• Journal of Pharmaceutical Investigation
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• 제22권2호
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• pp.97-104
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• 1992

The purpose of this study was (i) to determine whether protease inhibition by medium chain fatty acids such as sodium caprate, sodium caprylate and sodium laurate led to suppression of insulin proteolysis over a range of insulin concentrations and (ii) elucidate preventing effect of the enhancers on molecular self-association of insulin in pH 7.4 phosphate buffer isotonic solution. To this end, the rate of insulin proteolysis in nasal tissue supernatants of the albino rabbits was determined in the presence of $0.1{\sim}2%$ sodium caprylate, sodium caprate and sodium laurate at insulin concentrations ranging from $5\;to\;100\;{\mu}M$. At fatty acid salts concentration lower than 0.5%, insulin proteolysis was accelerated but the enhancers of high concentration (>1%) reduced the rate of insulin proteolysis. These effects were dependent upon insulin concentration and chain length of fatty acid salts. Circular dichroism spectra of insulin solutions were then determined. Monomer fraction of insulin was increased with increasing sodium caprate. Therefore, half-life decrease of insulin at low concentrations of the enhancers was attributed to deaggregation of insulin by the enhancers, increasing the proportion of monomers available for nasal proteolysis. And the increase of half-life at high concentration of the enhancers was attributed to inhibitory effect on protease rather than the effect of monomer fraction.

• 한국농공학회논문집
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• 제60권2호
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• pp.25-36
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• 2018

Drip irrigation system is a low energy cost method which can efficiently save and supply water by dropping water slowly on the crop's root zone during crop growth. In the drip irrigation system, disk filters take an important role to physically remove impurity (inorganic and suspended organic) particles present in agricultural water which can cause emitter clogging. For the purpose, both top-and-bottom surfaces of the disk are grooved in micron size flowing from outside to inside. However, many congested flow paths in disk filter media incur higher head loss of inflow water resulting in relatively decreasing velocities depending on operation time than sand and mesh filters. Therefore, it is important to optimize the structure of disk filter in micro irrigation system. The head loss of disk filter media takes also charge of more than 60 % of total head loss in whole disk filter. This study is to find the appropriate cross-sectional shape of the disk groove to minimize the head loss by executing the experiment. The experiment used three disk filters that have similar filter body but have a half-elliptic and two kinds of triangular cross sections. The experimental results showed that the disk filter with half-elliptic cross sections of disk grooves have less head loss than the disk filter with regular triangular one.

• 정보관리학회지
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• 제22권3호
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• pp.379-408
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• 2005

본 연구는 광복이후 최근 60년간 발표된 우리나라문헌정보학 논문의 주제 및 간행시기별 분포를 조사하고, 이곳에 인용된 외국 문헌정보학 문헌의 주제 및 인용시기별 분포와 그 반감기를 조사함과 동시에 타 학문 분야와의 관련성을 추적함으로써 우리나라 문헌정보학 연구의 동향 및 문헌정보학과 타 학문 분야와의 연계성을 밝히고자 하였다. 그 결과 첫째, 우리나라 문헌정보학 연구의 핵심 주제는 시간의 흐름에 따라 주된 연구 주제가 출현하고 쇠퇴하며, 논문의 주제와 간행시기 사이에 상관성이 있음을 입증하였다. 둘째, 피인용 외국 문헌정보학 문헌의 주제는 인용시기 간에 상관성이 존재하며, 반감기는 평균 10년 미만이지만 주제에 따라 그 반감기에 차이가 있음을 밝혔다. 셋째, 피인용 타 학문 분야문헌의 주제는 인용시기 사이에 상관성이 있으며, 반감기는 평균 10년 미만이지만 주제에 따라 그 반감기에 차이가 있음을 밝혔다.

• Journal of Nutrition and Health
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• 제25권6호
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• pp.461-467
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• 1992

Total parenteral nutrition(TPN)의 구성성분으로써 지방질 수액제의 사용은 점차 많아지고 있지만 사용량이나 사용대상에 대해서는 아직도 규명해야 할 것이 많다. 본 연구에서는 시판 지방질 수액제들을 사용했을 때 이들이 혈청 지질변화에 어떠한 영향을 미치는가를 비교검토하였다. 각각의 시판 지방질 수액제를 12명의 정상적인 사람에게 주사한 후 5분 간격으로 혈액을 채취하여 혈청내 각종 지질의 변화를 관찰하였다. 혈청내에서 지질이 감소되는 속도를 계산하기 위하여 혈청중 중성지방의 fractional removal rate(K)와 반감시간(t/2)를 intravenous fat tolerance test(IVFTT)를 사용하여 계산하였다. 측정한 각종 항목에서 두 시판 지방질 사이에 통계적 차이를 볼수 없었으며 어떤 부작용도 관찰되지 않았다. 또한 두 제품 모두 혈액중의 지질감소, 속도가 유사하였다.

