• The Korean Journal of Physiology and Pharmacology
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• v.2 no.2
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• pp.209-216
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• 1998

The present study was designed: (1) to determine whether or not hypoxia stimulates the release of endothelium-derived relaxing factors (EDRFs) from endothelial cells, and (2) to examine whether or not the hypoxia-induced EDRFs release is further augmented by previous hypoxia-reoxygenation, using bioassay system. In the bioassay experiment, rabbit aorta with endothelium was used as EDRFs donor vessel and rabbit carotid artery without endothelium as a bioassay test ring. The test ring was contracted by prostaglandin $F_{2{\alpha}}$ $(3{\times}10^{-6}\;M/L)$, which was added to the solution perfusing through the aortic segment. Hypoxia was evoked by switching the solution aerated with 95% $O_2/5%\;CO_2$ mixed gas to one aerated with 95% $N_2/5%\;CO_2$ mixed gas. When the contraction induced by prostaglandin $F_{2{\alpha}}$ reached a steady state, the solution was exchanged for hypoxic one. And then, hypoxia and reoxygenation were interchanged at intervals of 2 minutes (intermittent hypoxia). The endothelial cells were also exposed to single 10-minute hypoxia (continuous hypoxia). When the bioassay ring was superfused with the perfusate through intact aorta, hypoxia relaxed the precontracted bioassay test ring markedly. Whereas, when bioassay ring was superfused with the perfusate through denuded aorta or polyethylene tubing, hypoxia relaxed the precontracted ring slightly. The relaxation was not inhibited by indomethacin but by nitro-L-arginine or methylene blue. The hypoxia-induced relaxation was further augmented by previous hypoxia-reoxygenation and the magnitude of the relaxation by intermittent hypoxia was significantly greater than that of the relaxation by continuous hypoxia. The results suggest that hypoxia stimulates EDNO release from endothelial cells and that the hypoxia-induced EDNO release is further augmented by previous hypoxia-reoxygenation.

• Proceedings of the Korean Society of Crop Science Conference
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• 1989.02a
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• pp.58-59
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• 1989

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.459-468
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• 2022

Long-term data analyses and bioassay experiments were conducted to assess limiting nutrients in Cheonsu Bay and Taean sea. First, long-term nutrient data (2004-2016) provided by the National Water Quality Monitoring Network were used to assess potential limiting nutrients. Analysis of the long-term data showed that the dissolved inorganic nitrogen/dissolved inorganic phosphate (DIN/DIP) ratio was mostly below 16, with N limitation being dominant. A subsequent analysis using the concentration ratios of N, P, and Si showed that N limitation was dominant during summer and autumn but that Si limitation occasionally occurred during winter and spring in relatively limited areas. However, the dominant limiting nutrient was not determined. The nutrient analysis of the field water collected during the bioassay experiment showed that DIN/DIP revealed P limitation at all stations in March and May, whereas N limitation was dominant in July and October. In the analysis using the concentration ratios of N, P, and Si, P and Si limitation appeared in March and May, but there were points with no dominant limiting nutrient. However, N limitation was dominant in July and October. In the bioassay experiment for assessment of the actual limiting nutrient, the results showed no specific limiting nutrient in March, whereas NH₄⁺ and NO₃^- showed responses in May, July, and October, which confirmed that N was a substantial limiting nutrient directly involved in phytoplankton growth during this period.

• The Korean Journal of Nuclear Medicine
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• v.9 no.2
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• pp.39-46
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• 1975

It is the purpose of this paper to design the most preferable method of erythropoietin bioassay in Korea. Bioassay utilizing polycythemic mice are currently in general use for the indirect determination of erythropoietin. Assay animals are usually prepared either by transfusion or by exposure to reduced oxygen tension in specially constructed chamber. We prepared the polycythemic, mice by the specially constructed hypobaric chamber. We observed weights and hematocrits of the mice in the hypobaric chamber, then hematocrits and 72 hours $^{59}Fe$ red cell upatke ratio of the polycythemic mice induced by hypoxia after removal from the hypobaric chamber. We designed the method of erythropoietin bioassay according to the results obtained by above experiments. Then we measured the 72 hours $^{59}Fe$ red cell uptake ratio of the polycythemic mice with normal saline, normal plasma and anemic plasma according to the method we designed. The results are followed: 1. The hematocrits of the mice in hypobaric chamber increased to 74% in 14 days It is preferable to maintain the pressure of the chamber to 400mmHg for first 4 days then 300mmHg for last 10 days to reduce the death rate and time consuming in hypobaric chamber. 2. After removal from the hypobaric chamber, the 72 hours $^{59}Fe$ red cell uptake ratio decreased rapidly and maintained the lowest level from the fourth day to tenth day. 3. We design the method of erythropoietin bioassay according to the results of above experiment and to the half life of erythropoietin. 4. The Korean product S9Fe is mixture of $^{59}Fe\;and\;^{55}Fe$. And the $^{59}Fe$ red cell uptake ratio in normal mice was far less with Korean product $^{59}Fe$ than with pure $^{59}Fe$ of foreign product. So it is desirable to use pure $^{59}Fe$ in this method of erythropoietin bioassay. 5. Considering the cost, the technique, the time consuming and the sensitivity it is the most preferable method of erythropoietin bioassay in Korea using hypobaric chamber to induce the polycythemia.

