• Biomolecules & Therapeutics
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• v.11 no.3
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• pp.190-195
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• 2003

To assess the genotoxicity of AS6, several classical toxicological tests were performed. In Ames test, AS6 did not show any transformation of revertant with or without S-9 metabolic activating system, indicating the lack of mutagenic effect of the compound. To assess clastogenic effect, in vivo micronucleus and in vitro chromosomal aberration assays were performed using male ICR mice and Chinese hamster lung (CHL) fibroblast cells, respectively. Chromosomal aberration was not induced regardless of the presence of S-9 metabolic activating system. In addition, AS6 did not cause any increase in the incidence of micronucleated polychromatic erythrocytes at any of the dose levels, suggesting little clastogenicity in vitro or in vivo. Taken together, these results demonstrate that AS-6 has no mutagenic effect in our test system.

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.11-15
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• 2004

Embryonic stem (ES) cells are derived from the inner cell mass of the blastocyst-stage embryos that can be propagated indefinitely and, at the same time, can be differentiated into all the cell types that constitute the body. Current research using ES cells is mainly focused on the efficient generation of specific cell types by employing optimal differentiation conditions, which often requires the genetic manipulation of ES cells. As a way of developing an efficient system to regulate foreign gene expression in ES cells, we have inserted the gene encoding Corynebacterium diphtheria toxin-A (DTA) into an autonomously induced plasmid under positive doxycycline control ('Tet-on' system). In this study, we demonstrate that this system can lead to the cell death of mouse ES cells by the induction of DTA expression when exposed to the tetracycline derivative, doxycycline. MTT assay showed that this induction resulted in the apoptosis of ES cells.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4002-4018
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• 2023

An integrated neutron interrogation system has been developed for non-destructive assay of highly-radioactive special nuclear materials, to accumulate knowledge of the method through developing and using it. The system combines a differential die-away (DDA) measurement system for the quantification of nuclear materials and a prompt gamma-ray analysis (PGA) system for the detection of neutron poisons which disturb the DDA measurements; a common D-T neutron generator is used. A special care has been taken for the selection of materials to reduce the background gamma rays produced by the interrogation neutrons. A series of measurements were performed to test the basic performance of the system. The results show that the DDA system can quantify plutonium of as small as 20 mg and it is not affected by intense neutron background up to 1.57 × 10⁷ s^-1 and gamma ray of 4.43 × 10¹⁰ s^-1. The gamma-ray background counting rate at the PGA detector was reduced down to 3.9 × 10³ s^-1 even with the use of the D-T neutron generator. The test measurements show that the PGA system is capable of detecting 0.783 g of boron and about 86.8 g of gadolinium in 30 min.

• Korean Journal of Pharmacognosy
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• v.23 no.4
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• pp.264-267
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• 1992

The cytotoxic activity of medicinal plants was screened using A549 human lung cancer cell line. Plant materials were extracted with 80% methanol and fractionated to chloroform and water layers. Each methanol, chloroform, and water extract of thirty-two medicinal plants was tested for cytotoxic activity in A549 cell culture system and the cell viability was measured by SRB assay.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.160.3-161
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• 2003

Aldehyde and active form of free oxygen produced in alcohol metabolism in liver are the cause of liver cell damage. The main system of alcohol metabolism is composed of alcohol dehydrogenase(ADH), aldehyde dehydrogenase(ALDH) and cytochrome P4502E1. Alcohol dehydrogenase is reversible in alcohol metabolism. To block the backward reaction and enhance alcohol oxidation, acetaldehyde trapping agents were assayed. The assay was carried out by measuring decreasing NADH at 340nm, using acetaldcehyde and NADH as substrate and coenzyme respectively. (omitted)

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.63-63
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• 1996

We performed chromosomal aberration assay in Chinese Hamster Lung (CHL) cells in vitro to evaluate theclastogenicity of 11 synthetic chemicals which were listed in Toxicity Evaluation Program of Ministry of Environment of Republic of Korea in 1996. All of the chemicals were carried out MTT assay to determine the 50% cell growth inhibition concentration. All compounds were tested with and without metabolic activation system. Benzoyl chloride revealed positive result at $43\;\mu\textrm{g}/m{\ell}$ in the presence of metabolic activation system, and at 30.8, 61.5 and $123\;\mu\textrm{g}/m{\ell}$ in the absence of metabolic activation system. And p-phenoxy ethanol was observed as positive with the metabolic activation system, but negative without metabolic activation system. Especially 2-propyn-l-ol showed high frequency of pulverization and showed critical difference of cytotoxicity between with and without S9 mixture. Pulverizatiuon is not included in the frequency of structural aberration in our criteria. Dicyclopentadiene, methacrylic acid, aa-dimethylbenzyl hydroperoxide, benzylbutyl phthalate, and p-chlorophenal were revealed negative results.esults.

