• Toxicological Research
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• v.18 no.1
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• pp.99-106
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• 2002

The United States Environmental Protection Agency (EPA) characterized the cancer hazard of di(2-ethylhexyl)-phthalate (DEHP) as a B2 group (probable human carcinogen) and proposed "Guide-lines for Carcinogen Risk Assessment". This guidelines proposed alternative methods for analyzing carcinogen dose-response data and for extrapolating the effects of observed at high dose to predict that might occur at lower doses relevant to human exposure. This proposed guidelines state that "If in a particular case, the evidence indicated a threshold, as in the case of carcinogenicity being secondary to another toxicity that has a threshold, the margin of exposure analysis for toxicity is the same as is done for a non-cancer endpoint". DEHP is excellent candidate for reconideration under the new guidelines for carcinogen risk assessment (John Doull et al., 1998). This study is conducted about risk assessment for infant exposure on DEHP in powdered milk wing methodology in EPA's new guideline on carcinogenic risk assessment. Estimated cancer risk of DEHP in powdered milk and cow milk is 2.83$\times$$10^5$ (using cancer potency: 1.4$\times$$10^2$/ (mg/kg/day)) as mean and MOE is 12075 (using selected NOEL 20 mg/kg/day) as mean. mg/kg/day) as mean.

• Korean Journal of Environment and Ecology
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• v.7 no.1
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• pp.6-9
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• 1993

To examine aluminum toxicity on woody plants, Forsythia koreans and Platanus occidentalis cuttings were grown in the pot(48$\times$33$\times$9cm) filled with sand, and treated aluminum solution and ground water (pH 6.75) 3times per week from April 28, 1993 to June 16. Aluminum solution were prepared 1.0, 2.5 and 5.0mM aluminum potassium sulfate, dilulted with ground water. Growth-related characters (Shoot growth, leaf number and leaf chlorophyll content ) and root growth were measured and compared among the treatments. In all growth-related characters(Shoot growth, leaf number and leaf chlorophyll content), differences among the treatments were highly significant. In root growth, differences among the treatments were highly significant for Forsythia koreana cuttings, but not for Platanus occidentalis cuttings.

• Molecular & Cellular Toxicology
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• v.3 no.3
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• pp.165-171
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• 2007

Mitomycin C (MMC), an antitumor antibiotic isolated from Streptomyces caespitosus, is used in chemotherapy of gastric, bladder and colorectal cancer. MMC is activated in vivo to alkylate and crosslink DNA, via G-G interstrand bonds, thereby inhibiting DNA synthesis and transcription. This study investigates gene expression changes in response to MMC treatment in order to elucidate the mechanisms of MMC-induced toxicity. MMC was admistered with single dose (0.32 and 1.6 ${\mu}M$) to TK6 cells. Applied Biosystem's DNA chips were used for identifying the gene expression profile by MMC-induced toxicity. We identified up- or down-regulated 90 genes including cyclin M2, cyclin-dependent kinase inhibitor 1A (p21, cip1), programmed cell death 1, tumor necrosis factor (ligand) superfamily, member 9, et al. The regulated genes by MMC associated with the biological pathways apoptosis signaling pathway. Further characterization of these candidate markers related to the toxicity will be useful to understand the detailed mechanism of action of MMC.

• The Korean Journal of Food And Nutrition
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• v.24 no.1
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• pp.28-36
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• 2011

