• The Korean Journal of Physiology and Pharmacology
• /
• 제2권4호
• /
• pp.521-527
• /
• 1998

An important property of the intestine is the ability to secrete fluid. The intestinal secretion is regulated by a number of substances including vasoactive intestinal peptide (VIP), ATP and different inflammatory mediators. One of the most important secretagogues is adenosine during inflammation. However, the controversy concerning the underlying mechanism of adenosine-stimulated $Cl^-$ secretion in intestinal epithelial cells still continues. To investigate the effect of adenosine on $Cl^-$ secretion and its underlying mechanism in the rabbit colon mucosa, we measured short circuit current ($I_{SC}$) under automatic voltage clamp with DVC-1000 in a modified Ussing chamber. Adenosine, when added to the basolateral side of the muocsa, increased $I_{SC}$ in a dose-dependent manner. The adenosine-stimulated $I_{SC}$ response was abolished when $Cl^-$ in the bath solution was replaced completely with gluconate. In addition, the $I_{SC}$ response was inhibited by a basolateral Na-K-Cl cotransporter blocker, bumetanide, and by apical $Cl^-$ channel blockers, dephenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), glibenclamide. Amiloride, an epithelial $Na^+$ channel blocker, and 4,4-diisothiocyanato-stilbene-2,2-disulphonate (DIDS), a $Ca^{2+}-activated$ $Cl^-$ channel blocker, had no effect. In the mucosa pre-stimulated with forskolin, adenosine did not show any additive effect, whereas carbachol resulted in a synergistic potentiation of the $I_{SC}$ response. The adenosine response was inhibited by 10 ${\mu}M$ H-89, an inhibitor of protein kinase A. These results suggest that the adenosine-stimulated $I_{SC}$ response is mediated by basolateral to apical $Cl^-$ secretion through a cAMP-dependent $Cl^-$ channel. The rank order of potencies of adenosine receptor agonists was $5'-(N-ethylcarboxamino)adenosine(NECA)＞N^6-(R-phenylisopropyl)adenosine(R-$ PIA)＞2-[p-(2-carbonylethyl)-phenyl-ethylamino]-5'-N-ethylcarboxaminoadenosine(CGS21680). From the above results, it can be concluded that adenosine interacts with the $A_{2b}$ adenosine receptor in the rabbit colon mucosa and a cAMP-dependent signalling mechanism underlies the stimulation of $Cl^-$ secretion.

• 정보과학회 논문지
• /
• 제42권12호
• /
• pp.1522-1534
• /
• 2015

본 연구에서는 미리 구축해 놓은 학습데이터 없이도 입력된 작문이 주어진 작문 주제에 적합한 내용인지 아닌지를 자동으로 판단할 수 있는 방법을 제안한다. ConceptNet은 다양한 종류의 문서에서 추출한 자연언어 문장들로부터 구축된 그래프 형태의 지식베이스이다. 본 연구에서는 작문 주제에 해당하는 작문 프롬프트(essay prompt)와 ConceptNet만을 이용하여 문서의 주제-이탈 여부를 판별하는 방법을 제안한다. ConceptNet에서 두 개념간의 최단 경로를 찾고 이에 대한 의미 유사도를 계산하는 방법을 제안한다. 이를 이용하여 작문 프롬프트와 수험생 작문 내용을 ConceptNet의 개념들로 매핑하고 이 개념들 사이의 의미 유사도를 계산하여 작문 프롬프트와 수험생 작문 사이의 주제 부합 여부를 판단한다. 8개의 작문 시험을 수행하여 얻은 수험생 작문 데이터에 대하여 평가를 수행한 결과 기존의 연구에 비해 좋은 성능을 얻을 수 있었다. ConceptNet을 활용하면 유의미한 단순 추론이 가능하기 때문에 본 연구에서 제안한 방법은 추론을 요하는 작문 문제에도 적용 가능함을 보였다.

• Korean Journal of Radiology
• /
• 제22권7호
• /
• pp.1152-1162
• /
• 2021

Objective: This study aimed to determine whether there are regional differences in the blood-brain barrier (BBB) permeability of cognitively normal elderly participants and to identify factors influencing BBB permeability with a clinically feasible, 10-minute dynamic contrast-enhanced (DCE) MRI protocol. Materials and Methods: This IRB-approved prospective study recruited 35 cognitively normal adults (26 women; mean age, 64.5 ± 5.6 years) who underwent DCE T1-weighted imaging. Permeability maps (K_trans) were coregistered with masks to calculate the mean regional values. The paired t test and Friedman test were used to compare Ktrans between different regions. The relationships between K_trans and the factors of age, sex, education, cognition score, vascular risk burden, vascular factors on imaging, and medial temporal lobar atrophy were assessed using Pearson correlation and the Spearman rank test. Results: The mean permeability rates of the right and left hippocampi, as assessed with automatic segmentation, were 0.529 ± 0.472 and 0.585 ± 0.515 (K_trans, x 10^-3 min^-1), respectively. Concerning the deep gray matter, the K_trans of the thalamus was significantly greater than those of the putamen and hippocampus (p = 0.007, p = 0.041). Regarding the white matter, the K_trans value of the occipital white matter was significantly greater than those of the frontal, cingulate, and temporal white matter (p < 0.0001, p = 0.0007, p = 0.0002). The variations in K_trans across brain regions were not related to age, cognitive score, vascular risk burden, vascular risk factors on imaging, or medial temporal lobar atrophy in the study group. Conclusion: Our study demonstrated regional differences in BBB permeability (K_trans) in cognitively normal elderly adults using a clinically acceptable 10-minutes DCE imaging protocol. The regional differences suggest that the integrity of the BBB varies across the brains of cognitively normal elderly adults. We recommend considering regional differences in K_trans values when evaluating BBB permeability in patients with neurodegenerative diseases.

