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A Study on Preparation of 3'-$[^{18}F]$Fluoro-3'-deoxythymidine and Its Biodistribution in 9L Glioma Bearing Rats (3'-$[^{18}F]$Fluoro-3'-deoxythymidine의 합성과 9L glioma 세포를 이식한 래트에서의 체내동태에 관한 연구)

  • Shim, Ah-Young;Moon, Byung-Seok;Lee, Tae-Sup;Lee, Kyo-Chul;An, Gwang-Il;Yang, Seung-Dae;Yu, Kook-Hyun;Cheon, Gi-Jeong;Choi, Chang-Woon;Lim, Sang-Moo;Chun, Kwon-Soo
    • Nuclear Medicine and Molecular Imaging
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    • v.40 no.5
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    • pp.263-270
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    • 2006
  • Purpose: Several radioisotope-labeled thymidine derivatives such as $[^{11}C]$thymidine was developed to demonstrate cell proliferation in tumor. But it is difficult to track metabolism with $[^{11}C]$thymidine due to rapid in vivo degradation and its short physical half-life. 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) was reported to have the longer half life of fluorine-18 and the lack of metabolic degradation in vivo. Here, we described the synthesis of the 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) and compared with $([^{18}F]FET)\;and\;([^{18}F]FDG)$ in cultured 9L cell and obtained the biodistribution and PET image in 9L tumor hearing rats. Material and Methods: For the synthesis of $[^{18}F]$FLT, 3-N-tert-butoxycarbonyl-(5'-O-(4,4'-dimet hoxytriphenylmethyl)-2'-deoxy-3'-O-(4-nitrobenzenesulfonyl)-${\beta}$-D-threopentofuranosyl)thymine was used as a FLT precursor, on which the tert-butyloxycarbonyl group was introduced to protect N3-position and nitrobenzenesulfonyl group. Radiolabeling of nosyl substitued precursor with $^{18}F$ was performed in acetonitrile at $120^{\circ}C$ and deproteced with 0.5 N HCI. The cell uptake was measured in cultured 9L glioma cell. The biodistribution was evaluated in 9L tumor bearing rats after intravenous injection at 10 min, 30 min, 60 min and 120 min and obtained PET image 60 minutes after injection. Results: The radiochemical yield was about 20-30% and radiochemical purity was more than 95% after HPLC purification. Cellular uptake of $[^{18}F]$FLT was increased as time elapsed. At 120 min post-injection, the ratios of tumor/blood, tumor/muscle and tumor/brain were $1.61{\pm}0.34,\;1.70{\pm}0.30\;and\;9.33{\pm}2.22$, respectively. The 9L tumor was well visualized at 60 min post injection in PET image. Conclusion: The uptake of $[^{18}F]$FLT in tumor was higher than in normal brain and PET image of $[^{18}F]$FLT was acceptable. These results suggest the possibility of $[^{18}F]$FLT at an imaging agent for brain tumor.

Expression of Phospholipase C Isozymes in Human Lung Cancer Tissues (인체 폐암조직에서 Phospholipase C 동위효소의 발현양상)