To investigate the protective effect of omija(Schizandra chinensis Baillon) tea extracts against the aluminum toxicity, Sprague-Dawley rats($100{\pm}10\;g$) were divided into 6 groups consisting of a control group, a 3% Schizandra chinensis Baillon tea plus extract group, a 1,000 and 2,000 ppm aluminum group, and a 1,000 and 2,000 ppm aluminum plus 3% Schizandra chinensis Baillon tea plus extract group. The rats administered aluminum were given 1,000 and 2,000 ppm of $Al_2(SO_4)_3$ dissolved in distilled water. The aluminum content in tissues from rats administered aluminum was lower than in the tissues of rats of administered aluminum plus 3% Schizandra chinensis Baillon tea in the water extract. Aspartate aminotransferase (AST) and alanine aminotransferase(ALT) levels were increased in the aluminum group and lower in the group receiving a 3% extract of Schizandra chinensis Baillon tea. Lactate dehydrogenase(LDHase) was lower in the group receiving a 3% extract of Schizandra chinensis Baillon tea plus aluminum than in the aluminum group. Cholinesterase(ChEase) was higher in the 3% Schizandra chinensis Baillon tea-aluminum group than in the aluminum group. Plasma levels of renin were increased in the aluminum group, compared to the group receiving 3% Schizandra chinensis Baillon tea plus aluminum. Plasma levels of aldosterone were increased in the aluminum group compared with the 3% Schizandra chinensis Baillon tea plus aluminum group. These results suggest that the group receiving Schizandra chinensis Baillon tea in water extract had a lowered level of aluminum accumulation, and it is believed that the Schizandra chinensis Baillon tea plus water had some protective effects against aluminum toxicity when administered in rats, but the mechanism of these effects remains obscure.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.429-437
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• 2018

In this study, the mixed toxicity of heavy metals (Cu, Pb, Hg) and surfactants (SLS, ALS) was evaluated by using Vibrio fischeri and Daphnia magna. The sensitivity of ecotoxicity to heavy metals was sensitive to daphnia but the case of surfactants were more sensitive to Vibrio fischeri. Experimental results of Vibrio fischeri show that the toxicity value P(O) was lower than the predicted value P(E), and the antagonistic effect was observed when the heavy metal and the surfactant were mixed. It seems that SLS and ALS, which are anionic surfactants, have anionic form on the hydrophilic head, so that they have an antagonistic effect that they are bonded with heavy metal ion which is a cation type and the actual toxicity is lowered. In Daphnia magna, the results showed that antagonistic, additive and synergistic effects were in order as concentrations increased. As the concentration increases, Daphnia magna, which is highly sensitive to heavy metals, seems to have a synergistic effect with a rapid increase in mortality.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.97-104
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• 2004

A new Ti-10Ta-10Nb alloy has designed and examined some possibility of forming more passive oxide film by oxidation treatment which is closely related to corrosion resistance and biocompatibility. Ti-6Al-4V and Ti-10Ta-10Nb alloys were prepared by consumable vacuum arc melting and homogenized at 1050$^{\circ}C$ for 24hours. Alloy specimens were oxidized at the temperature range of 400 to 750$^{\circ}C$ for 30minutes, and the oxide films on Ti alloys were analysed by optical microscope, SEM, XPS and TGA. Cytotoxicity test was performed in MTT assay treated L929 fibroblast cell culture by indirect method. It is found out that the oxide film on Ti-10Ta-10Nb alloy is denser and thinner compared to Ti-6Al-4V alloy. The weight gain during the oxidation was increased rapidly at the temperature above 650$^{\circ}C$ for Ti-6Al-4V alloy and above 700$^{\circ}C$ for Ti-10Ta-10Nb alloy respectively. It was analysed that the passive film of the Ti alloys consisted of TiO2 through X-ray photoelectron spectroscopy (XPS) analysis. It is found out by cytotoxicity test that moderate oxidation treatment lowers cell toxicity, and Ti-10Ta-10Nb alloy showed better result compared to Ti-6Al-4V alloy.

• Economic and Environmental Geology
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• v.35 no.2
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• pp.103-112
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• 2002

Despite the ecological importance of potentially phytotoxic $Al_{13}$-tridecamer and its formation in the simulated condition, it was not recognized in the natural soil environment. Here we performed thermodynamic calculations to examine the stability condition of $Al_{13}$-tridecamer based on the solubility of AI in the Bo horizon of Andisols, Jeju Island, dominantly composed of AI-containing solid phases such as $Al(OH)_{3}$, proto-imogolite and/or imogolite. We have found that $Al(OH)_{3}$, proto-imogolite and/or imogolite may control Al solubility in the moderate acid condition. It means that AI total activity of the soil solution equilibrated with these solid phases ranges from $10^{-6}$ ~ $10^{-8}$M in the pH 5 to 7. Calculations based on the thermodynamic data strongly indicate that the formation of $Al_{13}$-tridecamer closely related to the total activity of AI in the system. For example, for the formation of $Al_{13}$-tridecamer of $10^{-5}$M, Al total activity of $3{\times}10^{-3}$M are needed at pH 4, and $2{\times}10^{-5}$M in the pH 5 to 7. Therefore, this research and the thermodynamic consideration suggest strongly that $Al_{13}$-tridecamer should be negligible in natural soils, especially Andisols and Spodosols, These mainly contain $Al(OH)_{3}$, proto-imogolite and/or imogolite, which could prevent the formation of $Al_{13}$-tridecamer by controlling the AI total activity low. It means that the toxicity of $Al_{13}$-tridecamer with the increase of soil acidification may be considered to be definitely low.

