• Journal of Radiation Protection and Research
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• v.36 no.1
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• pp.1-7
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• 2011

A simple mathematical model of simultaneous combined action of environmental agents has been proposed to describe the synergistic interaction of microwave and high ambient temperature treatment on animal heating. The model suggests that the synergism is caused by the additional effective damage arising from an interaction of sublesions induced by each agent. These sublesions are considered to be ineffective if each agent is taken individually. The additional damage results in a higher body temperature increment when compared with that expected for an independent action of each agent. The model was adjusted to describe the synergistic interaction, to determine its greatest value and the condition under which it can be achieved. The prediction of the model was shown to be consistent with experimental data on rabbit heating. The model appears to be appropriate and the conclusions are valid.

• Archives of Pharmacal Research
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• v.22 no.3
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• pp.232-236
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• 1999

In this study, we present evidence that cotreatment of aloesin and arbutin inhibits tyrosinase activity in a synergistic manner by acting through a different action mechanism. Aloesin or arbutin similarly inhibited enzyme activity of human- and mushroom-tyrosinases with an IC50 value of 0.1 or 0.04 mM, respectively. Lineweaver-Burk plots of the enzyme kinetics data showed that aloesin inhibited tyrosinase activity noncompetitively with a Ki value of 5.3 mM, whereas arbutin did it competitively (Maeda, 1996). We then examined whether cotreatment of these agents inhibits the tyrosinase activity in a synergistic manner. The results showed that 0.01 mM aloesin in the presence of 0.03 mM arbutin inhibited activity of mushroom by 80% of the control value and the reverse was also true. The inhibitory effects were calculated to be synergistic according to the B rgi method. Taken together, we suggest that aloesin along with arbutin inhibits in synergy melanin production by combined mechanisms of noncompetitive and competitive inhibitions of tyrosinase activity.

• Journal of Haehwa Medicine
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• v.4 no.1
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• pp.211-223
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• 1995

The antitumor effect of 柴胡(Bupleuri Radix : BP), 茵陳(Artemisiae capillaris Herba; ACH) 및 蒲公英(Taraxaci Herba; TH) and 蒲公英 EE層(Ethyl ether layer of TH; EETH) on human hepatocytes such as Hep G2, PLC and Hep 3B, and synergistic action with the anticancer drugs, that is, mitomycin(MMC), cisplatin(CPT) and 5-fluorouracil(5-FU) were studied by the method of MTT. The results were obtained as follows: 1. $IC_{50}$ against Hep G2, PLC and Hep 3B was $15.5{\mu}g/ml$, $25.4{\mu}g/ml$ and 31.25 in MMC, $92.5{\mu}g/ml$, $50.2{\mu}g/ml$ and $62.5{\mu}g/ml$ in CPT and $125{\mu}g/ml$ in 5-FU respectively. 2. Cytotoxic effect on Hep G2 was obvious in BP-treated group, synergistic action was most effective in TH-treated group or with MMC. 3. Cytotoxic effect on Hep 3B was obvious in ACH-treated group, synergistic action was most effective in ACH-treated group or with MMC. 4. Cytotoxic effect on PLC was obvious in ACH-treated group, synergistic action was most effective in TH-treated group or with MMC. From above results it was concluded that ACH showed the best antitumor effect against PLC and Hep 3B, BP aganst Hep G2 and also synergistic effect was most effective with MMC, which indicates that it is necessary to seperate the antitumor substances in ACH.

• Korean Journal of Environmental Biology
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• v.27 no.2
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• pp.140-145
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• 2009

All organisms are being exposed to harmful factors present in the environmental. The combined action of various factors is a distinguishing feature of modern life. An interaction between two chemicals is considered as synergistic when the effect produced is greater than the sum of the two single responses. The biological effects due to the combined action of ionizing radiation with the other factor are hard to estimate and predict in advance. In the current study, we investigated the synergistic effects between ionizing and $HgCl_2$ using fish hepatoma cells (PLHC-1 cells). The results showed a dramatic decrease of cell viability after simultaneous treatment of PLHC-1 cells with ionizing radiation and $HgCl_2$. Neiither of the two had any cytotoxic effect when treated alone. The cytotoxicity of ionizing radiation was enhanced in the presence of $HgCl_2$. The synergistic effects were observed after exposure of the PLHC-1 cells to ionizing radiation combined with $HgCl_2$. The synergistic interaction was due to an increase of irreversibly damaged cells after the combined exposure. Analysis of the extent of synergistic interaction enables to make quantitative estimation of irreversibly damaged cells after the combined exposure. The present study suggests that PLHC-1 cells can serve as rapid screening tools for detecting the toxicity of harmful factors.

• Korean journal of applied entomology
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• v.28 no.1
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• pp.32-36
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• 1989

The joint toxic action of mixtures of cypermethrin or pirimicarb with one of other insecticides (acephate, cypermethrin, demeton-S-methyl and pirimicarb) on the cypermethrin or picimicarb-selected green peach aphid (Myzus persicae Sulzer)was investigated. The responses depended on the choice and ratios of insecticide combination. In the cypermethrin-selected strain bioas-say, mixtures of test insecticides showed no synergistic effect. On the other hand, the maxi-mum synergistic effects for the pirimicarb-selected strain were obtained at the 8 : 2 ratio of pirimicarb and demeton-S-methyl exhibited antagonistic effect.