  • Hwang, Sung-Chul;Mah, Kyung-Ae;Choi, So-Yeon;Oh, Yoon-Jung;Choi, Young-In;Kim, Deog-Ki;Lee, Hyung-Noh;Choi, Young-Hwa;Park, Kwang-Ju;Lee, Yi-Hyeong;Lee, Kyi-Beom;Ha, Mahn-Joon;Bae, Yoon-Su
    • Tuberculosis and Respiratory Diseases
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    • v.49 no.3
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    • pp.310-322
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    • 2000
  • Background : Phospholipase C(PLC) plays an important role in cellular signal transduction and is thought to be critical in cellular growth, differentiation and transformation of certain malignancies. Two second messengers produced from the enzymatic action of PLC are diacylglycerol (DAG) and inositol 1, 4, 5-trisphosphate (IP3). These two second messengers are important in down stream signal activation of protein kinase C and intracellular calcium elevation. In addition, functional domains of the PLC isozymes, such as Src homology 2 (SH2) domain, Src homology 3 (SH3) domain, and pleckstrin homology (PH) domain play crucial roles in protein translocation, lipid membrane modificailon and intracellular memrane trafficking which occur during various mitogenic processes. We have previously reported the presence of PLC-${\gamma}1$, ${\gamma}2$, ${\beta}1$, ${\beta}3$, and ${\delta}1$ isozymes in normal human lung tissue and tyrosine-kinase-independent activation of phospholipase C-${\gamma}$ isozymes by tau protein and AHNAK. We had also found that the expression of AHNAK protein was markedly increased in various mstologic types of lung can∞r tissues as compared to the normallungs. However, the report concerning expression of various PLC isozymes in lung canærs and other lung diseases is lacking. Therefore, in this study we examined the expression of PLC isozymes in the paired surgical specimens taken from lung cancer patients. Methods : Surgically resected lung cancer tissue samples taken from thirty seven patients and their paired normal control lungs from the same patients, The expression of various PLC isozymes were studied. Western blot analysis of the tissue extracts for the PLC isozymes and immunohistochemistry was performed on typical samples for localization of the isozyme. Results : In 16 of 18 squamous cell carcinomas, the expression of PLC-${\gamma}1$ was increased. PLC-${\gamma}1$ was also found to be increased in all of 15 adenocarcinoma patients. In most of the non-small cell lung cancer tissues we had examined, expression of PLC-${\delta}1$ was decreased. However, the expression of PLC-${\delta}1$ was markedly increased in 3 adenocarcinomas and 3 squamous carcinomas. Although the numbers were small, in all 4 cases of small cell lung cancer tissues, the expression of PLC-${\delta}1$ was nearly absent. Conclusion : We found increased expression of PLC-${\gamma}1$ isozyme in lung cancer tissues. Results of this study, taken together with our earlier findings of AHNAK protein-a putative PLD-${\gamma}$, activator-over-expression, and the changes observed in PLC-${\delta}1$ in primary human lung cancers may provide a possible insight into the derranged calcium-inositol signaling pathways leading to the lung malignancies.

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Research and Development Trends on Omega-3 Fatty Acid Fortified Foodstuffs (오메가 3계 지방산 강화 식품류의 연구개발 동향)

  • 이희애;유익종;이복희
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.26 no.1
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    • pp.161-174
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    • 1997
  • Omega-3 fatty acids have been major research interests in medical and nutritional science relating to life sciences since after the epidemiologic data on Green3and Eskimos reported by several researchers clearly showed fewer per capita deaths from heart diseases and a lower incidence of adult diseases. Linolenic acid(LNA) is an essential fatty acid for human beings as well as linoleic acid(LA) due to the fact that vertebrates lack an enzyme required to incorporate a double bond beyond carbon 9 in the chain. In addition the ratio of omega-6 and 3 fatty acids seems to be important in terms of alleviation of heart diseases since LA and LNA competes for the metabolic pathways of eicosanoids synthesis. High consumption of omega-3 fatty acids in seafoods may control heart diseases by reducing blood cholesterol, triglyceride, VLDL, LDL and increasing HDL and by inhibiting plaque development through the formation of antiaggregatory substances like PGI$_2$, PGI$_3$ and TXA$_3$ metabolized from LNA. Omega 3 fatty acids also play an important role in neuronal developments and visual functioning, in turn influence learning behaviors. Current dietary sources of omega-3 fatty acids are limited mostly to seafoods, leafy vegetables, marine and some seed oils and the most appropriate way to provide omega-3 fatty acids is as a part of the normal dietary regimen. The efforts to enhance the intake of omega-3 fatty acids due to several beneficial effects have been made nowadays by way of food processing technology. Two different ways can be applied: one is add Purified and concentrated omega-3 fatty acids into foods and the other is to produce foods with high amounts of omega-3 fatty acids by raising animals with specially formulated feed best for the transfer of omega-3 fatty acids. Recently, items of manufactured and marketed omega-3 fatty acids fortified foodstuffs are pork, milk, cheese, egg, formula milk and ham. In domestic food market, many of them are distributed already, but problem is that nutritional informations on the amounts of omega-3 fatty acids are not presented on the labeling, which might cause distrust of consumers on those products, result in lower sales volumes. It would be very much wise if we consume natural products, result in lower sales volumes. It would be very much wise if we consume natural products high in omega-3 fatty acids to Promote health related to many types of adult diseases rather than processed foods fortified with omega-3 fatty acids.