• 한국도서관정보학회지
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• 제48권2호
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• pp.263-293
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• 2017

이 연구는 대학도서관 대출데이터를 활용하여 이용자들의 대출행태를 장서의 대출수명과 주제영역, 특정 이용자층과의 연관성 등의 다양한 관점에서 분석하였다. K대학도서관의 2006년부터 2015년까지 10년간 이용자들의 연도별 대출행태는 매해 20%의 대출도서가 전체 대출의 50%를 차지한다는 '대출도서 20/50 법칙'을 따르는 것으로 확인하였다. 또한 각 대출도서의 도서연령과 대출횟수의 연령별 누적분포를 구하여 도서 반감기를 정의하고 이를 수식화하였다. 종단적 관점에서의 핵심장서를 산출하여 그 특성을 주제별, 구성원별, 계열별, 연도별 등의 측면에서 분석하였다. 종단적 관점의 전체 대출도서와 핵심장서의 대출패턴은 모든 측면에서 매우 상이하게 분석되어 10년 동안 꾸준히 핵심장서로 분류되는 도서들의 역할이 있는 것으로 나타났다. 이는 10년간 꾸준히 대출되는 도서, 즉 핵심장서의 특성이 명확하다는 의미이며, 이러한 특성을 반영한 효율적인 장서구성정책을 개발할 필요성이 있다는 근거가 된다.

• 한국토양환경학회지
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• 제4권1호
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• pp.13-23
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• 1999

본 연구에서는 기아상태에 있는 토양 미생물, Arthrobacter crystallopoietes cell의 2-hydroxypyridine대사능력의 변화 와 이 미생물의 대사능력에 대한 부식산의 영향에 대해 다루어졌다. 기질 2-HP에 대한 대수기 세포(exponential phase cell)는 적응기 세포(lag phase cell)와 비교할 때 기아상태에 있어서도 더 높은 2-HP대사능력을 보여 기아상태 3일 후 대수기 세포에서 2-HP반감기는 14시간으로 나타난 반면 적응기 세포의 경우 46.5시간으로 나타났다. 부식산은 기아상태에서 이 미생물 세포의 유도효소, 2-HP monooxygenase의 안정성을 높여주어 기아시간 2일 후 표준조건에서 기아상태에 있던 미생물의 효소활성이 처음의 1.5%로 남아 있는 반면 0.2% 부식산 용액에서 기아상태로 있던 미생물의 효소활성은 12%까지 남아 있었다. 기아시간 14일 후 까지도 부식산 용액 속에서 기아상태로 있던 이 미생물 세포의 2-HP대사능력은 표준 조건의 것에 비해 월등히 높아 2-HP반감기를 비교해 보면 표준 조건의 경우 43시간인 반면 부식산의 경우 1.25시간으로 나타났다.

• 미생물학회지
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• 제25권2호
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• pp.94-102
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• 1987

Rat liver LDH A-cDNA has been isolated from a .lambda.gt11-rat lover cDNA library and partially characterized. The size of the isolated rat liver LDH A-cDNA if shown to be 1.6Kb and restriction enzyme sites for the rat liver LDH A-cDNA are also mapped. 682-nucleotide sequence coding for 3'-end of rat liver LDH A-cDNA has been analyzed and compared to the nucleotide sequence of the same region of rat $C_6$-glioma cell LDH A-cDNA which has been cloned from the hormonally stimulated cell cultures. The result shows that 177 nucleotide sequences coding for the C-terminal 59-amino acids are identical but 505 nucleotide sequences of 3'-nontranslated region of the two LSH A-cDNA exhibit characteristic differences in thier nucleotide sequences. Computer analysis for the folding structures for 3'-end 400 nucleotide sequences of the two LDH A-cDNA shows a possibility implying that the two LDH A-mRNAs isolated from different tissues of rats may have different half life and therefore their translational efficiency may be different. It has been previously demonstrated that isoproterenol stimulated rat $C_6$ -glioma cell cultures produce LDH A-mRNA showing 2 to 3-fold longer half life in comparison to that of noninduced LHD A-mRNA. The result therefore support for the idea that hormonally stimulated rat $C_6$-glioma cells may produce LDH A-mRNA containing different nucleotide sequences at the 3'-end nontranslated region by which the hormonally induced LDH A-mRNA could have more stable secondary mRAN structure in comparison to that of noninduced LDH A-mRNA.