• The Korean Journal of Ecology
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• v.16 no.2
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• pp.181-190
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• 1993

To elucidate phytotoxic effects on the growth of receptor plant, germination and growth experiment of selected species have been performed with aqueous extracts and volatile substances of leaf and of donor plant, Thuja orientalis. The extracts of T. inversely proportional to the concentration. Gas chromatography method was employed for analysis and indentification of phytotoxic substances from T. orientalis. Forty-two kinds of KDICicals including ${\alpha}-thujone$ were identified from T. orientalis essential oil. Bioassay was performed with 6 KDICical such as ${\alpha}-pinene, \;{\alpha}-terpinene, \;{\gamma}-terpinene, \; {\beta}-myrcene$, and among them bornyl acetate was the strongest growth inhibitor.

• Toxicological Research
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• v.4 no.2
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• pp.159-179
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• 1988

This study was carried out to investigate the inhibitory effects of red ginseng extract on preneoplastic nodule formation in the rat liver using a rapid bioassay of hepatocarcinogenesis. Wistar male rats in test groups were fed diets containing 3.0, 0.3 or 003% of red genseng extract for 6 weeks after 2 week of dosing with diethylnitrosamine (DEAN, 200 mg/kg B.W., I.P.) or saline solution. The rats in the control groups were treated with DENA or saline alone. Three weeks after the beginning of the experiment, the two-thirds partial hepatectomy was performed on all animals. The inhibitory effects were investigated by measuring the number, total area and size of hyperplastic nodules enhanced by the 2/3 partial hepatectomy following induction with DENA. The results obtained were summarized as follows: 1. In general, the body weight gains of the rats fed diets containing red ginseng extract were higher than those of other groups.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.256-260
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• 1999

Minimun-detectable levels to 28 antibacterial agents used for the prevention and the treatment of fish diseases were determined to establish optimal detective method of bioassay in fish by the EEC 4-plate method, the modified method of EEC 4-plate and the standard method of analysis in food safety regulation. The test organisms used in the methods of bioassay were as follows: Bacillus subtilis BGA (B. subtilis) and Micrococcus luteus ATCC 9341 (M. luteus) in the EEC 4-plate method, B. subtilis, M. luteus and Bacillus cereus var. mycoides ATCC 11778 (B. cereus) in the modified of EEC 4-plate, and B. subtilis, M. luteus, B. cereus and Bacillus stearothermophilis var. calidolactis C-953 (B. stearothermophilis) in the standard method. The standard method showed predominant sensitivity in the detection of penicillins (PCs), and was also highly sensitive to aminoglycosides (AGs). The sensitivity of standard method in the detection of tetracyclines (TCs), marrolides (MLs), nitrofuran derivatives(NFs) and quinolones (QNs) was very low, and against sulfonamides (SAs), however, was extremely low. The modified method of EEC 4-plate showed very high sensitivity to TCs. Both the EEC 4-plate and the modified method of EEC 4-plate showed competitively high sensitivity in the detection of PCs, MLs, NFs, QNs and SAs. All the methods studied in the experiment showed very low sensitivity against chloramphenicol (CMs). Consequently, the modified method of EEC 4-Plate was the best bioassay method with a wide range of sensitivity for the optimal detection of the residual antibacterial agents in fish.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.1
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• pp.58-64
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• 1990

This study was conducted to investigate the interaction effect of a new plant growth regulator brassinolide and auxins using several bioassay methods such as rice lamina inclination test, oat coleoptile segment growth test and radish hypocotyl elongation test. For rice lamina inclination test, the antagonistic response showed at low concentration combinations of homobrassinolide and auxins (IAA and 2,4-D), while the combinations of high concentration responsed mostly synergistic or additive effects, IAA was generally higher than 2,4-D for combination effect with homobrassinolide. For oat coleoptile segment growth test, the synergistic effect showed at IAA concentrations less than 0.1ppm while additive response exhibited above 0.3ppm regardless of homobrassinolide concentrations. In radish hypocotyl elongation test, the interaction response varied with cotyledon. The sections removed cotyledon showed mostly antagonistic effects, except for combination of homobrassinolide with IAA 3ppm. Interaction responses were Quite different from bioassay methods, particularly using experimental materials: antagonistic responses were usually shown at the section that attached growing point while these for sections that removed growing point were responded synergistic or additive effect due to unstable endogenous hormones.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.743-752
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• 2002

The estimation of the response curve is the important problem in the quantal bioassay. When we estimate the response curve, we determine the design points in advance of the experiment. Then naturally we have a question of which design would be optimal. As a response curve estimator, locally weighted quasi-likelihood estimator has several more appealing features than the traditional nonparametric estimators. The optimal design density for the locally weighted quasi-likelihood estimator is derived and its ability both in theoretical and in empirical point of view are investigated.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.412-421
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• 2008

Nutrient limitation was examined for the Dongbak Lake based on bioassay experiments and analyses of long-term monitoring data. From the results of data analyses, molar ratios of TN/TP and DIN/DIP were higher than 16 : 1 suggesting that phytoplankton growth was potentially limited by phosphorus. Phytoplankton responded to the addition of phosphates in the incubation experiments for all seasons whereas phytoplankton did not respond to other nutrients such as ammonia, nitrate and silicates. Size fraction (net and nano size) of phytoplankton also responded to the addition of phosphorus indicating that phytoplankton growth was limited by phosphorus in the Dongbok Lake. There was also a taxonomic shift from euglenophyceae to bacillariophyceae after addition of phosphate during warm season especially.