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Studies on the Organo-mercury Residues in Rice Grain -I. Mercury residues in rice seeds treated with organo-mercury fungicide- (수도(水稻)에 처리(處理)된 유기수은제(有機水銀劑)의 잔류성(殘留性)에 관(關)한 연구(硏究) -제1보(第1報) 침지용유기수은제(浸漬用有機水銀劑)로 처리(處理)된 수도종자중(水稻種子中)의 수은잔류량(水銀殘留量)에 관(關)하여-)

  • Lee, Dong-Suk
    • Applied Biological Chemistry
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    • v.8
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    • pp.87-93
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    • 1967
  • 1) For the micro-analysis of mercury in plant materials, the method of Furutani was shown to be the simplest and most efficient way and the recovery of the assay was about 98%. 2) When the rice grain was soaked in 1/1000 diluted solution of organo-mercury fungicide for 8 hours at the end of March, the amounts of mercury residues in the brown rice and unhulled rice were 8.8 to $9.5\;{\mu}g/g$ seeds and 10.1 to $10.7\;{\mu}g/g$ seeds, respectively. 3) By washing the treated rice seeds with running water for three days, tile residual mercury concentration was reduced to 1/4 to 1/5; thus the mercury residues were 1.86 to $1.92\;{\mu}g/g$ for brown rice and 1.96 to $2.93\;{\mu}g/g$ for unhulled rice. 4) The residual mercury was present more in the unhulled rice than in the brown rice, either before or after washing of the treated seeds. 5) Among the different rice varieties, no difference was observed in mercury residues by seed treatment and washing.

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Studies on the Cellulase produced by Myriococcum of albomyces (Myriococcum albomyces가 생산하는 Cellulase에 관한 연구)