• IMMUNE NETWORK
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• 제3권4호
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• pp.276-280
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• 2003

Background: Peroxidases (Prx) of the peroxiredoxin family reduce hydrogen peroxide and alkyl hydroperoxides to water and alcohol respectively. Hydrogen peroxide is implicated as an intracellular messenger in various cellular responses such as proliferation and differentiation. And Prx I activity is regulated by Cdc-2 mediated phosphorylation. This work was undertaken to investigate the proliferation role of peroxiredoxin III as a member of Prx family in Prx III overexpressed HeLa cell line. Methods: To provide further evidence of proliferation, we selected Prx III stably expressed HeLa Tet-off cell lines. Cell proliferation was examined by using proliferation reagent WST-1 in the presence or absence of doxycycline. Prx III, 2-cys Prx enzymes exist as homodimer. The activation of Prx III heterodimer with induced and endogenous Prx III was examined by immunoprecipitation. Results: Immunoprecipitation analysis of the induced and endogenous Prx III with anti-myc showed that the induced wild type (WT) and dominant negative (DN) Prx III from HeLa Prx III Tet-off stable cell heterodimerized with endogenous Prx III each other. And the expression level of induced Prx III was examined after addition of doxycycline. By 72 hr, the expression level of induced Prx III was diminished gradually and the half-life of the induced wild type Prx III was approximately 17 hr. The proliferation experiment demonstrated that the relative proliferation value of induced and endogenous WT Prx III stable cell has no changes but the DN Prx III induced HeLa Tet-off stable cells were lower than endogenous Prx III. Conclusion: In conclusion, the HeLa dominant negative Prx III Tet-off stable cells were decreased the proliferation.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.99-99
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• 2001

The acid-labile subunit (ALS) associates with insulin-like growth factor (IGF)-I or -II and IGF binding protein-3 (IGFBP-3) to form a 150-kD complex in the circulation. This complex is thought to regulate the serum IGFs by restricting them in the vascular system and promotes their endocrine actions. Little is known about how ALS binds to IGFBP3, which connects the IGFs to ALS. Xenopus oocyte was utilized to study the function of ALS in assembling IGFs into the ternary complexes. Xenopus oocyte was shown to correctly translate in vitro transcribed mRNAs of ALS and IGFBP3. IGFBP3 and ALS mRNAs were injected in mixture and their products were immunoprecipitated by antisera against ALS and IGFBP3. Contrary to the traditional reports that ALS interacts only with IGF-bound IGFBP3, this study shows that ALS is capable of forming a binary complex with IGFBP3 in the absence of IGF. When cross-linked by disuccinimidyl substrate, band representing ALS-IGFBP3 complex was evident on the PAGE. IGFBP3 movement was monitored according to the distribution between the hemispheres. Following a localized translation in the vegetal hemisphere, IGFBP3 was shown to remain in the vegetal half in the presence of ALS. Different from wild type IGFBP3, however, mutant IGFBP3 freely diffused into the animal half despite the presence of ALS. Taken together, this study suggests that ALS may play an important role in sequestering IGFBP3 polypeptides via the intermolecular aggregation. Studies using this heterologous model will lead to a better understanding of the IGFBP3 and ALS assembling into the ternary structure and circulating IGF system.

• 대한핵의학회지
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• 제38권2호
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• pp.198-204
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• 2004

Tumor cell proliferation is considered to be a useful prognostic indicator of tumor aggressiveness and tumor response to therapy but in vitro measurement of individual proliferation is complex and tedious work. PET imaging provides a noninvasive approach to measure tumor growth rate in situ. Early approaches have used $^{18}F$-FDG or methionine to monitor proliferation status. These 2 tracers detect changes in glucose and amino acid metabolism, respectively, and therefore provide only an indirect measure of proliferation status. More recent studies have focused on DNA synthesis itself as a marker of cell proliferation. Cell lines and tissues with a high proliferation rate require high rates of DNA synthesis. $[^{11}C]Thymidine$ was the first radiotracer for noninvasive imaging of tumor proliferation. The short half-life of $^{11}C$ and rapid metabolism of $[^{11}C]Thymidine$ in vivo make the radiotracer less suitable for routing use. Halogenated thymidine analogs such as 5-iodo-2-deoxyuridine (IUdR) can be successfully used as cell proliferation markers for in vitro studies because these compounds are rapidly incorporated into newly synthesized DNA. IUdR has been evaluated as a potential in vivo tracer in nuclear medicing but the image qualify and the calculation of proliferation rates are impaired by its rapid in vivo degradation. Hence, the thymidine analog $3'-deoxy-3'-^{18}F-fluorothymidine$ (FLT) was recently introduced as a stable proliferation marker with a suitable nuclide half-life and stable in vivo. $[^{18}F]FLT$ is phosphorylated to 3-fluorothymidine monophosphate by thymidine kinase 1 and reflects thymidine kinase 1 activity in proliferating cell. $[^{18}F]FLT$ PET is feasible in clincal use and well correlates with cellular proliferation. Choline is a precursor for the biosynthesis of phospholipids (in particular, phosphatidylcholine), which is the essential component of all eukaryotic cell membranes and $[^{11}C]choline$, which is a new marker for cellular proliferation.