• The Korean Journal of Applied Statistics
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• v.27 no.7
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• pp.1115-1123
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• 2014

The main purpose of phase I clinical trials is to estimate the Maximum Tolerated Dose (MTD), which minimizes side effect and assures safety of a new drug by evaluating the toxicity at each dose-level. The conventional MTD estimation methods is Standard method (Storer, 1989; Korn et al., 1994), Accelerated Titration Designs (Simon et al., 1997) and DM method (Dixon and Mood, 1948) etc. In this paper, MTD estimation method with de-escalation is suggested phase I clinical trials. The proposed MTD estimation method is compared to Accelerated Titration Designs, SM3 without de-escalation method and SM3 with de-escalation method using a Monte Carlo simulation.

• The Korea Journal of Herbology
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• v.36 no.5
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• pp.15-27
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• 2021

Objectives : The processing of Pinelliae Tuber and Arisaematis Rhizoma is a crucial step to reduce the severe acrid irritation mainly due to the needle-like crystals (raphides). Ginger, alum and bile juice have been used as adjuvant materials for the processing. Methods : Bibliographic research on ancient processing and experimental processing was performed to investigate the toxicity reduction mechanisms of the processing with ginger, alum and bile juice. Results : Ginger has been a major adjuvant for the processing of Pinelliae Tuber, followed by alum and bile juice since Song (宋) and Myeong (明) dynasties, and Arisaematis Rhizoma has been mainly used as Damnamseong (膽南星). The raphides consisting of calcium oxalate, lectin, agglutinin and polysaccharides can induce acrid irritation and the inflammatory reactions. The lipophilic components in the ginger denatured the structure of raphides and 6-gingerol-contained ginger extract attenuated the inflammatory reaction. The calcium ion (Ca²⁺) of calcium oxalate was substituted to the aluminium ion (Al³⁺) of the alum, which damaged the calcium oxalate structure. Lectin attached to the surface of raphides was dissolved in alum solution and consequently its structure was denatured. The cholate in the bile juice formed the complex with the oxalate anion or the calcium cation. Moreover, the enzymes activated by Lactobacillus or Bifidobacterium during the fermentation promoted the fragmentation of oxalate. Conclusion : The adjuvant materials damaged the raphides by denaturing or degrading the calcium oxalate, resulting in the reduction of acrid irritation. Further experimental studies would support the toxicity reduction mechanism of the processing.

• Korean Journal of Metals and Materials
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• v.47 no.8
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• pp.508-515
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• 2009

Ti-6Al-4V biomaterial is widely used as a bone alternative. However, Ti-6Al-4V ELI alloy suffers from numerous problems such as a high elastic modulus and high toxicity. Therefore, non-toxic biomaterials with low elastic moduli need to be developed. Ti-HA(hydroxyapatite) composites were fabricated in the present work by pulsed current activated sintering (PCAS) at $1000^{\circ}C$ under 60 MPa using mixed Ti and HA powders. The effects of HA content on the physical and mechanical properties of the sintered Ti-HA composites have been investigated. X-ray diffraction(XRD) analysis of the Ti-HA composites, including Ti-40 wt%HA in particular, revealed new phases, $Ti_{2}O$, CaO, $CaTiO_3$, and TixPy, formed by chemical reactions between Ti and HA during sintering. The hardness of the Ti-HA composites decreased with an increase in HA content. The corrosion resistance of these composites was observed to be an excellent candidate as a commercial Ti-6Al-4 V ELI alloy. A Ti-5 wt%HA composite fabricated by PCAS is recommended as a new biomaterial, because it offers good corrosion resistance, compressive strength, wear resistance, and biocompatibility, and a low Young's modulus.