  • Chung, Dong-Hyo
    • Applied Biological Chemistry
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    • v.14 no.1
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    • pp.59-97
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    • 1971
  • As a study on the cellulase of Myriococcum albomyces the culture media for enzyme formation and properties of its crude preparation were investigated and the crude enzyme preparation was further fractionated. The results are summarized as follows: 1. Wheat bran solid culture produced stronger activities of cellulase than rice bran or defatted soy bean meal solid culture. 2. Shaking culture with wheat bran, rice bran or defatted soy bean meal produced higher cellulase activities than solid culture with the corresponding media. 3. The enzyme formation was higher at $45^{\circ}C$ than at $37^{\circ}C$ or $50^{\circ}C$ regardless of the kind of culture medium. 4. The formation of CMCase activity was more promoted by organic nitrogen source than inorganic nitrogen source. 5. The formation of cellulase activities were increased 1.5 to 3.0-fold by adding CMC, Avicel or cellulose powder as an inducer into 5% wheat bran basal medium. 6. Cellulase production using a tank culture procedure with addition of CMC or Avicel as an inducer was the highest at fifth day and thereafter decreased slightly. 7. The crude enzyme preparation showed pH optimum in 4.0 to 4.5, and pH stability in the range of 3.5 to 8.0. Optimum temperature for the activity was $65^{\circ}C$ which was higher than among other cellulases and it was stable at $60^{\circ}C$ for 120 minutes. 8. Dialyzed crude enzyme was activated by $Ca^{++}$ and $Mg^{++}$, but inhibited by $Hg^{++}$, $Cu^{++}$ and $Ag^{+}$. 9. Four different types of cellulase, i. e., fraction I, fraction II-a, fraction II-b, and fraction III were purified from the culture filtrate of Myriococcum albomyces through a sequence of ammonium sulfate fractionation, and elution chromatography on DEAE-Sephadex A-25, Amberlite CG-25 type 2 and hydroxyapatite columns. 10. These four cellulase fractions were showed to be homogenous by electrophoresis and ultracentrifugation and also gave a typical ultraviolet absorption spectrum of protein. 11. Four purified fraction showed different specificity toward substrates, fraction I has a stronger activity toward Avicel, cellulose powder, and gauze than that of other cellulase fractions. Fraction II-a had a powerful activity toward cellobiose but it was almost inactive agaisnt fibrous cellulose contrary to fraction I. On the contrary, the main component fraction II-b had a fairly higher activity on CMC and Avicel. Activity of fraction II-b toward cellobiose was about one-third of that of fraction II-a and activity on Avicel was lower than that of fraction I. Fraction III had a more powerful activity in decreasing viscosity of CMC. 12. Final hydrolysis products of fibrous cellulose by each fraction were cellobiose and glucose. Whereas oligosaccharides were predominant in the early stage of hydrolysis, prolonged reaction produced more glucose than cellobiose. Fraction I and fraction II-a acted synergically on Avicel. 13. Optimum pH for the activities of cellulase fraction I, fraction II-a, fraction II-b and fraction III were found to be 5.5, 5.0, 4.0 and $4.0{\sim}4.5$, respectively. These fractions were found to be stable in the range of pH $3.0{\sim}7.5$. 14. Optimum temperature for the activities of fraction I, fraction II-a, fraction II-b, and fraction III were $50^{\circ}C$, $55^{\circ}C$, $60^{\circ}C$ and $55^{\circ}C$, respectively. No less of activity was found by heating 120 minutes at $55^{\circ}C$ and fraction II-a was more stable than the others at $60^{\circ}C$. 15. Fraction I and fraction II-b were activated by $Ca^{++}$ and $Mg^{++}$ but inhibited by $Hg^{++}$ and $Ag^{+}$.

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Immunohistochemical Localization of NMDA Receptor in the Auditory Brain Stem of Postnatal 7, 16 Circling Mouse (생후 7일, 16일된 circling mouse 청각 뇌줄기에서 N-메틸-D 아스파르트산염 수용체(NMDA receptor)에 대한 면역염색학적 분포)

  • Choi, In-Young;Park, Ki-Sup;Kim, Hye-Jin;Maskey, Dhiraj;Kim, Myeung-Ju
    • Applied Microscopy
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    • v.40 no.2
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    • pp.53-64
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    • 2010
  • Glutamate receptors may play a critical role in the refinement of developing synapses. The lateral superior olivary nucleus (LSO)-medial nucleus of trapezoid body (MNTB) synaptic transmission in the mammalian auditory brain stem mediate many excitatory transmitters such as glutamate, which is a useful model to study excitatory synaptic development. Hearing deficits are often accompanied by changes in the synaptic organization such as excitatory or inhibitory circuits as well as anatomical changes. Owing to this, circling mouse whose cochlea degenerates spontaneously after birth, is an excellent animal model to study deafness pathophysiology. However, little is known about the development regulation of the subunits composing these receptors in circling mouse. Thus, we used immunohistochemical method to compare the N-Methyl-D-aspartate receptor (NMDA receptor) NR1, NR2A, NR2B distribution in the LSO which project glutamergic excitatory input into the auditory brainstem, in circling mouse of postnatal (p) 7 and 16, which have spontaneous mutation in the inner ear, with wild-type mouse. The relative NMDAR1 immunoreactive density of the LSO in circling mouse p7 was $128.67\pm8.87$ in wild-type, $111.06\pm8.04$ in heterozygote, and $108.09\pm5.94$ in homozygote. The density of p16 circling mouse was $43.83\pm10.49$ in wild-type, $40\pm13.88$ in heterozygote, and $55.96\pm17.35$ in homozygote. The relative NMDAR2A immunoreactive density of LSO in circling mouse p7 was $97.97\pm9.71$ in wild-type, $102.87\pm9.30$ in heterozygote, and $106.85\pm5.79$ in homozygote. The density of LSO in p16 circling was $47.4\pm20.6$ in wild-type, $43.9\pm17.5$ in heterozygote, and $49.2\pm20.1$ in homozygote. The relative NMDAR2B immunoreactive density of LSO in circling mouse p7 was $109.04\pm6.77$ in wild-type, $106.43\pm10.24$ in heterozygote, and $105.98\pm4.10$ in homozygote. the density of LSO in p16 circling mouse was $101.47\pm11.5$ in wild-type, $91.47\pm14.81$ in heterozygote, and $93.93\pm15.71$ in homozygote. These results reveal alteration of NMDAR immunoreactivity in LSO of p7 and p16 circling mouse. The results of the present study are likely to be relevant to understand the central change underlying human hereditary deafness.

