic acid by aldehyde dehydrogenase (ALDH). Since ethanol could compete the same enzymes to be metabolized in the liver, we have determined the plasma concentrations of allyl alcohol and ethanol followed by combined treatment. Pretreatment of rats with 2g/kg ethanol followed by ip administration of 40mg/kg allyl alcohol increased the lethality significantly. Determination of in vivo blood concentrations revealed that ethanol pretreatment caused the apparent decrease in allyl alcohol clearance, whereas acetaldehyde level in blood increased significantly by allyl alcohol treatment, as determined by head space GC analysis. Treatment of 4-methylpyrazole, an inhibitor of ADH, delayed allyl alcohol elimination significantly and reduced its lethality. Collectively, these findings suggested that reduction of allyl alcohol clearance in the presence oj ethanol was mediated through ADH competitive inhibition.

• Korean Journal of Environmental Biology
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• v.19 no.2
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• pp.147-152
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• 2001

Whether the pretreatment of sublethal arsenic or cadmium may prevent from lethality of arsenic or cadmium to mice, respectively, and also the protection against to lethality of arsenic or cadmium which might be induced by pretreatment of arsenic or cadmium may be related with their hepatic glutathione contents were investigated. When sodium arsenite or cadmium chloride was subcutaneously injected to mice (ICR strain) using lethal doses, all mice of both group were killed. The mortality of mice which were subsequently injected with lethal arsenic 24 hours after pretreatment of sublethal arsenic was decreased, and the same result was obtained in the case of cadmium. Sublethal pretreatment of arsenic or cadmium prior to lethal arsenic or cadmium treatment to mice, respectively, didn't decrease hepatic glutathione contents of the survived mice, while decreases of that contents in liver were observed in the mice just after they died. Cadmium pretreatment decreased mortality of mice which subsequently injected with lethal arsenic, while arsenic pretreatment didn't protect against cadmium lethality. These results indicate that protection against arsenic or cadmium lethality to mice induced by pretreatment of sublethal arsenic or cadmium may be directly related to other factors induced by sublethal camium pretreatment, not to hepatic glutathione contents.

• BMB Reports
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• v.38 no.1
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• pp.89-96
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• 2005

Earlier, we reported that the bacteriophage $\lambda$ P gene product is lethal to Escherichia coli, and the E. coli rpl mutants are resistant to this $\lambda$ P gene-mediated lethality. In this paper, we show that under the $\lambda$ P gene-mediated lethal condition, the host DNA synthesis is inhibited at the initiation step. The rpl8 mutation maps around the 83 min position in the E. coli chromosome and is 94% linked with the dnaA gene. The rpl8 mutant gene has been cloned in a plasmid. This plasmid clone can protect the wild-type E. coli from $\lambda$ P gene-mediated killing and complements E. coli dnaAts46 at $42^{\circ}C$. Also, starting with the wild-type dnaA gene in a plasmid, the rpl-like mutations have been isolated by in vitro mutagenesis. DNA sequencing data show that each of the rpl8, rpl12 and rpl14 mutations has changed a single base in the dnaA gene, which translates into the amino acid changes N313T, Y200N, and S246T respectively within the DnaA protein. These results have led us to conclude that the rpl mutations, which make E. coli resistant to $\lambda$ P gene-mediated host lethality, are located within the DNA initiator gene dnaA of the host.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.89-94
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• 1998

Marine sponges are recognized as a plentiful source of diverse biologically active secondary metabolites. Recently, we have initiated a research to discover antitumor constituents from the marine sponges collected from Korean Waters. Marine sponges collected from the South Sea of Korea were screened for several biological activities including such as brine shrimp lethality and cytotoxicity. Significant brine shrimp lethality was detected in the crude extract of a two-sponge association of Poecillastra sp. and Jaspis sp. A cross-section of this sample showed two layers of morphologically distinct sponges. The thin and dirty yellow outer layer was identified as Poecillastra sp. (Pachastrellidae), the surface of which was very rough. The light-grey inner layer was identified as Jaspis sp. (Jaspidae), the surface of which was smooth. This two-sponge association appears to be consistent as these sponges were always found in associated form regardless of collection site or collection period. Investigation of the bioactive constituents monitored by brine shrimp lethality assay led to the isolation of pectenotoxin II (PTX2) and psammaplin A as causative compounds for the brine shrimp lethality. $^1$H- and $\^$13/C-nmr signals of PTX2 was fully assigned utilizing TOCSY, HETCOR, Long-range HETCOR, and Homonuclear J-resolved 2D experiments. PTX2 displayed very potent and selective cytotoxicities in the 60 cell line panel antitumor assay at the NCI. PTX2 has progressed to acute toxicity determination and in vivo antitumor assay at the NCI (Table 1). However, significant in vitro antitumor activity of PTX2 can not be affirmed in the in vivo assay.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.134-141
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• 1989

The present investigation aims at elucidating a possible mechanism of heat inactivation of SCK ceils by comparing the kinetics of cell lethality and protein degradation in the presence of heat protector or heat sensitizer. The effect of heat sensitizer and protector was exhibited in both cell survival and protein degradation kinetics, the magnitude of the effect being much profound for the protector compared to the sensitizer. A conclusion to he drawn from the present experiment is that there is no direct correlation between cell lethality and protein degradation. Rather, protein degradation, which might occur in the membrane, causes cell inactivation indirectly, possibly by altering the cellular environment. Accordingly, further studies are needed to get insight into the mechanism of cell inactivation by hyperthermia.

• Strategy21
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• s.44
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• pp.28-53
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• 2018

The U.S. has recently developed Free and Open Indo-Pacific strategy and Distributed Lethality strategy based on a common perception that they are responding to China's threats. In the future, it is anticipated the following. Strengthen cooperation of the U.S.-India-Vietnam navy, Maximizing the combined combat power between the U.S. and regional navies, Improving its ability to restore damage control, Economic cooperation between the Pacific and Indian countries. The meanings given to the Korean navy are as follows. First, South Korea should pursue cooperation with the Indian Navy, which will grow into a regional balance on China's growth. The growth of the Indian navy is expected to increase cooperation with other Pacific countries. The government should seek ways to promote cooperation with india navy in various fields. Secondly, it is a joint drill between the U.S. Navy and the Korean Navy. Recently, the Korea-U.S. joint drill has not been conducted and many changes are expected to be made regarding the implementation of the joint drill in the future. Therefore, it is necessary to respond to possible changes in the naval relationship between Korea navy and the U.S. navy Also, due to distributed lethality strategy, preparations for operations and training with U.S.navy will be necessary. Lastly, it should contribute to cooperation among regional countries in preparation for maritime territorial disputes. The growth of the Chinese navy and the territorial disputes in the East and South China sea has raised the possibility of accidental military clashes at sea. Therefore, the government should make efforts to create multilateral security cooperation systems that can continue to promote the prevention of armed conflict.

• Molecules and Cells
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• v.26 no.2
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• pp.171-174
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• 2008

Flavone (2-phenyl chromone) is a well-known plant flavonoid, but its bioactivity has been little explored. Treatment of Caenorhabditis elegans or C. brissage with flavones induced embryonic and larval lethality that was pronounced in early larval stages. This anti-nematodal effect was also observed in the pinewood nematode, B. xylophilus. $LD_{50}$ values were approximately $100{\mu}M$ for both B. xylophilus and C. elegans. Our results indicate that flavone is an active nematicidal compound that should be further investigated with the aim of developing a potent drug against B. xylophilus.