Over-Expression of Ephrin-A5 in Mice Results in Decreasing the Size of Progenitor Pool through Inducing Apoptosis

Noh, Hyuna,Park, Soochul Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.2

Eph receptors and their ligands, ephrins, mediate cell-to-cell contacts in a specific brain region and their bidirectional signaling is implicated in the regulation of apoptosis during early brain development. In this report, we used the alpha(${\alpha}$)-Cre transgenic line to induce ephrin-A5 over-expression in the distal region of the neural retina. Using this double transgenic embryo, we show that the over-expression of ephrin-A5 was responsible for inducing massive apoptosis in both the nasal and temporal retinas. In addition, the number of differentiated retinal neurons with the exception of the bipolar neuron was significantly reduced, whereas the laminar organization of the mature retina remained intact. Consistent with this finding, an analysis of the mature retina revealed that the size of the whole retina-particularly the nasal and temporal regions-is markedly reduced. These results strongly suggest that the level of ephrin-A5 expression plays a role in the regulation of the size of the retinal progenitor pool in the neural retina.

Proper closure of the optic fissure requires ephrin A5-EphB2-JNK signaling

Noh, Hyuna,Lee, Haeryung,Park, Eunjeong,Park, Soochul The Company of Biologists Limited 2016 Development (Cambridge) Vol.143 No.3

<P>The development of complex organs such as the eye requires a delicate and coordinated balance of cell division and cell death. Although apoptosis is prevalent in the proximoventral optic cup, the precise role it plays in eye development needs to be investigated further. In this study, we show that reduced apoptosis in the proximoventral optic cup prevents closure of the optic fissure. We also show that expression of ephrin A5 (Efna5) partially overlaps with Eph receptor B2 (Ephb2) expression in the proximoventral optic cup and that binding of EphB2 to ephrin A5 induces a sustained activation of JNK. This prolonged JNK signal promotes apoptosis and prevents cell proliferation. Thus, we propose that the unique cross-subclass interaction of EphB2 with ephrin A5 has evolved to function upstream of JNK signaling for the purpose of maintaining an adequate pool of progenitor cells to ensure proper closure of the optic fissure.</P>

The mouse one portal(MOP), all Information for all mice

Hyuna Noh 한국실험동물학회 2020 한국실험동물학회 학술발표대회 논문집 Vol.2020 No.2

In Vivo Expression of EphrinA5-Fc in Mice Results in Cephalic Neural Crest Agenesis and Craniofacial Abnormalities

Noh, Hyuna,Park, Eunjeong,Park, Soochul Korean Society for Molecular and Cellular Biology 2014 Molecules and cells Vol.37 No.1

Eph receptors and their ligands ephrins have been implicated in guiding the directed migration of neural crest cells (NCCs). In this study, we found that Wnt1-Cre-mediated expression of ephrinA5-Fc along the dorsal midline of the dien- and mesencephalon resulted in severe craniofacial malformation of mouse embryo. Interestingly, expression of cephalic NCC markers decreased significantly in the frontonasal process and branchial arches 1 and 2, which are target areas for the migratory cephalic NCCs originating in the dien- and mesencephalon. In addition, these craniofacial tissues were much smaller in mutant embryos expressing ephrinA5-Fc. Importantly, EphA7-positive cephalic NCCs were absent along the dorsal dien- and mesencephalon of mutant embryos expressing ephrinA5-Fc, suggesting that the generation of cephalic NCCs is disrupted due to ephrinA5-Fc expression. NCC explant experiments suggested that ephrinA5-Fc perturbed survival of cephalic NCC precursors in the dorsal midline tissue rather than affecting their migratory capacity, which was consistent with our previous report that expression of ephrinA5-Fc in the dorsal midline is responsible for severe neuroepithelial cell apoptotic death. Taken together, our findings strongly suggest that expression of ephrinA5-Fc decreases a population of cephalic NCC precursors in the dorsal midline of the dien- and mesencephalon, thereby disrupting craniofacial development in the mouse embryos.