Characteristics of Everyday Movement Represented in Steve Paxton's Works: Focused on Satisfyin' Lover, Bound, Contact at 10th & 2nd- (스티브 팩스톤(Steve Paxton)의 작품에서 나타난 일상적 움직임의 특성에 관한 연구: , , 를 중심으로)

  • KIM, Hyunhee
    • Trans-
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    • v.3
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    • pp.109-135
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    • 2017
  • The purpose of this thesis is to analyze characteristics of everyday movement showed in performances of Steve Paxton. A work of art has been realized as a special object enjoyed by high class people as high culture for a long time. Therefore, a gap between everyday life and art has been greatly existed, and the emergence of everyday elements in a work of art means that public awareness involving social change is changed. The postmodernism as the period when a boundary between art and everyday life is uncertain was a postwar society after the Second World War and a social situation that rapidly changes into a capitalistic society. Changes in this time made scholars gain access academically concepts related to everyday life, and affected artists as the spirit of the times of pluralistic postmodernism refusing totality. At the same period of the time, modern dance also faced a turning point as post-modern dance. After the Second World War, modern dance started to be evaluated as it reaches the limit, and at this juncture, headed by dancers including the Judson Dance Theatre. Acting as a dancer in a dance company of Merce Cunningham, Steve Paxton, one of founders of the Judson Dance Theatre, had a critical mind of the conditions of dance company with the social structure and the process that movement is made. This thinking is showed in early performances as an at tempt to realize everyday motion it self in performances. His early activity represented by a walking motion attracted attention as a simple motion that excludes all artful elements of existing dance performances and is possible to conduct by a person who is not a dancer. Although starting the use of everyday movement is regarded as an open characteristic of post-modern dance, advanced researches on this were rare, so this study started. In addition, studies related to Steve Paxton are skewed towards Contact Improvisation that he rose as an active practician. As the use of ordinary movement before he focused on Contact Improvisation, this study examines other attempts including Contact Improvisation as attempts after the beginning of his performances. Therefore, the study analyzes Satisfyin' Lover, Contact at 10th & 2nd and Bound that are performances of Steve Paxton, and based on this, draws everyday characteristics. In addition, related books, academic essays, dance articles and reviews are consulted to consider a concept related to everyday life and understand dance historical movement of post-modern dance. Paxton attracted attention because of his activity starting at critical approach of movement of existing modern dance. As walking of performers who are not dancers, a walking motion showed in Satisfyin' Lover gave esthetic meaning to everyday movement. After that, he was affected by Eastern ideas, so developed Contact Improvisation making a motion through energy of the natural laws. In addition, he had everyday things on his performances, and used a method to deliver various images by using mundane movement and impromptu gestures originating from relaxed body. Everyday movement of his performances represents change in awareness of performances of the art of dancing that are traditionally maintained including change of dance genre of an area. His activity with unprecedented attempt and experimentation should be highly evaluated as efforts to overcome the limit of modern dance.

