• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.657-663
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• 2011

$Bacillus$ $cereus$ is widely distributed on various foods and is known to cause clinical infections, food poisoning toxin induced diarrhea and vomiting. In this study, $B.$ $cereus$ group detected and analyzed rice, rice bran, and biofilm characterization of $B.$ $cereus$ confirmed. $B.$ $cereus$ was identified in approximately 34.6% of brown rice and 50.0% of rice bran. $B.$ $thuringiensis$ was detected in 3.9% of brown rice and 23% of rice bran, and $B.$ $mycoides$ was isolated from rice bran. The microtiter plate assay detected differences in biofilm-forming ability among $B.$ $cereus$ group isolates. Biofilm of $B.$ $cereus$ seemed to increase the MIC values of antimicrobial agent and antibiotic compounds compared with planktonic cells. Therefore, sufficient attention should be given to good manufacturing practice and good agriculture practice to avoid contamination of $B.$ $cereus$ group raw material including rice.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.370-374
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• 2009

A double-layer optical sensing membrane has been fabricated to measure the concentration of dissolved oxygen (DO) and pH value simultaneously. (tris(4,7-diphenyl-1,10-phenanthroline (Rudpp) ruthenium(II)) as a DO sensitive dye has been mixed in the methyl trimethoxy silane (MTMS) sol-gel solution and coated onto one well in a 24-well microtiter plate. On the DO-sensing layer the GA (3-glycidoxypropyl trimethoxy silane (GPTMS), 3-aminopropyl trimethoxy silane (APTMS)) sol-gel solution mixed with 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) has been coated and used to measure pH values. The double-layer sensing membrane was affected by ionic strength and temperature. The double-layer sensing membrane for DO and pH has been applied to online monitor in microorganism cultivation processes and showed a good performance.

• Biomedical Science Letters
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• v.1 no.1
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• pp.1-8
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• 1995

The present study was undertaken to determine the dissociation constant (Kd)of monoclonal antibody to human apolipoprotein A-I (apo A-I) using enzyme-linked immunosorbent assay (ELISA). First the monoclonal antibody was incubated in solution with the antigen until the equilibrium was reached; then the free antibody which remains unsaturated at equilibrium was captured by binding to antigen on the microtiter plate and be measured by a classical indirect ELISA. The value of Kd determined from Scatchard plot was 0.625$\times$10^{-9}$ for purified antibody and 0.720$\times$10$^{-9}$ for unpurified antibody. This method was valuable for the measurement of true dissociation constant and found to be simple, reproducible, and accurate.

• CELLMED
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• v.4 no.2
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• pp.11.1-11.6
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• 2014

Cinnamomum zeylanicum (C. zeylanicum) is a tropical evergreen tree of Lauraceae family. It is one of the oldest culinary spices known and used traditionally in many cultures for centuries. In addition to its culinary uses, cinnamon also possesses as a folk remedy of many health disease condition including analgesic, antiseptic, antispasmodic, aphrodisiac, astringent, carminative, haemostatic, insecticidal, and parasiticide and memory enhancing property. This study was aimed to assess the acetylcholinesterase and butyrylcholinesterase inhibitory activity of standardized methanol extract of the C. zeylanicum. Gas chromatography - mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) analysis were done to identify the presence of eugenol as chemical component and support the neuroprotective activity in the extract. Anticholinesterase inhibitory activity of crude methanol extract of C. zeylanicum leaves and cinnamon oil were evaluated by 96-well microtiter plate assay and thin layer chromatography bioassay detection methods. This study revealed that cinnamon oil ($IC_{50}:45.88{\pm}1.94{\mu}g/ml$) has better anticholinesterase activity than methanol extract ($IC_{50}:77.78{\pm}0.03{\mu}g/ml$). In HPLC analysis, retention time of eugenol in cinnamon oil was found to be 15.81 min which was comparable with the retention time (15.99 min) of the reference standard, eugenol. Seven chemical compounds were identified by GC-MS analysis, in which eugenol as an important phytoconstituents. Thus the phytochemicals from C. zeylanicum methanol leaves extract could be developed as potential source of anticholinesterase activity, with particular benefit in the symptomatic treatment of Alzheimer's disease.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.905-912
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• 2007

