• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.68-73
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• 2012

In this study, a method was developed using molecular biological technique to distinguish an authenticity of meats for processed meat products. The genes for distinction of species about meats targeted at 12S or 16S genes in mitochondrial DNA and the species-specific primers were designed by that PCR products' size was around 200bp for applying to processed products. The target materials were 10 species of livestock products and it checked whether expected PCR products were created or not by electrophoresis after PCR using species-specific primers. The results of PCR for beef, pork, goat meat, mutton, venison, and horse meat were 131, 138, 168, 144, 191, and 142 bp each. The expected PCR products were confirmed at 281, 186, 174, and 238 bp for chicken, duck, turkeymeat, and ostrich. Also, non-specific PCR products were not detected in similar species by species-specific primers. The method using primers developed in this study confirm to be applicable for composite seasoning including beefs and processed meat products including pork and chicken. Therefore, this method may apply to distinguish an authenticity of meats for various processed products.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.701-710
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• 2004

Uncertainty was quantified to evaluate calcium determination result in infant formula with AAS (Atomic Absorption Spectrometry) and ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Uncertainty sources in measurand, such as sample weight, final volume of sample, sample dilution and the instrumental result were identified and used as parameters for combined standard uncertainty based on the GUM (Guide to the expression of uncertainty in measurement) and Draft EURACHEM/CITAC Guide. Uncertainty components of each sources in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, standard material molecular weight, standard solution concentration, standard solution dilution factor, sample dilution factor, calibration curve, recovery, instrumental precision, reproducibility, and stability, Each uncertainty components were evaluated by uncertainty types and included to calculate combined uncertainty. The kinds of uncertainty sources and components in the analytical method by AAS and ICP-AES were same except sample dilution factor for AAS. The analytical results and combined standard uncertainties of calcium content were estimated within the certification range $(367{\pm}20\;mg/100g)$ of CRM (Certified Reference Material) and were not significantly different between method by AAS followed by ashing and method by ICP-AES followed by acid digestion as $359.52{\pm}23.61\;mg/100g\;and\;354.75{\pm}16.16\;mg/100g$, respectively. Identifying uncertainty sources related with precision, repeatability, stability, and maintaining proper instrumental conditions as well as personal proficiency was needed to reduce analytical error.

• Tuberculosis and Respiratory Diseases
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• v.56 no.3
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• pp.261-268
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• 2004

Background : The resurgence of tuberculosis and outbreaks of multidrug resistant (MDR) tuberculosis have increased the emphasis for the development of new susceptibility testing of the Mycobacterium tuberculosis for the effective treatment and control of the disease. Conventional drug susceptibility testings, such as those using egg-based or agar-based media have some limits, such as the time required and difficulties in determining critical inhibitory concentrations, but these are still being used in many diagnostic laboratories because of no better lternatives, considering cost and accuracy. To overcome these limits, a rapid and simple method for new susceptibility testing, using live and dead assays, was applied for a bacterial cell viability assay to distinguish dead from live bacterial cells based on two-color fluorescence. Materials and Methods Strains : Forty strains were used in this study, 20 susceptible to all antituberculosis drugs and the other 20 resistant to the four first line antituberculosis drugs isoniazid, rifampicin, streptomycin and ethambutol. Antibiotics : The four antibiotics were dissolved in 7H9 broth to make the following solutions: $0.1{\mu}g\;isoniazid(INH)/m{\ell}$, $0.4{\mu}g\;rifampicin(RMP)/m{\ell}$, $4.0{\mu}g\;streptomycin(SM)/m{\ell}$ and $4.0{\mu}g\;ethambutol(EMB)/m{\ell}$. Results : Live and dead Mycobacterium tuberculosis cells fluoresced green and red with the acridin (Syto 9) and propidium treatments, respectively. These results are very well accorded with conventional drug susceptibility testing by proportional method on Lowensen-Jensen media (L-J) containing 4 drugs (INH, RMP, EMB and SM), showing a 93.7 % accordance rate in susceptible strains and 95% in resistant strains. Conclusion : The results of the drug susceptibility testing using the live and dead bacterial cell assay showed high accordance rates compared with the conventional proportion method on L-J. This finding suggests that the live and dead bacterial cell assay can be used as an alternative to conventional drug susceptibility testing for M. tuberculosis strains.

