• The Korean Journal of Zoology
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• v.26 no.1
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• pp.19-28
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• 1983

Alkaline elution profiles showed that the frequency of DNA single strand breaks associated with DNA-protein crosslinks in cells treated with both an inducing dose of MMC $(MMC_1)$ and a challenge dose of MMC $(MMC_2)$ was slightly less than that in cells treated with MMC alone. The amount of unscheduled DNA synthesisi in cells treated with both $MMC_1$ and $MMC_2$ was greater than that in cells treated with MMC alone. This enhancement of exicision repair detected by UDS autoradiography and alkaline elution, was not observed, when cells were incubated with cyclohexmide between the two treatments of $MMC_1$ and $MMC_2$. These results suggest that MMC-damaged DNA from Chinses hamster cells is repaired by excision repair mechanisms that require de novo protein synthesis for enhancement, and that an inducible repair mechanism may exist in CHO cells.

• Korean Journal of Pharmacognosy
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• v.23 no.4
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• pp.248-258
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• 1992

The studies were conducted to investigate the combined effects of several combined preparation of crude drugs and mitomycin C(MMC). The combined effects on the proliferation of HepG2, A549, KHOS-Np, A431 and HeLa cells were estimated by MTT colorimetric assays. Sa Kunja Tang(SKT), Boyang Hwanoh Tang(BHT) and Hyulbu Choogo Tang(HCT) inhibited the proliferation of A549 and HeLa cell. The inhibitory action of MMC was increased by the combined treatment of SKT and MMC, and Sa Mul Tang(SMT) and MMC, respectively. When the mice were treated by MMC, the number of leukocyte was decreased significantly at the 3rd day, but recovered at the 7th day. In the groups of MMC treated with SKT or HCT, the number of leukocyte was increased significantly that the group of MMC treated only at the 1st and 3rd day. The combined treatment of SKT, SMT, BHT, HCT and MMC retained the spleen weight of mice at the level of normal mice, but decreased the thymus weight of mice. The combined treatment of SKT, SMT, BHT, HCT and MMC increased the number of PFC significantly than the MMC treated group. The combined treatment of SKT, SMT, BHT, HCT and MMC increased the T cell proliferation significantly thant the MMC treated group.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.320-321
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• 2020

본 논문은 AC 계통 불평형 발생 시 출력전력의 동요를 저감시키기 위한 POD 전략을 수행하는 MMC-HVDC 시스템의 내부 동적상태를 분석하였다. POD 전략을 통해서 MMC 출력전류의 역상분을 제어하여 계통에 주입되는 유효 전력의 발진을 제거함으로써, MMC-HVDC 시스템이 연계된 인근 계통에 공급 신뢰도를 향상시킬 수 있다. POD 전략에서 유효 전력만 출력할 경우, MMC의 각 상에는 동일한 전력이 흐른다. 반면, 계통 전압 보상을 위해서 무효 전력을 동시에 공급할 경우, 각 상에 흐르는 전력은 불균형해지기 때문에 MMC의 암전류 불평형이 발생하여 스위치 소자의 정격 용량 및 열 스트레스를 증가 시켜 MMC의 안정성을 저해시킨다. 본 논문은 POD 전략을 수행하기 위해서 무효 전력이 MMC 암 전류에 미치는 영향을 분석하였으며, 200 MW MMC-HVDC 모델을 바탕으로 PSCAD/EMTDC 시뮬레이션 툴을 이용하여 분석 결과를 검증하였다.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.4
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• pp.175-181
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• 2015