A novel ${\beta}-glucosidase$ gene, bglA, was isolated from uncultured soil bacteria and characterized. Using genomic libraries constructed from soil DNA, a gene encoding a protein that hydrolyzes a fluorogenic analog of cellulose, 4-methylumbelliferyl ${\beta}-D-cellobioside$ (MUC), was isolated using a microtiter plate assay. The gene, bglA, was sequenced using a shotgun approach, and expressed in E. coli. The deduced 55-kDa amino acid sequence for bglA showed a 56% identity with the family 1 glycosyl hydrolase Chloroflexus aurantiacus. BglA included two conserved family 1 glycosyl hydrolase regions. When using $p-nitrophenyl-{\beta}-D-glucoside$ (pNPG) as the substrate, the maximum activity of the purified ${\beta}-glucosidase$ exhibited at pH 6.5 and $55^{\circ}C$, and was enhanced in the presence of $Mn^{2+}$. The $K_m\;and\;V_{max}$ values for the purified enzyme with pNPG were 0.16 mM and $19.10{\mu}mol/min$, respectively. The purified BglA enzyme hydrolyzed both pNPG and $p-nitrophenyl-{\beta}-D-fucoside$. The enzyme also exhibited substantial glycosyl hydrolase activities with natural glycosyl substrates, such as sophorose, cellobiose, cellotriose, cellotetraose, and cellopentaose, yet low hydrolytic activities with gentiobiose, salicin, and arbutin. Moreover, BglA was able to convert the major ginsenoside $Rb_1$ into the pharmaceutically active minor ginsenoside Rd within 24 h.

• Biomedical Science Letters
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• v.5 no.1
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• pp.11-15
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• 1999

Thyroxine (3,5,3',5'-L-tetraiodothyronine; T$_4$) is the most commonly measured thyroid hermono for the diagnosis of various thyroid disorders. Although radioimmunoassay (RIA) is still considered as the reference technique for the measurement of T$_4$, it is generally regarded that RIA has its primary disadventages in handling the wastes and controling the human and material resources. Therefore, establishment of enzyme-linked immunosorbent assay (ELISA) has of great significance. To verify the usefulness of our enzyme immunoassay, we have obtained the standard dose response curve of T$_4$ in patient's sera which is inversely proportional to the amount of herseradish peroxidase (HRP) conjugated monoclonal antibody of T$_4$ bound to the wells. The correlation coefficient (r) between the ELISA and chemiluminescent assay was 0.444 (n=38). Thus we have investigated the establishment of rapid and sensitive competitive ELISA assay method for detection of T$_4$ in patient's sera.

• BMB Reports
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• v.40 no.6
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• pp.936-943
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• 2007

Previously it was reported that promoter of groES-groEL operon of Staphylococcus aureus is induced by various cellwall active antibiotics. In order to exploit the above promoter for identifying novel antistaphylococcal drugs, we have cloned the promoter containing region ($P_g$) of groES-groEL operon of S. aureus Newman and found that the above promoter is induced by sublethal concentrations of many antibiotics including cell-wall active antibiotics. A reporter S. aureus RN4220 strain (designated SAU006) was constructed by inserting the $P_g$-lacZ transcriptional fusion into its chromosome. Agarose-based assay developed with SAU006 shows that $P_g$ in single-copy is also induced distinctly by different classes of antibiotics. Data indicate that ciprofloxacin, rifampicin, ampicillin, and cephalothin are strong inducers, whereas, tetracycline, streptomycin and vancomycin induce the above promoter weakly. Sublethal concentrations of ciprofloxacin and ampicilin even have induced $P_g$ efficiently in microtiter plate grown SAU006. Additional studies show for the first time that above promoter is also induced weakly by arsenate salt and hydrogen peroxide. Taken together, we suggest that our simple and sensitive assay systems with SAU006 could be utilized for screening and detecting not only novel antistaphylococcal compounds but also different toxic chemicals.

