• Journal of Magnetics
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• v.8 no.1
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• pp.1-6
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• 2003

The new class of $Gd_5(Si_xGe_{1-x})_4$ compounds undergoes a simultaneous magnetic/structural phase transition giving a high level of strain that can be induced either by change in temperature or by application of a magnetic field. Profound changes of structural, magnetic, and electronic changes occur in the $Gd_5(Si_xGe_{1-x})_4$ system lead to extreme behavior of the material such as the giant magnetocaloric effect, colossal magnetostriction, and giant magnetoresistance. These unique material characters can be utilized for various applications including magnetic solid refrigerants, sensors, and actuators.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.171-171
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• 1993

발암물질의 조기검색법을 개발하고자 변이원성 물질의 스크리닝법으로 널리 사용되고 있는 Ames test 및 chromosomal aberration test를 본 연구에서 개발하고자 하는 DNA 및 Protein-adduct 형성시험법과 비교 연구하였다. 벤조피렌과 아플라톡신 B$_1$을 모델 발암물질로 하여 실시한 Ames test에서는 두 화합물 모두 양성을 나타냈으나 용량-반응 관계가 뚜렷하지 않았다. 또한 고농도에서는 시험물질의 독성체 의해 정상적인 Ames test의 수행이 어려됐다. Chromosomal aberration test에서도 Ames test와 비슷한 결과를 나타냈으며 특히 고농도에서 시험을 실시했을 경우 Ames test에서와 마찬가지로 세포독성의 현상이 관찰되었다. 그러나 본 연구에서 새로이 개발한 DNA 및 Protein-adduct형성 시험법은 저농도에서 고농도에 이르기까지 뚜렷한 용량-반응 관계를 나타냈으며 Ames test 및 chromosomal test에서 일어날 수 있는 false positive나 false negative의 결과를 가져다 줄 우려가 없다. 또한 시험시간이 1-2시간 정도 소요되므로 기존의 방법보다 시험시간을 약 40배 가량 단축시킬 수 있었다.

• Journal of Life Science
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• v.5 no.3
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• pp.121-125
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• 1995

To determine whether the omega 3 family, linolenic acis(LnA) is effective to inhibit carcinogens/mutagens-induced mutagenesis, we employed the Ames test using Salmonella typhimurium strain of TA100 and the SOS chromotest using Escherichia coli PQ37 strain. The inhibitory effect of LnA shown in the Ames assaying system was 95%, 78% and 73% when the mutagenicities were mediated by AFB$_{1}$, MNNG and 4-NQO, respectively. LnA shows a strong antimutagenic activity against indirect mutagen of AFB$_{1}$, whereas the same concentration of LnA exhibited weaker inhibitory effects on the direct mutagen of MNNG and 4-NQO than that of AFB$_{1}$. However. LnA reduced more than 80% of SOS responses induced by MNNG and 4-NQO when the adding concentration increased to 5%. We conclude that LnA contains in vitro antimutagenic properties and that this finding warrants further investigation both in vitro and in vivo to assess its possible chemotherapeutic potential.

• Environmental Mutagens and Carcinogens
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• v.25 no.1
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• pp.6-12
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• 2005

Many compounds might become activated after absorption of UV light energy. In some cases, the resulting molecule may undergo further biological reaction of toxicological relevance related especially to the photo-carcinogenicity resulting from photo-genotoxicity. However, no regulatory requirements have been issued with the exception of guideline issued by the Scientific Committee of Cosmetology, Commission of the European Communities (SCC/EEC) on the testing of sunscreens for their photo-genotoxicity. Thus, the objectives of this study are to investigate the utility of photo-Ames assay for detecting photo-mutagens, and to evaluate its ability to predict rodent photo-carcinogenicity. Photo-Ames assay was performed on five test substances that demonstrated positive results in photo-carcinogenicity tests: 8-methoxypsoralen (photoactive substance that forms DNA adducts in the presence of ultraviolet A irradiation), chlorpromazine (an aliphatic phenothiazine an a-adr-energic blocking agent), lomefloxacin (an antibiotic in a class of drugs called fluoroquinolones), anthracene (a tricyclic aromatic hydrocarbon a basic substance for production of anthraquinone, dyes, pigments, insecticides, wood preservatives and coating materials) and retinoic acid (a retinoid compound closely related to vitamin A). Out of 5 test substances, 3 showed a positive outcome in photo-Ames assay. With this limited data set, an investigation into the predictive value of this photo-Ames test for determining the photo-carcinogenicity showed that photo-Ames assay has relatively low sensitivity (the ability of a test to predict carcinogenicity). Thus, to determine the use of in vitro genotoxicity tests for prediction of carcinogenicity,' several standard photo-genotoxicity assays should be compared for their suitability in detecting photo-genotoxic compounds.

• Korean Journal of Pharmacognosy
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• v.34 no.1 s.132
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• pp.80-85
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• 2003

Water extract from Astragali Radix (AR) was tested for the safety using Ames, Bacillus subtilis Rec, and umu gene expression mutagenicity tests. Mutagenic activity in any assays we tested was not found. In Ames test, Salmonella typhimurium TA98 and TA 100 were used to identify mutagenic property, and the number of histidine revertants was measured. In the Recassay, Bacillus subtilis ${H-17(Rec^+)\;and\;M-45(Rec^-)}$ strains were used to test DNA damage activity. In the SOS umu test, Salmonella typhimurium TA1535 containing plasmid pSK1002 was used as a test strain, and we monitored the levels of umu operon expression by measuring the ${\beta}-galactosidase$ activity. From the results, there was no DNA damage and mutagenicity of AR. Hepatotoxicity of AR to female ICR mice was also monitored by the measurements of s-GOT, s-GPT, LDH activities after oral feeding for 15 days. AR was not shown any significant changes of s-GOT, s-GPT and LDH activities in mice sera.

