111 research outputs found
Cerebral Blood Volume Calculated by Dynamic Susceptibility Contrast-Enhanced Perfusion MR Imaging: Preliminary Correlation Study with Glioblastoma Genetic Profiles
No full textPurpose: To evaluate the usefulness of dynamic susceptibility contrast (DSC) enhanced perfusion MR imaging in predicting
major genetic alterations in glioblastomas.
Materials and Methods: Twenty-five patients (M:F = 13:12, mean age: 52.1615.2 years) with pathologically proven
glioblastoma who underwent DSC MR imaging before surgery were included. On DSC MR imaging, the normalized relative
tumor blood volume (nTBV) of the enhancing solid portion of each tumor was calculated by using dedicated software
(Nordic TumorEX, NordicNeuroLab, Bergen, Norway) that enabled semi-automatic segmentation for each tumor. Five major
glioblastoma genetic alterations (epidermal growth factor receptor (EGFR), phosphatase and tensin homologue (PTEN), Ki-
67, O6-methylguanine-DNA methyltransferase (MGMT) and p53) were confirmed by immunohistochemistry and analyzed
for correlation with the nTBV of each tumor. Statistical analysis was performed using the unpaired Student t test, ROC
(receiver operating characteristic) curve analysis and Pearson correlation analysis.
Results: The nTBVs of the MGMT methylation-negative group (mean 9.567.5) were significantly higher than those of the
MGMT methylation-positive group (mean 5.461.8) (p = .046). In the analysis of EGFR expression-positive group, the nTBVs of
the subgroup with loss of PTEN gene expression (mean: 10.368.1) were also significantly higher than those of the subgroup
without loss of PTEN gene expression (mean: 5.662.3) (p = .046). Ki-67 labeling index indicated significant positive
correlation with the nTBV of the tumor (p = .01).
Conclusion: We found that glioblastomas with aggressive genetic alterations tended to have a high nTBV in the present
study. Thus, we believe that DSC-enhanced perfusion MR imaging could be helpful in predicting genetic alterations that are
crucial in predicting the prognosis of and selecting tailored treatment for glioblastoma patients.1011Nsciescopu
갑상선 결절의 경피적 세침 흡인물에 대한 핵 자기 공명 대사체학적 성분 분석: 갑상선 유두암 진단 방법으로서의 가능성 평가
No full text학위논문 (박사)-- 서울대학교 대학원 : 의학과, 2014. 2. 김현진.Introduction: Cytopathologic analysis of fine needle aspiration biopsy (FNAB) specimens is the standard diagnostic test for thyroid nodules. However, its accuracy and adequacy has been reported to be limited for the diagnosis of thyroid nodules. The purpose of this study is to present the differences in the metabolomic profiles of malignant (papillary thyroid carcinoma [PTC]) and benign thyroid nodules using metabolomic analysis (nuclear magnetic resonance [NMR]) of FNAB specimens of thyroid nodules and to evaluate the potential of the metabolomic approach (NMR) as an ancillary method for diagnosing PTC.
Methods: In total, 230 samples from patients with thyroid nodules were collected by ultrasonography-guided percutaneous FNABamong them, 35 samples diagnosed as malignant (PTC) and 69 samples diagnosed as benign follicular nodules on conventional cytopathologic analysis were spectroscopically analyzed using 1.7 mm tube NMR. Metabolomic profiles were statistically generated based on the NMR results, and their correlation with conventional cytopathologic diagnoses from the same samples were assessed to determine the feasibility of using these profiles as a diagnostic tool for thyroid nodules. Furthermore, we analyzed the correlation between the metabolomic profiles of surgically confirmed 25 PTC samples and clinicopathologic factors such as tumor multiplicity, T stage, N stage, and BRAF mutation status.
Results: Benign nodules and PTCs could be distinguished according to the different relative concentrations of several metabolites. The citrate (2.6 ppm), glutamate (2.0 ppm), and glutamine (2.1 ppm) levels in benign samples were greater than those in PTC samples and the lactate (1.3 ppm) and choline (3.2 ppm) levels in PTC samples were greater than those in benign samples. Receiver operating characteristic (ROC) curve analysis indicated that seven metabolites could serve as discriminators (area under the ROC curve value, 0.64-0.85), of which citrate was the most significant discriminator.
However, in PTC subgroup analysis, we did not observe a significant correlation between clinicopathologic factors and metabolomic profiles.