• BMB Reports
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• v.34 no.6
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• pp.537-543
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• 2001

In the present study, an in vitro ELISA system to assess the interaction between Src homology (SH)2 domains and phosphotyrosine that contain peptides was established using purified GST-conjugated SH2 proteins and synthetic biotinylated phosphotyrosine that contain oligopeptides. The SH2 domains bound the relevant phosphopeptides that were immobilized in the streptavidin-coated microtiter plate in a highly specific and dose-dependent manner. The epidermal growth factor receptor (EGFR)-, T antigen (T Ag)-, and platelet-derived growth factor receptor (PDGFR)-derived phosphopeptides interacted with the growth factor receptor binding protein (Grb)2/SH2, Lck/SH2, and phosphatidyl inositol 3-kinase (PI3K) p85/SH2, respectively. No cross-reactions were observed. Competitive inhibition experiments showed that a short phosphopeptide of only four amino acids was long enough to determine the binding specificity. Optimal concentrations of the GST-SH2 fusion protein and phosphopeptide in this new ELISA system for screening the binding blockers were chosen at 2nM and 500nM, respectively. When two candidate compounds were tested in our ELISA system, they specifically inhibited the Lck/SH2 and/or p85/SH2 binding to the relevant phosphopeptides. Our results indicate that this ELISA system could be used as an easy screening method for the discovery of specific binding blockers of protein-protein interactions via SH2 domains.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.76-82
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• 1994

A competitive indirect enzyme-linked immunosorbent assay(ELISA) was developed to detect and quantify levels of the fungicide metalaxyl in crops. Antiserum against metalaxyl was demonstrated in rabbits immunized with metalaxyl-human serum albumin(HSA) conjugate. Metalaxyl-protein conjugate was prepared by mixed anhydride and peptide coupling method with EDC. In this assay, metalaxyl-ovalbumin(OA) was $coated(8{\mu}g/ml)$ on the microtiter plate, which was incubated for 1 hr at $4^{\circ}C$ or 4 hr at $37^{\circ}C$ with diluted antiserum(1:2,000). The optimum volume ratio of antigen and antibody mixture was 0.5: 1, which was incubated for 1 hr at $20^{\circ}C$. The detection of metalaxyl bound on the surface of wells was determined by the reaction(30 min) of antirabbit Ig G-peroxidase conjugate with its substrate.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.422-429
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• 2013

The aim of this study was to investigate the characteristics of canine uropathogenic Escherichia coli (UPEC) and the interaction between canine UPEC and human bladder epithelial cells. Ten E. coli isolates collected from dogs with cystitis were analyzed for antimicrobial resistance patterns, the presence of virulence factors, and biofilm formation. The ability of these isolates to induce cytotoxicity, invade human bladder epithelial cells, and stimulate an immune response was also determined. We observed a high rate of antimicrobial resistance among canine UPEC isolates. All virulence genes tested (including adhesins, iron acquisition, and protectin), except toxin genes, were detected among the canine UPEC isolates. We found that all isolates showed varying degrees of biofilm formation (mean, 0.26; range, 0.07 to 0.82), using a microtiter plate assay to evaluate biofilm formation by the isolates. Cytotoxicity to human bladder epithelial cells by the canine UPEC isolates increased in a time-dependent manner, with a 56.9% and 36.1% reduction in cell viability compared with the control at 6 and 9 h of incubation, respectively. We found that most canine UPEC isolates were able to invade human bladder epithelial cells. The interaction between these isolates and human bladder epithelial cells strongly induced the production of proinflammatory cytokines such as IL-6 and IL-8. We demonstrated that canine UPEC isolates can interact with human bladder epithelial cells, although the detailed mechanisms remain unknown. The results suggest that canine UPEC isolates, rather than dogspecific pathogens, have zoonotic potential.