• The Korean Journal of Mycology
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• v.26 no.3 s.86
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• pp.373-379
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• 1998

Rhizoctonia solani [Thanatephorus cucumeris (frank) Donk], one of the major soil-borne plant pathogens with world-wide distribution, can cause great damages on various crops. In Korea, sheath blight on rice caused by this pathogen is the major concern, and active studies on this pathogen have been performed. However, most of these studies were concerned with pathogenicity of the isolates instead of molecular analyses of different AGs of R. solani. Therefore, in this study, thirty isolates of Rhizoctonia solani collected from various sources were used for the analyses of genetic relationships among themselves and for the rapid anastomosis grouping with RAPD method. As a result, thirty isolates of known and unknown AGs were grouped into five subgroups and each group included AG-1, AG-2, AG-3, AG-4, and AG-5. RS-1 isolate was found to be closely related to AG-5. Isolates RS-4, RS-14, RS-17, and RS-16 were found to be closely related to AG-2-2(III B). Isolate RS-13 was closely related to AG-4, isolates RS-8 and RS-10 were closely related to AG-1(I B), and isolates RS-7 and RS-21 were closely related to AG-2-2(IV). Isolate RS-19 was closely related to AG-1(I C), and isolates RS-3, RS-5, RS-18, RS-6, and RS-15 were found to be closely related to AG-1.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.25-33
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• 2013

Clenbuterol and ractopamine, which are ${\beta}$-agonists, have been misused as a growth promoting agent in meat producing animals. Clenbuterol was banned for veterinary drug in Korea because of its problems regarding safety. Due to their adverse effects, such as cardiovascular and central nervous diseases on human health proper control and monitoring should be conducted. The existing analytical method of clenbuterol and ractopamine in the Food code was improved through our present study. The bovine muscle samples were subjected to enzymatic hydrolysis, extracted with ethyl acetate and defatted by hexane-methanol partitioning. A molecular imprinted polymer (MIP) solid phase extraction cartridge was used for clean-up and LC-MS/MS was operated in positive multiple reaction monitoring (MRM). Clenbuterol-$d_9$ and ractopamine-$d_3$ were used as an internal standard. The renewed method was validated according to the CODEX guideline. The limits of quantitation for clenbuterol and ractopamine were 0.2 and 0.5 ${\mu}g/kg$, respectively. The mean recoveries ranged in 104.2-113.5% for clenbuterol and in 107.6-118.1% for ractopamine. The improved method was able to save both time and expenses.

• Journal of Life Science
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• v.29 no.6
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• pp.653-661
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• 2019

The first small interfering RNA (siRNA) therapeutics have recently been approved by the Food and Drug Administration in the U.S., and the demand for a new RNA therapeutics bioanalysis method-which is essential for pharmacokinetics, including the absorption, distribution, metabolism, and excretion of siRNA therapeutics-is rapidly increasing. The stem-loop real-time qPCR (RT-qPCR) assay is a useful molecular technique for the identification and quantification of small RNA (e.g., micro RNA and siRNA) and can be applied for the bioanalysis of siRNA therapeutics. When the anti-HPV E6/E7 siRNA therapeutic was used in preclinical trials, the established stem-loop RT-qPCR assay was validated. The limit of detection was sensitive up to 10 fM and the lower limit of quantification up to 100 fM. In fact, the reliability of the established test method was further validated in three intra assays. Here, the correlation coefficient of $R^2$>0.99, the slope of -3.10 ~ -3.40, and the recovery rate within ${\pm}20%$ of the siRNA standard curve confirm its excellent robustness. Finally, the circulation profiles of siRNAs were demonstrated in rat serum, and the pharmacokinetic properties of the anti-HPV E6/E7 siRNA therapeutic were characterized using a stem-loop RT-qPCR assay. Therefore, the stemloop RT-qPCR assay enables accurate, precise, and sensitive siRNA duplex quantification and is suitable for the quantification of small RNA therapeutics using small volumes of biological samples.

• Applied Biological Chemistry
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• v.22 no.4
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• pp.198-209
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• 1979

