• Molecules and Cells
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• 제41권10호
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• pp.909-916
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• 2018

In pancreatic ${\beta}$ cells, glucose stimulates the biosynthesis of insulin at transcriptional and post-transcriptional levels. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), also named hnRNP I, acts as a critical mediator of insulin biosynthesis through binding to the pyrimidine-rich region in the 3'-untranslated region (UTR) of insulin mRNA. However, the underlying mechanism that regulates its expression in ${\beta}$ cells is unclear. Here, we report that glucose induces the expression of PTBP1 via the insulin receptor (IR) signaling pathway in ${\beta}$ cells. PTBP1 is present in ${\beta}$ cells of both mouse and monkey, where its levels are increased by glucose and insulin, but not by insulin-like growth factor 1. PTBP1 levels in immortalized ${\beta}$ cells established from wild-type (${\beta}IRWT$) mice are higher than levels in ${\beta}$ cells established from IR-null (${\beta}IRKO$) mice, and ectopic re-expression of IR-WT in ${\beta}IRKO$ cells restored PTBP1 levels. However, PTBP1 levels were not altered in ${\beta}IRKO$ cells transfected with IR-3YA, in which the Tyr1158/1162/1163 residues are substituted with Ala. Consistently, treatment with glucose or insulin elevated PTBP1 levels in ${\beta}IRWT$ cells, but not in ${\beta}IRKO$ cells. In addition, silencing Akt significantly lowered PTBP1 levels. Thus, our results identify insulin as a pivotal mediator of glucose-induced PTBP1 expression in pancreatic ${\beta}$ cells.

• 천문학회지
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• 제51권6호
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• pp.197-206
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• 2018

We present the analysis of KMT-2016-BLG-0212, a low flux-variation ($I_{flux-var}{\sim}20mag$) microlensing event, which is in a high-cadence (${\Gamma}=4hr^{-1}$) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf (q = 0.037) and sub-Neptune (q < $10^{-4}$) companions. Future high-resolution imaging should easily distinguish between these solutions.

• Mycobiology
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• 제51권6호
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• pp.452-462
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• 2023

Opportunistic infections due to Cryptococcus neoformans and C. gattii species complexes continue to rise unabated among HIV/AIDS patients, despite improved antifungal therapies. Here, we collected a total of 20 environmental and 25 presumptive clinical cryptococcal isolates from cerebrospinal fluid (CSF) samples of 175 patients enrolled in an ongoing clinical trial Ambition 1 Project (Botswana-Harvard Partnership). Identity confirmation of the isolates was done using MALDI-TOF MS and PCR. We describe the diversity of the isolates by PCR fingerprinting and sequencing (Oxford Nanopore Technology) of the intergenic spacer region. Mating types of the isolates were determined by amplification of the MAT locus. We report an unusual prevalence of 42.1% of C. neoformans × C. deneoformans hybrids Serotype AD (n = 16), followed by 39.5% of C. neoformans Serotype A (n = 15), 5.3% of C. deneoformans, Serotype D (n = 2), 7.9% of C. gattii (n = 3), and 5.3% of C. tetragattii (n = 2) in 38 representative isolates that have been characterized. Mating type-specific PCR performed on 38 representative environmental and clinical isolates revealed that 16 (42.1%) were MATa/MAT𝛼 hybrids, 17 (44.7%) were MAT𝛼, and five (13.2%) possessed MATa mating type. We used conventional and NGS platforms to demonstrate a potential link between environmental and clinical isolates and lay a foundation to further describe mating patterns/history in Botswana.

• 한국학교ㆍ지역보건교육학회지
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• 제12권3호
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• pp.29-41
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• 2011

배경 및 목적 : 미국과한국양국의대학생의음주문제는심각한사회문제이며, 대학생의음주문제를예방하기 위한 다양한 노력들이 시도되고 있다. 본 연구는 미국과 한국대학생들의 음주와 폭음에 대한 인식 및 태도에 차이가 있는지를 비교 분석하기 위해 설계되었다. 방법 : 데이터는 2001년 미국의 하버드 보건대학원의 College Alcohol Study (CAS) 팀에서 미국의 120개 4년제 대학에서 10,904명에게서 조사한 원자료와 한국에서는2003년 삼육대학교 보건복지대학원의 Korean College Alcohol Study (KCAS) 팀에서 전국의 60개 4년제 대학의 2,385명의 원자료를 함께 통합하여 사용하였다. 이 자료의 특징은CAS에서 개발한설문지를 한국과 미 국양측에서 공동으로 사용하여 양 국가를 대표한 4년제 대학생의 표본을 대상으로 음주와 관련된 조사를 수행한 점이다. 결과 : 한국남학생들이 폭음할 기회가7.74배더많고 여학생의 경우는3.36배 더많다. 지난 한달동안 3회 이상 술 취한 경험율에서 한국 남학생들의 경험율이 34.3%로 미국의 20.4%보다 많고, 여학생의 경우도 24.6%로 미국 여학생의 11.1%보다 현저히 더 많다. 한국 대학생들의 폭음자 비율이 미국 대학생들의 폭음자 비율보다 많은 것과같이, 한국 대학생들이 미국의 대학생들 보다 폭음이 안전한 것으로 인식하고 있으며, 음주에있어서도더욱허용적인태도를가지고있다. 한국남학생의78.4%와 여학생의67.3%가 폭음 이상의 량을 안전하다고 인식하고 있다(미국은 남학생은 50.3%, 여학생은 34.1%). 폭음에 해당하는 음주량(남자는5잔 이상, 여자는4잔 이상)을안전하다고인식하는정도에서한국의대학생들이미국의대학생들에 비해서 남학생은 4.06배, 여학생이 3,96배 더 높다. 결론 : 한국 학생들 중에서도 음주의 량이 더 많은 학생들이 다른 학생들보다 음주와 술 취함과 폭음에 관하여 더욱 허용적이고, 안전한 음주에 대해 더욱 둔감한 태도와 신념을 보이고 있다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2008년도 International Meeting of the Microbiological Society of Korea
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• pp.62-64
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• 2008