Ectopic Expression of Ephrin-A5 Under the EphA8 Promoter at the Anterior Region of the Superior Colliculus

Noh, Hyuna,Park, Soochul The Korean Society for Brain and Neural Science 2010 Experimental Neurobiology Vol.19 No.1

<P>EphA/ephrin-A mediated signaling has emerged as a key mechanism regulating axon guidance and topographic mapping, particularly in the well-characterized visual system from the retina to the superior colliculus (SC). In this study, EphA8 bacterial artificial chromosome (BAC) was manipulated to contain a floxed eGFP and human ephrin-A5 expression cassette using homologous recombination method. In the mice containing the recombinant BAC, it was shown that GFP is expressed in an anterior>posterior gradient in the SC. Furthermore, when these mice were crossed with the transgenic mice expressing Cre under the EphA8 promoter, it was evident that a GFP expression cassette was eliminated, and that human ephrin-A5 was ectopically expressed in the anterior region of the SC. This transgenic model would be useful to analyze the role of ephrin-A5 in the SC during the retinocollicular topography formation.</P>

연속 함수를 이용한 볼륨 데이터의 렌더링

노현아(Hyuna Noh),김재정(Jayjeong Kim) 한국정보과학회 2003 한국정보과학회 학술발표논문집 Vol.30 No.1B

MRI 나 CT 스캔에 의해 생성된 볼륨 데이터는 일반적으로 여러 샘플 지점에서의 이산적인 수치 데이터 일뿐 데이터 상호간의 함수적 연속성은 제공되지 않고 있다. 이러한 데이터로부터 우리가 원하는 임계값(threshold)에 의한 등가면(isosurface)을 렌더링하는 방법은 보통 Marching Cube에서처럼 많은 다각형을 생성해서 렌더링 하는 방법에 의존해 왔다. 그러나 원하는 등가면을 직접 표현할 수 있는 함수가 존재할 경우 많은 양의 다각형을 추출하고 보관해야 하는 시공간적 부담이 없게 된다. 본 논문에서는 각 Cube별로 정의되는 Tri-linear Interpolation 함수를 기반으로 하여 Interval Method 에 의한 등가면 렌더링 알고리즘을 제안한다.

미래 대학입시를 위한 정보교육 개선방안 연구

노현아 ( Hyuna Noh ),이원규 ( Wongyu Lee ) 한국컴퓨터교육학회 2016 한국컴퓨터교육학회 학술발표대회논문집 Vol.20 No.1

세계 여러 나라에서 정보교육의 중요성을 강조하고 있는 흐름에 맞도록 한국도 개선할 필요가 있다. 일본에서는 정보과목을 독립교과로 지정하여 대학입학시험에 반영하는 것을 검토함과 동시에 이를 더욱 구체화 시키기 위해 대학정보입시 전국모의시험을 매년 시행하고 있다. 이에 한국에서도 정보교육을 받은 고등학생을 대상으로 일본의 대학정보입시 전국모의시험을 측정하여 한국 고등학생의 현 위치를 알아보고자 한다.