• 지능정보연구
• /
• 제24권3호
• /
• pp.221-241
• /
• 2018

지식사회에 들어서며 새로운 형태의 자본으로서 정보의 중요성이 강조되고 있다. 그리고 기하급수적으로 생산되는 디지털 정보의 효율적 관리를 위해 정보 분류의 중요성도 증가하고 있다. 본 연구에서는 기업의 기술사업화 의사결정에 도움이 될 수 있는 맞춤형 정보를 자동으로 분류하여 제공하기 위하여, 기업의 사업 성격을 나타내는 한국표준산업분류(이하 'KSIC')를 기준으로 정보를 분류하는 방법을 제안하였다. 정보 혹은 문서의 분류 방법은 대체로 기계학습을 기반으로 연구되어 왔으나 KSIC를 기준으로 분류된 충분한 학습데이터가 없어, 본 연구에서는 문서간 유사도를 계산하는 방식을 적용하였다. 구체적으로 KSIC 각 코드별 설명문을 수집하고 벡터 공간 모델을 이용하여 분류 대상 문서와의 유사도를 계산하여 가장 적합한 KSIC 코드를 제시하는 방법과 모델을 제시하였다. 그리고 IPC 데이터를 수집한 후 KSIC를 기준으로 분류하고, 이를 특허청에서 제공하는 KSIC-IPC 연계표와 비교함으로써 본 방법론을 검증하였다. 검증 결과 TF-IDF 계산식의 일종인 LT 방식을 적용하였을 때 가장 높은 일치도를 보였는데, IPC 설명문에 대해 1순위 매칭 KSIC의 일치도는 53%, 5순위까지의 누적 일치도는 76%를 보였다. 이를 통해 보다 정량적이고 객관적으로 중소기업이 필요로 할 기술, 산업, 시장정보에 대한 KSIC 분류 작업이 가능하다는 점을 확인할 수 있었다. 또한 이종 분류체계 간 연계표를 작성함에 있어서도 본 연구에서 제공하는 방법과 결과물이 전문가의 정성적 판단에 도움이 될 기초 자료로 활용될 수 있을 것으로 판단된다.

• Korean Journal of Radiology
• /
• 제23권2호
• /
• pp.226-236
• /
• 2022

Objective: This study aimed to explore the myelin volume change in patients with mild traumatic brain injury (mTBI) with post-concussion syndrome (PCS) using a multidynamic multiecho (MDME) sequence and automatic whole-brain segmentation. Materials and Methods: Forty-one consecutive mTBI patients with PCS and 29 controls, who had undergone MRI including the MDME sequence between October 2016 and April 2018, were included. Myelin volume fraction (MVF) maps were derived from the MDME sequence. After three dimensional T1-based brain segmentation, the average MVF was analyzed at the bilateral cerebral white matter (WM), bilateral cerebral gray matter (GM), corpus callosum, and brainstem. The Mann-Whitney U-test was performed to compare MVF and myelin volume between patients with mTBI and controls. Myelin volume was correlated with neuropsychological test scores using the Spearman rank correlation test. Results: The average MVF at the bilateral cerebral WM was lower in mTBI patients with PCS (median [interquartile range], 25.2% [22.6%-26.4%]) than that in controls (26.8% [25.6%-27.8%]) (p = 0.004). The region-of-interest myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (1.87 cm³ [1.70-2.05 cm³] vs. 2.21 cm³ [1.86-3.46 cm³]; p = 0.003) and brainstem (9.98 cm³ [9.45-11.00 cm³] vs. 11.05 cm³ [10.10-11.53 cm³]; p = 0.015). The total myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (0.45 cm³ [0.39-0.48 cm³] vs. 0.48 cm³ [0.45-0.54 cm³]; p = 0.004) and brainstem (1.45 cm³ [1.28-1.59 cm³] vs. 1.54 cm³ [1.42-1.67 cm³]; p = 0.042). No significant correlation was observed between myelin volume parameters and neuropsychological test scores, except for the total myelin volume at the bilateral cerebral WM and verbal learning test (delayed recall) (r = 0.425; p = 0.048). Conclusion: MVF quantified from the MDME sequence was decreased at the bilateral cerebral WM in mTBI patients with PCS. The total myelin volumes at the corpus callosum and brainstem were decreased in mTBI patients with PCS due to atrophic changes.