In order to examine the effect of Smilax china L. (SC) extract on the cytotoxicity of methymercuric chloride (MMC), allergic contact dermatitis, The cytotoxicity of MMC was assessed after cultured NIH3T3 fibroblasts were treated with various concentrations of MMC for 72 hours. And also, the following results were obtained by measuring the antioxidative effect of SC extract on the cytotoxicity of MMC. In this study, MMC remarkably decreased the cell viability of NIH3T3 fibroblasts in a dose-dependent manner, and MMC was seen to be highly-toxic below 100 uM of $XTT_{50}$ value. In addition, the toxicity of MMC was involved in oxidative stress via a blockage of MMC-induced cytotoxicity by vit. E as antioxidant. In the protective effect of SC extract on MMC-induced cytotoxicity, SC extract defended the cytotoxicity of MMC by a significant increase of cell viability which was decreased by MMC-induced cytotoxicity. It also showed antioxidative effects such as electron donating ability (EDA), superoxide dismutase (SOD)-like activity (SLA) and the lipid peroxidation activity (LPA). From these results, the natural component as SC extract may be a putative resource as the antioxidative agent for the treatment of inflammatory skin disease associated with the oxidative stress.

• The Journal of Internal Korean Medicine
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• v.15 no.1
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• pp.60-79
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• 1994

The studies were conducted to investigate the combined effects of Tonics and Mitomycin C(MMC). The effects of Tonics and MMC on the proliferation of Molt-4 cells, human leukemic cell line, and activation of human lymphocytes were estimated by MTT colorimetric assays. Selected medicines among 9 kinds of Tonics by results of MTT assays were treated with MMC in mice. The Tonics itself enhanced the proliferation of Molt-4, but the anti-proliferative effect of MMC was not intercalated by the combined treatment of Tonic and MMC. Inhibitory action of MMC was augmented by Sa Kun Ja Tang(SKT). This result was due to the inhibition of DNA synthesis. Among 9 kinds of Tonics, Sip Jean Dae Bo Tang(SDT), Saeng Maek San(SMS) and Kwi Bi Tang(KBT) did not inhibit the action of MMC, but activated lymphocytes. When the mice were treated by MMC, the number of leukocytes was decreased significantly at the 1st day, but recovered at the 7th day. In the groups of MMC treated with SDT or KBT, the number of leukocytes was increased significantly than the group of MMC treated only at the 3rd day. Combined treatment of the Tonics(SDT, SMS) and MMC retained the body weight of mice at the level of normal mice. SDT, SMS and KBT did not change the number of plaque forming cells(PFC), but MMC treated group decreased the number of PFC. The combined treatment of MMC and SDT increased the number of PFC significantly than the MMC treated group. SDT, SMS and KBT did not influence the proliferation of T cells, but MMC treated group decreased the proliferation of T cells. The combined treatment of MMC and those tonics increased the T cell proliferation significantly than the MMC treated group. In conclusion, the results presented in this paper suggest that SDT, SMS and KBT can recover the side effects of MMC, such as weight loss, leukopenia and immunosuppresion, without any intercalating the anti-proliferative action of MMC in vivo.

• Biomedical Science Letters
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• v.13 no.4
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• pp.355-360
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• 2007

In order to evaluate on the cytotoxicity of methyl mercury (MM) and antioxidant effect of phenolic compound, poncirin against MM-induced cytotoxicity, XTT assay was performed to determine the cell viability after human skin fibroblasts (Detroit 51) were grown in the media containing various concentrations of methylmercuric chloride (MMC). And also, the antioxidant effect of poncirin on the cytotoxicity induced by MMC was examined by cell viability and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in these cultures. MMC decreased cell viability in dose-dependent manner in these cultures and the midcytotoxicity value was determined at concentration of 30 ${\mu}M$ MMC after human skin fibroblasts were treated with $10\sim50{\mu}M$ MMC for 72 hours, respectively. MMC was highly toxic on cultured human skin fibroblasts by toxic criteria. MMC-mediated cytotoxicity was related with oxidative stress by the diminution of toxic effect according to the treatment of vitamin E. In the antioxidant effect of poncirin, it showed vitamin E-like DPPH radical scavenging activity at 90 ${\mu}g/ml$ poncirin and also, remarkably increased cell viability compared with MMC-treated group. From these results, it is suggested that MMC-mediated cytoxicity was highly toxic and was related with oxidative stress in cultured human skin fibroblasts, and also phenolic compound such as poncirin showed the protection on MMC-induced cytotoxicity by antioxidant effect in these cultures.