A major hurdle to the development of RNA interference as therapy for HIV infection is the delivery of siRNA to T lymphocytes which are difficult cells to transfect even in vitro. We have employed a single chain antibody to the pan T cell surface antigen CD7 was conjugated to an oligo-9-arginine peptide (scFvCD7-9R) for T cell-specific siRNA delivery in NOD/SCIDIL2${\gamma}$-/- mice reconstituted with human peripheral blood lymphocytes (Hu-PBL). Using a novel delivery, we first show that scFvCD7-9R efficiently delivered CD4 siRNA into human T cells in vitro. In vivo administration to Hu-PBL mice resulted in reduced levels of surface CD4 expression on T cells. Mice infected with HIV-1 and treated on a weekly basis with scFvCD7-9R-siRNA complexes targeting a combination of viral genes and the host coreceptor molecule CCR5 successfully maintained CD4/CD3 T cell ratios up to 4 weeks after infection in contrast to control mice that displayed a marked reduction in CD4 T cell numbers. p24 antigen levels were undetectable in 3 of the 4 protected mice. scFvCD7-9R/antiviral siRNA treatment also helped maintain CD4 T cell numbers with reduced plasma viral loads in Hu-PBL mice reconstituted with PBMC from donors seropositive for HIV, indicating that this method can contain viral replication even in established HIV infections. Our results show that scFvCD7-9R could be further developed as a potential therapeutic for HIV-1 infection.

• 한국대기환경학회지
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• 제21권3호
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• pp.329-341
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• 2005

The purpose of this study is to study the $PM_{2.5}$ source characteristics affecting the Seoul area using a chemical mass balance (CMB) receptor model. This study was also to evaluate the $PM_{2.5}$ source profiles, which were directly measured and developed. Asian Dust Storm usually occurred in the spring, and very high $PM_{2.5}$ concentrations were observed in the fall among the sampling periods. So the ambient data collected in the spring and fall were evaluated. The CMB model results as well as the $PM_{2.5}$ source profiles were validated using the diagnostic categories, such as: source contribution estimate, t-statistic, R-square, Chi-square, and percent of total mass explained. In the spring months, the magnitude of $PM_{2.5}$ mass contributors was in the following order: Chinese aerosol $(31.7\%)>$ secondary aerosols ($22.3\%$: ammonium sulfate $13.4\%$ and ammonium nitrate $8.9\%)>$ vehicles ($16.1\%$: gasoline vehicle $1.4\%$ and diesel vehicles $14.7\%)>$biomass burning $(15.5\%)>$ geological material $(10.5\%)$. In the fall months, the general trend of the $PM_{2.5}$ mass contributors was the following: biomass burning $(31.1\%)>$ vehicles ($26.9\%$: gasoline vehicle $5.1\%$ and diesel vehicles $21.8\%)>$ secondary aerosols ($23.0\%$: ammonium sulfate $9.1\%$ and ammonium nitrate $13.9\%)>$ Chinese aerosol $(10.7\%)$. The results show that the $PM_{2.5}$ mass in the Seoul area was mainly affected by the Chinese area.