한·일 고등학생 대상으로 `정보` 관련 문항을 통한 수준 측정 및 비교 분석

노현아 ( Hyuna Noh ),이원규 ( Wongyu Lee ) 한국컴퓨터교육학회 2016 컴퓨터교육학회 논문지 Vol.19 No.6

세계적으로 정보교육의 중요성이 가속화됨에 따라 일본은 2020년부터 대학입시 제도에서 입시 과목으로 `정보` 교과의 반영을 고려하고 있다. 일본 정보입시연구회는 2013년도부터 대학입시 수준의 `정보` 전국모의시험을 매년 실시하여 고등학생의 적절한 수준 및 변화 추이를 파악할 수 있는 데이터를 축적하고 있다. 본 연구에서는 일본에서 현재까지 시행된 전국모의시험과 동일한 문항을 한국 일반계 고등학생을 대상으로 실시하여 한국과 일본 고등학생의 수준을 비교 분석하고자 한다. 2015년 일본 대학입시 `정보` 전국모의시험을 한국과 일본 고등학생을 대상으로 실시하고 전체 평균 및 각 분야별 평균 비교 분석, 성별 분석을 통해 한국일반계 고등학생의 수준을 비교 분석하였다. 분석 결과를 통해 고등학교에서 정보교과가 사회에서 요구되는 능력을 담보할 수 있는 필수교과로 개설되고 대학입시 과목에 반영되는 등 향후 정보교육의 추진 방향을 모색할 수 있을 것으로 기대한다. As the importance of informatics education has been accentuated all around the world, Japan is considering adopting `informatics` as a subject in the university entrance examination from 2020. Under these circumstances, Informatics university entrance research group in Japan has annually conducted an `informatics` nationwide mock test since 2013 to prepare for the time when `informatics` is adopted as a subject in the university entrance exam and has accumulated the data which help understand the informatics education level of high school students and its trend. This study thus provided the Korean high school students with the questions which are the same as those from the informatics nationwide mock tests conducted in Japan so far in order to identify the education level of informatics among Korean and Japanese students. Overall mean scores and mean scores in each subject of Korean and Japanese students in the 2015 informatics nationwide mock tests were compared and analyzed and the gender analysis was conducted. These results will be expected to suggest the direction for the future informatics education such as adopting `informatics` as a subject in the university entrance exam in order to be a compulsory subject in the high school curriculum that can ensure the required skills in society.

Forecasting Korean Stock Returns with Machine Learning

Noh Hohsuk,Jang Hyuna,Yang Cheol‐Won 한국증권학회 2023 Asia-Pacific Journal of Financial Studies Vol.52 No.2

This paper aims to evaluate the predictive power of financial variables by using various machine learning methods. An analysis is conducted on data for the Korean stock market, which is representative of emerging markets, over 32 years from 1987 to 2018. The study shows that median regression is a more efficient tool than mean regression in the presence of potential heterogeneity of stocks, significantly improving performance in terms of average realized monthly return. This suggests that median regression can have better predictive performance in emerging markets where there are likely to be outliers. Additionally, a gradient boosting machine (GBM) is found to be better than a traditional linear model both in prediction accuracy and portfolio performance. The hedged return from GBM is on average 2.89% per month with an annualized Sharpe ratio of 0.93 in the median regression. The neural network (NN) is also tested and shown to perform best when the number of hidden layers is two or three. Finally, we evaluatea list of predictor variables with various measures of variable importance. Variables of risk, price trend and liquidity are found to serve as important predictors.

급성 충수염과 관련된 의료 소송

배현아(Hyuna Bae),노현(Hyun Noh),장혜영(Hye Young Jang),정구영(Koo Young Jung) 대한외과학회 2007 Annals of Surgical Treatment and Research(ASRT) Vol.72 No.3

Purpose: We wanted to describe the characteristics of the malpractice claims related to acute appendicitis and to identify medico-legal problems and potential preventability of such claims. Methods: A retrospective study was performed by reviewing the records at websites that furnishes judicial precedents. The records on closed malpractice claims involving acute appendicitis were abstracted from the files that were available for analysis. The records were reviewed and analyzed to determine the causes of the lawsuits, the preand post-operative diagnoses, the comorbid conditions of the patient, the causes of death or post-operative complications, the results of the lawsuits and the factors associated with a successful defense. Results: Twelve closed claims involving acute appendicitis were founded in the malpractice data. Two claims were Supreme Court decisions and ten were district court decisions. The causes of lawsuit were categorized as follows: delay in diagnosis or operation, mistakes during operation, inappropriate management of postoperative complications and problems related to general anesthesia. 3 claims were assigned to each of the 4 particular causes of lawsuits. The most common causes of death were abscess with peritonitis and sepsis, and ten of which resulted in indemnity payments. Conclusion: Appropriate explanation and attention in the diagnosis/progress of appendicitis, getting an informed consent from the patient, the patients’ comorbid conditions, early decision making in diagnosis/operation and proper care in the operation were critical for preventing lawsuits related to acute appendicitis.