• The Korean Journal of Zoology
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• v.20 no.2
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• pp.93-99
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• 1977

Dose response forDNA repair synthesis induced by various concentrations of MMC (0.05 $\\sim$ 0.5 $\\mu$g/ml) in HeLa $S_3$ cells was not dose-dependent and the amounts of it were relatively lower, representing $7\\sim9%$ of total DNA synthesizing cells in $0.1\\sim0.5 \\mug/ml$ concentrations. Time dependence study showed that MMC-induced DNA repair synthesis occurred as long as for 24 hours with similar incidences in all time courses. Pretreatment with BUdR was found to have a sensitization effect on MMC-induced DNA repair synthesis, but that with IUdR was not. Combined treatment with BUdR of IUdR and MMC suppressed remarkably the semiconservative DNA synthesis especially at later time course. These results seem to suggest that damages induced in DNA by MMC might be repaired by both fast and slow excision processes.

• Biomedical Science Letters
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• v.12 no.4
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• pp.451-455
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• 2006

It is demonstrated that inorganic mercury has cytotoxic effect on glial cells. Recently, oxygen radicals is involved in methylmercuric chloride (MMC)-induced cytotoxicity. But, the toxic mechanism of MMC is left unknown. The purpose of this study was to examine the cytotoxicity of MMC on $C_6$ glioma cells. The cytotoxicy was measured by cell viability using XTT assay in $C_6$ glioma cells. Colorimetric assay is regarded as a very sensitive screening method for the determination of the cell viability on various agents. In this study, MMC decreased cell viability according to the dose- and time dependent manners after $C_6$ glioma cells were grown with various concentrations of MMC for 48 hours. In the protective effect of allopurinol on MMC-induced cytotoxicity, allopurinol was effective in the prevention of MMC-induced cytotoxicity in these cultures. These results suggest that MMC has highly cytotoxic effect on $C_6$ glioma cells by the decrease of cell viavility, and free radical scavenger such as allopurinol was effective on organic mercury-induced cytotoxicity in these cultures.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.351-352
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• 2012

본 논문에서는 최근 직류송전용 컨버터로 많은 관심이 집중되고 있는 MMC(Modular Multi-level Converter)에 대해서 소개하고 있다. 대용량 전압원 컨버터로 MMC가 적합한 이유에 대해서 설명하고, MMC의 동작원리, SM(Sub-Module) dc capacitor voltage balancing 기술, 전체 제어 시스템에 대해 자세하게 설명하고 있다. 제안하는 MMC는 Staircase Modulation 방식으로 사인파형에 가까운 출력전압을 형성하고, Sorting 알고리즘을 구현하여 개별 SM의 커패시터 전압이 균등하게 일정 값을 유지하도록 하였다. 제안하는 MMC의 성능평가를 위하여 PSCAD/EMTDC 프로그램을 이용하여 3상 11-level MMC를 모의하였다.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.1003-1007
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• 1995

The effect of brown rice extract on mitomycin C(MMC)-induced chromosome aberration was examined in cultured Chinese hamster lung(CHL) cells, after induction of chromosome aberration and mitotic index in CHL cells cultured with MMC were observed. There were no significant differences between mitotic indices of CHL cells treated with DMSO, and MMC and brown rice extract. The frequency of chromosome aberration showed dose-dependent relationship in CHL cells treated with $0.2{\sim}3.0\;{\mu}g$/assay of MMC. But chromosome aberrations could not be assayed Our to cytotoxicity of MMC when its concentrations were above $3.0\;{\mu}g$/assay. Chromatid type, especially gap and break, of chromosome aberration were most frequently observed. When CHL cells treated with $2.0\;{\mu}g$/assay of MMC and brown rice extracts of concentration ranging $0.75{\sim}10.0\;{\mu}g$/assay were incubated, frequencies of chromosome aberration induced by MMC were significantly decreased at above concentrations(p<0.01, p<0.05). As concentration of brown rice extract was increased, frequencies of chromosome aberration was decreased $7{\sim}30%$, in some irregularity.