• 대한의용생체공학회:의공학회지
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• 제21권4호
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• pp.333-338
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• 2000

본 논문에서는 T1 강조영상, T2 강조 영상 그리고 PD의 영상의 특징을 상호 보완적으로 이용한 자동적인 영상 분할법을 제안한다. 제안한 분할 알고리듬은 3단계로 이루어지는데, 첫 단계에서는 PD 영상으로부터 대뇌 마스크를 획득한 후, T1과 T2, PD의 입력 영상에 대뇌 마스크를 씌워 각각의 대뇌 영상을 추출하고, 둘째 단계에서는 대뇌 내부 조직에 해당하는 두드러진 클러스터(outstanding cluster)를 3차원 클러스터들 중에서 선택한다. 3차원 클러스터는 최적스케일 영상(optimal scale image)으로 이루어지는 3차원 공간상에서 화소가 밀집된 봉우리들을 교집합해서 생성되는 클러스터로 결정한다. 최적스케일 영상은 각 2타원 히스토그램에 스케일 스페이스 필터링을 적용시키고 그래프(graph) 구조를 검색하여 2차원 히스토그램의 모양을 가장 잘 나타내는 봉우리(peak) 영상을 최적 스케일 영상으로 선택한다. 마지막 단계에서는 앞에서 찾은 두드러진 클러스터의 중심값을 FCM 알고리듬의 초기중심 값으로 두고, FCM 알고리듬을 이용하여 대뇌 영상을 분할한다. 제안한 분할 알고리듬은 정확한 클러스터의 중심값을 계산함으로 초기 값을 영향을 많이 받는 FCM 알고리듬의 단점을 보완하였고 다중 스펙트럼 영상의 특성을 조합하여 분할에 이용함으로 단일 스펙트럼 영상만을 이용하는 방법보다 향상된 결과를 얻을 수 있었다.

• 센서학회지
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• 제19권3호
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• pp.214-220
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• 2010

Three-dimensional(3D) structure of specific DNA can be changed between two conformations under an external environmental transition such as pH and salt concentration variations. We have experimentally observed the conformational transitions of i-motif DNA using AFM cantilever bioassay. It is shown that pH change of a solvent induces the bending defleciton change of a cantilever functionalized by i-motif DNA. This indicates that cantilever bioassay enables the label-free detection of DNA structural changes upon pH change. It is implied that cantilever bioassay can be a de novo route to quantitatively understand the conformational transitions of biological molecules under environmental changes.

• 한국재료학회지
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• 제31권3호
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• pp.122-131
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• 2021

In the fabrication of joined materials between anodized aluminum alloy and polymer, the performance of the metal-polymer joining is greatly influenced by the chemical properties of the oxide film. In a previous study, the dependence of physical joining strength on the thickness, structure, pore formation, and surface roughness of films formed on aluminum alloys is investigated. In this study, we investigated the effect of silane coupling treatment on the joining strength and sealing performance between aluminum alloy and polymer. After a two-step anodization process with additional treatment by silane, the oxide film with chemically modified nanostructure is strongly bonded to the polymer through physical and chemical reactions. More specifically, after the two-step anodization with silane treatment, the oxide film has a three-dimensional (3D) nanostructure and the silane components are present in combination with hydroxyl groups up to a depth of 150 nm. Accordingly, the joining strength between the polymer and aluminum alloy increases from 29 to 35 MPa, and the helium leak performance increases from 10-2-10-4 to 10-8-10-9 Pa ㎥ s-1.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.1972-1984
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• 2013

Microtubules play an important role in intracellular transport, mobility, and particularly mitosis. Paclitaxel (Taxol$^{TM}$) and paclitaxel-like compounds have been shown to be anti-tumor agents useful for various human tumors. Paclitaxel-like compounds operate by stabilizing microtubules through interface binding at the interface between two ${\beta}$-tubulin monomers in adjacent protofilaments. In this paper we present the elucidation of the structural features of paclitaxel and paclitaxel-like compounds (e.g., epothilones) with microtubule stabilizing activities, and relate their activities to spatial and chemical features of the molecules. CATALYST program was used to generate three-dimensional quantitative structure activity relationships (3D-QSARs) resulting in 3D pharmacophore models of epothilone- and paclitaxel-derivatives. Pharmacophore models were generated from diverse conformers of these compounds resulting in a high correlation between experimental and predicted biological activities (r = 0.83 and 0.91 for epothilone and paclitaxel derivatives, respectively). On the basis of biological activities of the training sets, five- and four-feature pharmacophore hypotheses were generated in the epothilone and paclitaxel series. The validation of generated hypotheses was achieved by using twelve epothilones and ten paclitaxels, respectively, which are not in the training sets. The clustering (grouping) and merging techniques were used in order to supplement spatial restrictions of each of hypothesis and to develop more comprehensive models. This approach may be of use in developing novel inhibitor candidates as well as contributing a better understanding of structural characters of many compounds useful as anticancer agents targeting microtubules.