• Journal of Communications and Networks
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• 제11권5호
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• pp.433-444
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• 2009

The bi-directional relay channel is the natural extension of a three-terminal relay channel where node a transmits to node b with the help of a relay r to allow for two-way communication between nodes a and b. That is, in a bi-directional relay channel, a and b wish to exchange independent messages over a shared channel with the help of a relay r. The rates at which this communication may reliably take place depend on the assumptions made on the relay processing abilities. We overview information theoretic limits of the bi-directional relay channel under a variety of conditions, before focusing on half-duplex nodes in which communication takes place in a number of temporal phases (resulting in protocols), and nodes may forward messages in four manners. The relay-forwarding considered are: Amplify and forward (AF), decode and forward (DF), compress and forward (CF), and mixed forward. The last scheme is a combination of CF in one direction and DF in the other. We derive inner and outer bounds to the capacity region of the bi-directional relay channel for three temporal protocols under these four relaying schemes. The first protocol is a two phase protocol where a and b simultaneously transmit during the first phase and the relay r alone transmits during the second. The second protocol considers sequential transmissions from a and b followed by a transmission from the relay while the third protocol is a hybrid of the first two protocols and has four phases. We provide a comprehensive treatment of protocols in Gaussian noise, obtaining their respective achievable rate regions, outer bounds, and their relative performance under different SNR and relay geometries.

• 한국어교육
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• 제29권4호
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• pp.225-254
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• 2018

The purpose of this study is to contrast the patterns of realization and understanding of refusal speech acts between Korean and Thai learners. This study intends to answer the following questions: (1) Do Koreans and Thai learners perform refusal speech acts differently? (2) Do Koreans and Thai learners understand refusal speech acts differently? A DCT and a follow-up interview were conducted to collect data of two groups of 30 native Korean speakers and 30 native Thai speakers. For research question 1, we analyzed the refusal strategy and provided reasons given by Koreans and Thai learners depending on the context. For research question 2, we ran a chi-squared test on the elements of the follow-up interviews, such as the weight of burden of refusing, and whether the participant would actually refuse or not. The differences between the refusal strategies of the two groups could be categorized by the preceding inducing speech act. In refusing a request, the difference was prominent in the apologizing strategy, whereas in refusing a suggestion, the difference was mainly in the direct refusal strategy. When refusing an invitation, the most evident difference was the number of refusal strategies employed. When providing an explanation of refusal to people with high social status, Koreans gave more specific reasons for refusals, whereas Thai learners tended to use more vague reasons. Moreover, when refusing an invitation, Koreans primarily mentioned the relationship, and Thai learners showed the spirit of Greng Jai. When asked the weight of burden of refusing, Koreans felt pressured to refuse a request from people with high social status, and a suggestion or invitation from people with high level of intimacy while Thai learners found it highly difficult to make a refusal in all cases. In answering whether they would actually refuse or not, Koreans tried not to make a refusal to people with high level of intimacy, and such a trend was not evident among the Thai. This study can help us better understand the learner's pragmatic failure, and serve as a basis in establishing a curriculum for teaching speech acts.

• Korean Journal of Radiology
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• 제2권4호
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• pp.210-215
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• 2001

Objective: To investigate the efficacy of gadobenate dimeglumine (GdBOPTA) enhanced MR imaging for the detection of liver lesions in patients with primary malignant hepatic neoplasms. Materials and Methods: Thirty-one patients with histologically proven primary malignancy of the liver were evaluated before and after administration of GdBOPTA at dose 0.05 or 0.10 mmol/kg. T1-weighted spin echo (T1W-SE) and gradient echo (T1W-GRE) images were evaluated for lesion number, location, size and confidence by three off-site independent reviewers and the findings were compared to reference standard imaging (intraoperative ultrasound, computed tomography during arterial portography or lipiodol computed tomography). Results were analyzed for significance using a two-sided McNemar's test. Results: More lesions were identified on Gd-BOPTA enhanced images than on unenhanced images and there was no significant difference in lesion detection between either concentration. The largest benefit was in detection of lesions under 1 cm in size (7 to 21, 9 to 15, 16 to 18 for reviewers A, B, C respectively). In 68% of the patients with more than one lesion, Gd-BOPTA increased the number of lesions detected. Conclusion: Liver MR imaging after Gd-BOPTA increases the detection of liver lesions in patients with primary malignant hepatic neoplasm.

• 천문학회보
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• 제37권1호
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• pp.82.1-82.1
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• 2012

We present results of searching for the Very Low Luminosity Objects (VeLLOs; internal luminosity Lint<0.1Lo) candidates in the Gould Belt's clouds using infrared observations from 3.6 to 70 micron by the Spitzer Space Telescope. More than 100 VeLLO candidates were selected through the criteria by Dunham et al. and our additional ones. The candidates in Northern sky were recently observed with high density tracers such as N2H+ (1-0) and HCN (1-0) using Korea VLBI Network (KVN) 21m telescope at Yonsei site to check their embeddedness in dense gas envelopes. A total of 25 out of 74 VeLLO candidates were detected in either N2H+ or HCN (1-0) line while 9 candidates were detected in both tracers. These are more likely bona fide VeLLOs which need to be studied further in future. In this study the bolometric luminosities for 40 VeLLOs (25 from this study and 15 from Dunham et al.) were estimated and found to be significantly smaller than those given by various theoretical model tracks with constant accretion rate in a BLT diagram, indicating the constant accretion process suggested by standard star formation models can not explain the faintness of the VeLLOs. In the talk we will discuss on some possible explanation of why the VeLLOs are faint.