• The Journal of Internal Korean Medicine
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• v.30 no.3
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• pp.465-480
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• 2009

Objective : Lonicerae Flos has detoxifying properties and been used as antipyretic, antibacterial and antitumor. Fermentation of herbal medicine is known to increase the absorption, enhance effectiveness, decrease herbal toxicity and reduce side-effects. This study was performed to measure the effects of fermented Lonicerae Flos on influenza A/WSN (H1N1) virus replication. Material and Methods : Lonicerae Flos was fermented by Lactobacillus casei PM1. Fermented Lonicerae Flos was treated for 12 hours to MDCK (Mardin Darby canine kidney) cells, then cell-virulence was observed by MTT assay for 12 hours, 24 hours, and 36 hours after treatment. Following cases were conducted for 0, 10, 100, and $1000{\mu}g/ml$ concentrations of fermented Lonicerae Flos under the same time-frame; the fermented Lonicerae Flos was treated to MDCK cells before and after contamination by A-type influenza virus. The fermented Lonicerae Flos and the virus were mixed directly. The influence was observed by MTT assay and plaque assay. Results : These findings suggest that the fermented Lonicerae Flos inhibited the virulence of influenza A virus in MDCK cells and suppressed the plaque forming colonies induced by influenza A virus. Furthermore, pretreatment with fermented Lonicerae Flos was more effective than post-treatment. The titer of influenza virus was reduced for all before and after influenza A virus inoculation.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.27-31
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• 1985

A rapid assay for interferon based on reduction of cytopathic effect was developed with HEp-2 and Vesicular Stomatitis Virus. The number of manipulations and the lengths of the various incubation steps were reduced to minimum. The assay is simple to perform and can be completed with 22-24 hr. Moreover, it was precise method than CPE-reading method.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.530-533
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• 2002

This paper describes the development of an enzymatic assay system for the identification of specific inhibitors of sortase, a transpeptidase that cleaves surface proteins of Cram-positive bacteria, from Staphylococcus aureus ATCC 6538p for antibacterial drug discovery. The coding region of the enzyme was amplified with the exception of the N-terminal membrane anchor sequence, cloned into a vector providing His-Patch-thioredoxin-tag at the N-terminus, expressed in Escherichia coli, and purified by metal chelate affinity chromatography. The enzyme activity was determined by quantifying increased fluorescence intensity upon cleavage of synthetic Dabcyl-QALPETGEE-Edans peptide. The results suggest that the developed in vitro assay system call be used in the search for sortase inhibitors In a short period of time.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.173-182
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• 2020

Human Astrovirus (HuAstV), known as a waterborne virus, is a group IV positive-sense single-stranded RNA that belongs to Astroviridae. The first outbreak of HuAstV was reported in England in 1975. HuAstV can exist not only among clinical patients but also in various water environments, such as water for agriculture and vegetables. For diagnosis of HuAstV from water samples, a polymerase chain reaction (PCR) system has been developed. However, the PCR-based diagnostic method has problems in field application, such as reaction time, sensitivity and specificity. For this reason, in this study we developed the loop-mediated isothermal amplification assay (LAMP) system, aimed specifically at HuAstV. Three prepared LAMP primer sets were tested by specificity, non-specificity and sensitivity; one LAMP primer set was selected with optimum reaction temperature. The developed LAMP primer set reaction conditions were confirmed at 62℃, and detection sensitivity was 1 fg/μL. In addition, restriction enzyme HaeIII (GG/CC) was introduced to confirm that the LAMP reaction was positive. As a result, selected LAMP primer set was 100 - 1000 times more specific, rapid, and sensitive than conventional-nested PCR methods. For verification of the developed LAMP assay, twenty samples of cDNA from groundwater samples were tested. We expect that the developed LAMP assay will be used to diagnose HuAstV from various samples.