• Journal of Applied Biological Chemistry
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• 제53권4호
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• pp.225-231
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• 2010

기질분자로서 polyhydroxy 치환된 2-phenyl-l,4-benzopyrone 유도체(Flavones)(1-25)들의 hydroxyl 치환기($R_1-R_9$)가 변화함에 따른 Tyrosinase(PDB ID: oxy-form; 1WX2)에 대한 저해활성을 이해하기 위하여 분자도킹과 3차원적인 정량적 구조활성관계 (3D-QSARs: CoMFA 및 CoMSIA)가 연구되었다. 그 결과, 통계적으로 CoMFA 1 및 CoMSIA 1 모델이 가장 양호한 3D-QSARs 모델이었다. 또한, 순차 혼합화 분석결과로부터 CoMSIA 1 모델($dq^2'/dr_{yy'}^2$=1.009 및 $q^2$=0.511)이 우연상관성에 저촉되지 않는 최적화 모텔이었으며 최적화된 CoMSIA 1 모델의 tyrosinase에 대한 저해활성은 기질분자의 정전기장(51.4%)에 의존적이었다. Tyrosinase의 반응점에 대한 3D-QSAR 모델의 등고도는 수용체로서 tyrosinase과 저해제로서 2-phenyl-l,4-benzopyrone 기질분자 사이의 새로운 상호작용 관계를 이해하는 계기가 되었다. 그러므로 이 결과들은 새로운 잠재적인 tyrosinase 저해제의 최적화에 적용될 수 있을 것이다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.141-144
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• 1997

Femoral neck anteversion is the angle between the neck and the knee axis projected on a plane perpendicular to the longitudinal axis. Conventional methods that use cross-sectional Computed Tomography(CT) images to estimate femoral anteversion have several problems because of the complex 3D structure of the femur. These are the ambiguity of defining the longitudinal axis, the femoral neck axis and condylar line, and the dependence on patient positioning. Especially the femoral neck axis that is known as a major source of error is hard to determine from a single or multiple 2D transverse images. So we developed a new method for measuring femoral anteversion by 3D modeling method. In this method, femoral head is modeled as a sphere. The center of femoral neck is the mid-point of the 2D reconstructed oblique image in the femoral neck part. Then neck axis is a line connecting foregoing two centers. We model the longitude of femur as a cylinder, and the long axis is defined from the fitted cylinder. The knee axis which is tangent to the back of the femoral condyles is easily determined by table-top method. By the definition of femoral anteversion, the femoral anteversion is easily calculated from this model.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.159-160
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• 1998

Results of chemistry and biological activity of many years indicate that plants belonging to the Isodon genus are rich in ent-kaurane diterpenoids, which have been revealed to possess biological activities such as antitumor, antibacterial and antiinflammatory effects. In continuation of our research on diterpenoids in medicinal plants of this genus, the acetone extract from the leaves of I. xerophilus, which is a plant native to Yunnan province of China, showed potent antitumor activity against K562. After partition, the most active EtOAc part was studied. Four new diterpenoids named xerophilusin A(l), B(2), C(3), D(4), and eight known compounds including macrocalin B(5) and rabdorosthomin A(6) were isolated, whose structures were elucidated through a series of one- and two-dimensional NMR techniques(DEPT, COSY, HMQC, HMBC and ROESY experiments). Among them, compound 1, 2 and 5 had two unique epoxy units formed by two ether bridges from C-20 to C-7, C-14. Up to now, there are four compounds having such an peculiar structure besides these three compounds. Compound 3 and 4 were two of the few examples possessing $1{\beta}$ substitutes. All the diterpenoid compounds were subjected to the antitumor screening. It is interesting that only xerophilusin A(l), B(2) and macrocalin(5) exhibited significant antitumor activity against K562 by the method of MTT($IC_{50}$ were listed in Table 1.). The results inspired us to infer that the unique ether bridges from C-20 to C-7, C-14 possibly played an important role in the antitumor activity.