L-Tyrosine, 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine were synthesized by ${\beta}-tyrosinase$ obtained from cells of Escherichia intermedia A-21, through the reversal of the ${\alpha},{\beta}-elimination$ reaction, and their molecular structures were analyzed by element analysis, NMR spectroscopy, mass spectrometry and IR spectroscopy. Rates of synthesis and hydrolysis of halogenated tyrosines by ${\beta}-tyrosinase$, inhibition of the enzyme activity by halogenated phenols, and effects of addition of m-bromophenol on the synthesis of 2-bromotyrosine were determined. The results obtained were as follows: 1) In the synthesis of halogenated tyrosines, the yield of 2-chlorotyrosine from m-chlorophenol were approximately 15 per cent, that of 2-bromotyrosine from m-bromophenol 13.8 per cent, and that of 2-iodotyrosine from m-iodophenol 9.8 per cent. 2) Rate of synthesis of halogenated tyrosines by ${\beta}-tyrosinase$ was slower than that of tyrosine and the rates were decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius. Relative rate of 2-chlorotyrosine synthesis was determined to be 28.2, that of 2-bromotyrosine to be 8.13, and that of 2-iodotyrosine to be 0.98, respectively, against 100 of tyrosine. However 3-iodotyrosine was not synthesized by the enzyme. 3) The relative rate of 2-chlorotyrosine hydrolysis by ${\beta}-tyrosinase$ was 70.7, that of 2-bromotyrosine was 39.0, and that of 2-iodotyrosine was 12.6 against 100 of tyrosine, respectively. The rate of hydrolysis appeared to be decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius or by decreasing the electronegativity. But 3-iodotyrosine was not hydrolyzed by the enzyme. 4) The activity of ${\beta}-tyrosinase$ was inhibited by phenol markedly. Of the halogenated phenols, o-, or m-chlorophenol and o-bromophenol gave marked inhibition on the enzyme action, however inhibition by iodophenol was not strong. Plotting by Lineweaver-Burk method, a mixed-type inhibition by m-chlorophenol was observed and its Ki value was found to be $5.46{\times}10^{-4}M$. 5) During the synthesizing reaction of 2-bromotyrosine by the enzyme, sequential addition of substrate which was m-bromophenol with time intervals and in a small amount resulted in better yield of the product. 6) The halogenated tyrosines which were produced by ${\beta}-tyrosinase$ from pyruvate, ammonia and m-halogenated phenols were analysed to determine their molecular structures by element analysis, NMR spectroscopy, mass spectrometry, and IR spectroscopy. The result indicated that they were 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.102-107
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• 2009

In clinical pediatric dentistry, we have many chances to encounter the white spot like incipient enamel lesions on the mesial surfaces of the 1st molars with direct vision, especially just after the 2nd primary molars were exfoliated. But it was thought highly desirable to assess if these lesions are properly and effectively managed yet. This study aims at surveying the prevalence of incipient lesions on the mesial surfaces of the 1st molars in children through direct observation and examining the suitability of adhesive sealing on them as a pilot trial in searching for their proper management. 1. Among the 124 mesial surfaces of the 1st molars examined, 34% were sound, 53% had incipient carious lesions and 13% had cavitated lesions. 2. In the sectional views of the specimens, 20% showed microleakage after thermo-cycling and it was thought not recommendable as a permanent method. Therefore in order to effectively fight against the incipient caries lesions in children‘s permanent teeth, it was thought proper not to rely on any one method, but to perform reinforcing oral hygiene and promotion of remineralization in combination with therapeutic sealing which is stronger in short-term sealing effect. Although therapeutic sealing has been considered as the core in minimally invasive concept to treat the white spot lesions, its long-term clinical trials have not been suggested. Continuous research is strongly required for making this approach to acquire permanent nature, especially in regards of proper pretreatment and high molecular materials deeply penetrable into enamel.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.182-187
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• 2012

In this study, the experimental method has been investigated using molecular biological way to identify raw materials from seasoned red-pepper sauce which is one of the most popular spices in Korea. 6 kinds of seasoned red-pepper sauces were chosen as a sample containing chilli pepper, garlic, onion as a major ingredient and species specific primers were used for the identification of the raw material of processed food. Selected samples were pre-treated to remove salt (samples were washed with distilled water 3~4 times for desalting), after that, to amplify the extracted genes, whole genome amplification (WGA) kit was performed. Afterwards, PCR products were confirmed through the electrophoresis. As a result, 102, 180, 280 bp of specific PCR products were confirmed for each major ingredients such as chilli pepper, garlic, onion. From this study, the gene extraction method was validated for the identification of ingredients from the spices and it would be applied to distinction of low quality chilli pepper powder including seasoned red-pepper sauce illegally.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.146-151
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• 2012

In this study, effective gene extraction methods were compared to identify raw materials of processed meat products through molecular biological methods. Species specific primers were used to identify ingredients of processed foods and, as a sample, 13 kinds of processed meat products including beef, pork and chicken. According to the type of sample, 13 kinds of samples were classified into liquid type, source type and powder type. The samples were pre-treated (centrifugation) and (or) performed Whole Gene Amplification (WGA) kit for amplification of the extracted DNA. As a result, it was possible to identify the raw material of products through the centrifugation of sample 1 ml for liquid type of processed meat products. For source type of products after gene extraction, it was required to perform WGA for the identification of ingredients. For powder type products did not required any further pre-treatment and WGA. In this study, it was an opportunity to confirm the possibility of identification of raw material from the gene extraction of processed meat products and this method could be used to examine the authenticity of raw material of products.