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The Framework of Research Network and Performance Evaluation on Personal Information Security: Social Network Analysis Perspective (개인정보보호 분야의 연구자 네트워크와 성과 평가 프레임워크: 소셜 네트워크 분석을 중심으로)

  • Kim, Minsu;Choi, Jaewon;Kim, Hyun Jin
    • Journal of Intelligence and Information Systems
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    • v.20 no.1
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    • pp.177-193
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    • 2014
  • Over the past decade, there has been a rapid diffusion of electronic commerce and a rising number of interconnected networks, resulting in an escalation of security threats and privacy concerns. Electronic commerce has a built-in trade-off between the necessity of providing at least some personal information to consummate an online transaction, and the risk of negative consequences from providing such information. More recently, the frequent disclosure of private information has raised concerns about privacy and its impacts. This has motivated researchers in various fields to explore information privacy issues to address these concerns. Accordingly, the necessity for information privacy policies and technologies for collecting and storing data, and information privacy research in various fields such as medicine, computer science, business, and statistics has increased. The occurrence of various information security accidents have made finding experts in the information security field an important issue. Objective measures for finding such experts are required, as it is currently rather subjective. Based on social network analysis, this paper focused on a framework to evaluate the process of finding experts in the information security field. We collected data from the National Discovery for Science Leaders (NDSL) database, initially collecting about 2000 papers covering the period between 2005 and 2013. Outliers and the data of irrelevant papers were dropped, leaving 784 papers to test the suggested hypotheses. The co-authorship network data for co-author relationship, publisher, affiliation, and so on were analyzed using social network measures including centrality and structural hole. The results of our model estimation are as follows. With the exception of Hypothesis 3, which deals with the relationship between eigenvector centrality and performance, all of our hypotheses were supported. In line with our hypothesis, degree centrality (H1) was supported with its positive influence on the researchers' publishing performance (p<0.001). This finding indicates that as the degree of cooperation increased, the more the publishing performance of researchers increased. In addition, closeness centrality (H2) was also positively associated with researchers' publishing performance (p<0.001), suggesting that, as the efficiency of information acquisition increased, the more the researchers' publishing performance increased. This paper identified the difference in publishing performance among researchers. The analysis can be used to identify core experts and evaluate their performance in the information privacy research field. The co-authorship network for information privacy can aid in understanding the deep relationships among researchers. In addition, extracting characteristics of publishers and affiliations, this paper suggested an understanding of the social network measures and their potential for finding experts in the information privacy field. Social concerns about securing the objectivity of experts have increased, because experts in the information privacy field frequently participate in political consultation, and business education support and evaluation. In terms of practical implications, this research suggests an objective framework for experts in the information privacy field, and is useful for people who are in charge of managing research human resources. This study has some limitations, providing opportunities and suggestions for future research. Presenting the difference in information diffusion according to media and proximity presents difficulties for the generalization of the theory due to the small sample size. Therefore, further studies could consider an increased sample size and media diversity, the difference in information diffusion according to the media type, and information proximity could be explored in more detail. Moreover, previous network research has commonly observed a causal relationship between the independent and dependent variable (Kadushin, 2012). In this study, degree centrality as an independent variable might have causal relationship with performance as a dependent variable. However, in the case of network analysis research, network indices could be computed after the network relationship is created. An annual analysis could help mitigate this limitation.

A Study on the Amino Acid Components Soil Humus Composition (토양부식산(土壤腐植酸)의 형태별(形態別) Amino 산(酸) 함량(含量)에 관(關)한 연구(硏究))