• 대한의용생체공학회:의공학회지
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• 제30권2호
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• pp.135-141
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• 2009

Purpose: The aim of present study is to evaluate a possibility of clinical application for the effect of low intensity ultrasound stimulation (LIUS) in mechanical characteristics of bone on osteoporotic fractures prevention. Materials and Methods: Eight virgin ICR mice (14 weeks old, approximate weight 25g) were ovariectomized (OVX) to induce osteoporosis. The right hind limbs were then stimulated with LIDS (US Group), whereas left hind limbs were not stimulated (CON Group). Both hind limbs of all mice were scanned by in-vivo micro-CT to acquire two-dimensional (2D) images at 0 week before stimulation and 3 weeks and 6 weeks after stimulation. Three-dimensional (3D) finite element (FE) models generated by scanned 2D images were used to determine quantitatively the effect of LIUS on strength related to bone structure. Additionally, distributions of Hounsfield units and elastic moduli, which are related to the bone quality, for the bones in the US and CON groups were determined to analyze quantitatively a degree of improvement of bone qualities achieved by LIUS. Results: The result of FE analysis showed that the structural strength in US Group was significantly increased over time (p<0.05), while that in CON Group was statistically constant over time (p>0.05). High values of Hounsfield units obtained from voxels on micro-CT images and high values of elastic moduli converted from the Hounsfield units were dominantly appeared in US Group compared with those in CON Group. Conclusion: These finding indicated that LIUS would improve the mechanical characteristics of osteoporotic bone via the effects of bone structure (bone strength) and quality (Hounsfield unit and elastic modulus). Therefore, the LIUS may decrease effectively the risk of osteoporotic fracture in clinics.

• 농약과학회지
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• 제9권2호
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• pp.140-145
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• 2005

정량적 구조 활성관계 모델링은 물리적인 성질과 생물학적 활성이 관계 있다는 것을 전제로 한다. 그러나, 퍼센트 활성과 같은 데이터들은 모델링에 많이 활용되지 않았다. 이것의 중요한 이유중의 하나는 이러한 값들이 정량적이 아니고 정성적인 데에 있다. 본 연구에서는 분자모델링에 퍼센트활성 데이터를 활용하기 위하여 데이터 값들을 2개의 계층으로 분류하고 CoMFA(비교분자장)를 판별함수로 활용하였다. 즉, 베타-케토아세트아닐라이드 유도체들의 토마토 역병균에 대한 항균력 시험의 퍼센트 활성 데이터를, 한 계층은 활성이 있는 것, 다른 계층은 활성이 없는 것으로 나누었다. 특히, CoMFA를 활용함으로써 화학적인 이해에 중요한 3차원적인 정보를 얻을 수 있었다. 이 모델은 주어진 데이타를 98%의 정확도로 설명하였으며, LOO 검증을 해본 결과 예측력은 약 69% 정도였다 이 결과는 활성 데이터를 근사적으로 2개의 계급으로 나누고 CoMFA를 활용하는 방식이 구조활성관계를 이해하고 화합물 유도체를 합성하는데 활용될 수 있음을 보여준다.

• Journal of Applied Biological Chemistry
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• 제53권2호
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• pp.99-104
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• 2010

3차원적인 정량적 구조-활성상관(3D-QSAR: 비교분자 유사성지수분석(CoMSIA) 및 비교분자장분석(CoMFA)) 기법에 기초하여 4-Methyl-2H-benzopyran-2-one 유도체들(1-23)의 항산화활성에 관한 benzo 고리상 치환기($R_1-R_4$)들의 영향을 정량적으로 검토하였다. CoMSIA 모델은 CoMFA 모델보다 통계적으로 양호하였으며 최적화된 CoMSIA 2 모델의 예측성($q^2$=0.700)과 상관성($r^2$=0.979)이 가장 양호하였다. 항산화 활성에 관한 CoMSIA 2 모델의 기여비율(%)은 수소결합 주게장(HD) 43.5%, 정전기장(E) 41.8% 및 입체장(S) 14.7%로 정전기장과 H-결합 주게장이 항산화활성에 가장 큰 영향을 미치는 요소이었다. CoMSIA 등고도 분석결과, benzo 고리상에 양하전을 선호하며, 그리고 H-결합주게가 아닌 치환기($R_1-R_4$)들이 항산화활성을 증가시킬 것으로 예상되었다.