• Food Science and Biotechnology
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• v.18 no.4
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• pp.904-909
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• 2009

The beneficial effects derived from consuming natural antioxidants may not depend on the action of an individual antioxidant, but rather on the concerted action of several antioxidants naturally present. The aim of this study was to determine the concentrations and combinations of antioxidants that can produce synergistic effects (SyEs). Quantification of the lipoperoxyl radical scavenging capacity of antioxidants was carried out in a homogeneous model system where the free radicals were produced by the oxidation of methyl linoleate, initiated by the 2,2'-azobis (2,4-dimethylvaleronitrile). The greatest SyE (2.21, p<0.05) was seen in mixtures of all 4 antioxidants when used with concentrations of 15 ${\mu}M$ lycopene, 2.5 ${\mu}M$ vitamin E, 0.16 ${\mu}M$ vitamin C, and 10 ${\mu}M$ ${\beta}-carotene$. Doubling the vitamin E concentration from 2.5 to 5.0 ${\mu}M$ in the mixture with all 4 antioxidant reduced the SyE to 1.69 (p<0.05). Other combinations produced synergistic effects that ranged from 1.28 to 1.41.

• Korean Journal of Microbiology
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• v.5 no.1
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• pp.7-14
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• 1967

The synergistic actions of certain antimetabolic agents for Saccharomyces cerevisiae and Lactobacillus plantarum on radiation sterilization have been studied. The used chemical agents are sorbic acid, vitamin-$K_3$, dehydroacetic acid, p-oxybutyl benzoate and nitrofurazone, those are the permitted as food preservatives. Experimental results are as following, 1) Survival fraction of yeast which was gamma-irradiated and influenced by sorbic acid or vitamin $K_3$ is much reduced than that of only irradiated respectively. 2) It seems like that the used chemicals acts synergistically on radiation sterilization. Sodium-dehydroacetate and p-oxybutyl benzoate are proved to be also synergistic but weakly. 3) Survival fraction of Lact. plantarum which was gamma-irradiated and influenced by sorbic acid, dehydroacetic acid or nitrofurazone respectively much reduced than that of only irradiated group, it can be estimated as synergistic action of chemical affected on radiation sterilization. 4) It was found that nutrient componets can affect radiation sterilization of microorganisms protectively.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.176-183
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• 1993

These sutdies were conducted to investigate the joint toxic action of mixtures of several acaricides including amitraz, bifenthrin, propargite, fenbutatin dxide and bxide dicofol to the field-collected strian of Tetranychus urticae. The synergistic action of acaricidal mixtures was greatly varied with the kind of acaricide combinations and their mixture ratios. The combinations of amitraz with each of the tested acaricides were synergized at the given mixture ratios. The higher synergistic action in the each combination was observed at 2 : 8 ratio of amitraz and bifenthrin, 8 : 2 ratio of amitraz and fenbutatin oxide, 4 : 6 ratio of amitraz and propargite and 6 : 4 ratio of amitraz and dicofol.

• Korean Journal of Environmental Biology
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• v.20 no.4
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• pp.277-286
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• 2002

An increase in the overall biological effect under the combined action of ionizing radiation with another inactivating agent can be explained in two ways. One is the supposition that synergism may attribute to a reduced cellular capacity of damn-ge repair after the combined action. The other is the hypothesis that synergism may be related to an additional lethal or potentially lethal damage that arises from the interaction of sublesions induced by both agents. These sublesions ave considered to be in-effective when each agent is applied separately. Based on this hypothesis, a simple mathematical model was established. The model can predict the greatest value of the synergistic effect, and the dependence of synergy on the intensity of agents applied, as well. This paper deals with the model validation and the peculiarity of simultaneous action of various factors with radiation on biological systems such as bacteriophage, bacterial spores, yeast and mammalian cells. The common rules of the synergism aye as follows. (1) For any constant rate of exposure, the synergy can be observed only within a certain temperature range. The temperature range which synergistically increases the effects of radiation is shifted to the lower temperature fer thermosensitive objects. Inside this range, there is a specific temperature that maximizes the synergistic effect. (2) A decrease in the exposure rate results in a decrease of this specific temperature to achieve the greatest synergy and vice versa. For a constant temperature at which the irradiation occurs, synergy can be observed within a certain dose rate range. Inside this range an optimal intensity of the physical agent may be indicated, which maximizes the synergy. As the exposure temperature reduces, the optimal intensity decreases and vice versa. (3) The recovery rate after combined action is decelerated due to an increased number of irreversible damages. The probability of recovery is independent of the exposure temperature for yeast cells irradiated with ionizing or UV radiation. Chemical inhibitors of cell recovery act through the formation of irreversible damage but not via damaging the recovery process itself.

• Journal of Plant Biology
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• v.10 no.3_4
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• pp.1-3
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• 1967

Observations were made on Crinum and Catharanthus pollen growth in artificial media by an ultraviolet transmission fluorescence microscope showing synergistic effect on pollen growth with calcium (Ca) and aureomycin. Bright yellow fluorescence of aureomycin enabling to trace out at tissue or cellular level did reveal that the greater accumulation of fluorescence occurred in the pollen tube wall if Ca was supplemented to the media than when aureomycin alone was present. The promotive pollen growth the media of Ca alone was further enhanced by the addtion of aureomycin. It was assumed that the promoted pollen growth with aureomycin in the Ca media was probably brought about by a supporting role of aureomycin in the Ca action.