• Preventive Nutrition and Food Science
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• v.4 no.1
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• pp.38-42
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• 1999

Antimutagenic effects of 5 kinds of kochujang(Korean red pepper soybean paste) samples compared with doenjang(Korean soy paste) were studied using the Ames test with Salmonella typhimurium TA100 and the SOS chromotest, with E. Coli PQ37. Th eantimutatenic effects of methanol extracts from red pepper powder and meju(fermented soybean) powder, the major ingredients of the kochujang,were also evaluated for the mutagenicity of aflatoxin B1 (AFB1) in the Ames assay. The methanol extracts from the kochujang samples showed lower antimutagenicities than those of doenjang against AFB1 and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the Ames assay. Traditional kochujang I and II exhibited strong antimutagenic activity against AFB1 and MNNG. The traditional kochujang samples against MNNG were aslo observed in the SOS chromotest system with the same fashions as shown in the Ames mutagenicity test. The methanol extracts from meju powder had the strongest inhibitory effects on mutabenicity induced by AFB1, however, those form red pepper powder showed lower inhibition rate than kochujang. These results suggest that traditional kochujang exhibit higher antimutagenic acitivity than the commercial variety, and that meju powder seems to be one of the major antimutagenic components in kochujang.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.498-504
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• 1992

In order to investigate the antimutagenicity of the sweet potato enzymatic browning reaction products (SPEBRP) were studied the DNA breaking action, spore rec assay and Ames test. In the DNA breaking action of reaction mixture of SPEBRP and polyphenol compounds with an agarose horizonal electrophoresis, catechol (CAT)-SPEBRP and hydroxyhydroquinone (HHQ)SPEBRP inhibited DNA breaking effect in the presence of $Fe^{2+}$. In the spore ree assay using Bacillus subtilis H17(rec+) and M45(rec-), 3,4-dihydroxytoluene (DHT)-SPEBRP showed strong antimutagenic effects on MNNG. In the Ames test using Salmonella tYPhimurium TA 98 and TA 100, pyrogallol(PYR)-, 3,4-dihydroxytoluene (DHT)- and hydroxyhydroquinone (HHQ)-SPEBRPs suppressed about 67%, 71% and 63% in the mutagenesis induced by Benzo($\alpha$)Pyrene(B($\alpha$)p).

• Environmental Mutagens and Carcinogens
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• v.20 no.1
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• pp.21-25
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• 2000

Recently there is increasing interest in the use of structure activity relationships for predicting the biological activity of chemicals. The reasons for the interest include the decrease cost and time per chemical as compared with animal or cell system for identifying toxicological effects of chemicals and the reduction in the use of animals for toxicological testing. This study is to test the validity of the mutagenicity data generated from QSAR (Quantitative Structure Activity Relationship) program. Thirty chemicals, which had been evaluated by Ames test during 1997-1999, were assessed with TOPKAT QSAR mutagenicity prediction module. Among 30chemicals experimented, 28 were negative and 2 were positive for Ames test. On the contrary, 23 chemicals showed the high confidence level indicating high prediction rate in mutagenicity evaluation, and 7 chemicals showed the lsow to moderate confidence level indicating low prediction in mutagenicity evaluation. Overall mutagenicity prediction rate was 77% (23/30). The prediction rates for non-mutagenic chemicals were 79% (22/28) and mutagenic chemicals were 50% (1/2). QSAR could be a useful tool in providing toxicological data for newly introduced chemicals or in furnishing data for MSDS or in determining the dose in toxicity testing for chemicals with no known toxicological data.

• Journal of Food Hygiene and Safety
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• v.11 no.1
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• pp.17-24
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• 1996

The genotoxicity of combinations of four p-oxybenzoic acids (methyl paraben, ethyl paraben, isopropyl paraben, butyl paraben) and benzoic acid had been evaluated. The in vitro Ames test using Salmonella typhimurium (TA 98, TA 100, 1535, TA 1537) and the invivo micronucleus assay using mouse peripheral blood were performed. Methyl paraben plus benzoic acid, ethyl paraben plus benzoic acid, and ethl paraben plus butyl paraben slightly increased the frequency of microuncleated reticulocytes in the high doses, but were negative in Ames test with Salmonella typhimurium with and without rat liver microsomal activation. The other combinations tested were negative in Ames test and did not show any clastogenic effect in micronucleus test. These results suggest that genotoxicity can produced by th combination of p-oxybenzoic acid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.930-935
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• 2004

This study was carried out to determine the antimutagenic effect of soybean sprouts cultured in water containing germanium by Ames test and SOS chromotest. Germanium significantly inhibited the mutagenicity induced by aflatoxin B$_1$ (AFB$_1$) in Salmonella typhimurium TA100 by Ames test, and 4-nitroquinoline-N-oxide (4-NQO) in SOS chromotest. Juice from germanium treated soybean sprouts (GTS) inhibited 57∼75% mutagenicity induced by AFB$_1$, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 4-NQO compared with 20∼48% inhibition rate of control soybean sprouts (germanium non-treated soybean sprouts, GNTS) in the Ames test. Also, methanol extracts from GTS inhibited 65% mutagenicity induced by AFB$_1$ in Salmonella typhimurium TA100, and 51% mutagenicity by 4-NQO in SOS chromotest. Therefore, it suggests that GTS has strong potential antimutagenic effect.