  • Kim, Jeong-Je;Lee, Wi-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.21 no.3
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    • pp.254-263
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    • 1988
  • Contents and distribution of amino acids in the humic acid and fulvic acid fractions of different types ($R_p$, B, A, P) were investigated. Extracted humic and fulvic acids were purified and analyzed. The results are summarized as the following: (1) Composition of Humus The total humus ($H_T$), amount of humic acid (a), amount of fulvic acid (b), and ${\Delta}logK$ all decrease in the order of $R_p$ > B > A > P type. The same trend was observed in the total nitrogen and carbon. (2) Contents and composition of amino acids in humic acids. 1) The total amounts of amino acids in the humic acid fraction of different types were in the following order for soils under coniferous forest trees: $R_p$ > B > A > P type, but for soils under deciduous forest trees the order was P > A > $R_p$ > B type. There were positive correlationships between total amino acids and total carbon and ${\Delta}logK$ for humic acids from soils under coniferous forest trees, but a negative correlationship was existed. between total amino acids and C/N ratios. No significant correlation was found for samples taken from soils under deciduous forest trees. 2) The ratios of one group of amino acids to the others were compared. The ratios of acidic amino acids were in the order of P > $R_p$ > B > A type. those of neutral amino acids followed the order of $R_p$ > B > A > P type and those of the basic amino acids were in the order of B > A >$R_p$ > P type for soils under coniferous forest trees. Contents of total amino acids were in the order of the neutral > the acidic > the basic amino acids. For the soils under deciduous forest trees the order of the ratio was different. Acidic amino acids followed the order of A > P > B > $R_p$ type, neutral ones followed the order of P > $R_p$ > A > B type, and the basic amino acids did the order of $$P{\geq_-}$$ A > B $$\geq_-$$ $-R_p$ type where the difference was very small. 3) In general aspartic aicd, glycine and glutamic acid were the major components in all samples. Histidine, tyrosine and methionine belonged to the group contained in a small amount. (3) Contents and composition of amino acids in fulvic acids. 1) The total amounts of amino acids of different types of fulvic acids were in the order of $R_p$ > B > P > A type regardless of origin of samples. There were positive correlationships observed between the toal amino acids and total carbon and ${\Delta}logK$ for soils under coniferous forest trees. For soils under deciduous forest trees, positive correlationships were observed among total amino aicds, total nitrogen, total humus ($H_T$), total humic aicd (a), and ${\Delta}logK$, but a negative correlationship existed between total amino acids and C/N ratio. 2) Thr ratio among acidic amino acids, neutral amino acids and basic amino acids of different types were $R_p$ > B > P > A type. In this respect there was no difference between the two soils. 3) In general glycine, aspartic acid, and alanine were the major constituents in all samples of different types, while tyrosine and methionine were contained in a small amount. Virtually no amount of arginine was measured.

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Development of Analytical Method for Detection of Fungicide Validamycin A Residues in Agricultural Products Using LC-MS/MS (LC-MS/MS를 이용한 농산물 중 살균제 Validamycin A의 시험법 개발)

  • Park, Ji-Su;Do, Jung-Ah;Lee, Han Sol;Park, Shin-min;Cho, Sung Min;Shin, Hye-Sun;Jang, Dong Eun;Cho, Myong-Shik;Jung, Yong-hyun;Lee, Kangbong
    • Journal of Food Hygiene and Safety
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    • v.34 no.1
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    • pp.22-29
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    • 2019
  • Validamycin A is an aminoglycoside fungicide produced by Streptomyces hygroscopicus that inhibits trehalase. The purpose of this study was to develop a method for detecting validamycin A in agricultural samples to establish MRL values for use in Korea. The validamycin A residues in samples were extracted using methanol/water (50/50, v/v) and purified with a hydrophilic-lipophilic balance (HLB) cartridges. The analyte was quantified and confirmed by liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005~0.5 ng) into a blank extract with $R^2$ > 0.99. The limits of detection and quantification were 0.005 and 0.01 mg/kg, respectively. For validation validamycin A, recovery studies were carried out three different concentration levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n = 5) with five replicates at each level. The average recovery range was from 72.5~118.3%, with relative standard deviation (RSD) less than 10.3%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the NIFDS (National Institute of Food and Drug Safety) guideline (2016). Therefore, the proposed analytical method is accurate, effective and sensitive for validamycin A determination in agricultural commodities.