Conclusions: This study results indicate the potential of the metabolomic approach (NMR) as an ancillary method for diagnosing PTC using FNAB specimens of thyroid nodules.Abstract i
Contents iv
List of figures and tables v
List of abbreviations. vii
Introduction 1
Materials and Methods 4
Results 8
Discussion 19
References 26
Abstract in Korean 33Docto
Design of bimetallic nanoparticles
No full textThis work was supported by Korean Research Foundation Grant(KRF-2003-003-D00087). The author(S.J.Cho) acknowledged the generous permission to use the synchortron radiation at the Pohang Accelerator Laboratory
Flame-made amorphous solid acids with tunable acidity for the aqueous conversion of glucose to levulinic acid
No full textSolid acids of amorphous silica-alumina (a-SA) and amorphous silica-alumina-phosphate (a-SAPO) were prepared by flame spray pyrolysis (FSP). Careful tuning of the acidity of the solid acids was enabled by capitalizing on the advantage of FSP in preserving the metal stoichiometry (i.e., Si, Al, P) in the product nanoparticles. Although the amount of acids on these non-porous solid acids is an order of magnitude lower than the well-recognized strong acidic ZSM-5 zeolite, both exhibit comparable acid strengths. The a-SA and a-SAPO were characterized by a mixture of Brønsted (B) and Lewis (L) acids, and the B/L ratios were composition-tunable. The highest B/L ratios were recorded for a-SA (Al/(Al + Si) = 0.4) and a-SAPO (Si/(P + Si) = 0.25), giving the highest yields of levulinic acid (≥40% carbon yield) from the conversion of glucose in the aqueous phase without requiring the addition of liquid acids or metal halides. Under the same conditions, the almost exclusive Brønsted acid ZSM-5 yielded only 17% levulinic acid. The FSP-made solid acid catalyst exhibited good reusability over at least 4 consecutive runs.ChemE/Catalysis Engineerin
Cerebral Blood Volume Analysis in Glioblastomas Using Dynamic Susceptibility Contrast-Enhanced Perfusion MRI: A Comparison of Manual and Semiautomatic Segmentation Methods
No full textPurpose: To compare the reproducibilities of manual and semiautomatic segmentation method for the measurement of
normalized cerebral blood volume (nCBV) using dynamic susceptibility contrast-enhanced (DSC) perfusion MR imaging in
glioblastomas.
Materials and Methods: Twenty-two patients (11 male, 11 female; 27 tumors) with histologically confirmed glioblastoma
(WHO grade IV) were examined with conventional MR imaging and DSC imaging at 3T before surgery or biopsy. Then nCBV
(means and standard deviations) in each mass was measured using two DSC MR perfusion analysis methods including
manual and semiautomatic segmentation method, in which contrast-enhanced (CE)-T1WI and T2WI were used as structural
imaging. Intraobserver and interobserver reproducibility were assessed according to each perfusion analysis method or
each structural imaging. Interclass correlation coefficient (ICC), Bland-Altman plot, and coefficient of variation (CV) were
used to evaluate reproducibility.
Results: Intraobserver reproducibilities on CE-T1WI and T2WI were ICC of 0.74–0.89 and CV of 20.39–36.83% in manual
segmentation method, and ICC of 0.95–0.99 and CV of 8.53–16.19% in semiautomatic segmentation method, repectively.
Interobserver reproducibilites on CE-T1WI and T2WI were ICC of 0.86–0.94 and CV of 19.67–35.15% in manual segmentation
method, and ICC of 0.74–1.0 and CV of 5.48–49.38% in semiautomatic segmentation method, respectively. Bland-Altman
plots showed a good correlation with ICC or CV in each method. The semiautomatic segmentation method showed higher
intraobserver and interobserver reproducibilities at CE-T1WI-based study than other methods.
Conclusion: The best reproducibility was found using the semiautomatic segmentation method based on CE-T1WI for
structural imaging in the measurement of the nCBV of glioblastomas.141611sciescopu
High-throughput chemical screening to discover new modulators of microRNA expression in living cells by using graphene-based biosensor
No full textMicroRNAs (miRNAs) are important regulatory RNAs that control gene expression in various biological processes. Therefore, control over the disease-related miRNA expression is important both for basic research and for a new class of therapeutic modality to treat serious diseases such as cancer. Here, we present a high-throughput screening strategy to identify small molecules that modulate miRNA expression in living cells. The screen enables simultaneous monitoring of the phenotypic cellular changes associated with the miRNA expression by measuring quantitative fluorescent signals corresponding to target miRNA level in living cells based on a novel biosensor composed of peptide nucleic acid and nano-sized graphene oxide. In this study, the biosensor based cellular screening of 967 compounds (including FDA-approved drugs, enzyme inhibitors, agonists, and antagonists) in cells identified four different classes of small molecules consisting of (i) 70 compounds that suppress both miRNA-21 (miR-21) expression and cell proliferation, (ii) 65 compounds that enhance miR-21 expression and reduce cell proliferation, (iii) 2 compounds that suppress miR-21 expression and increase cell proliferation, and (iv) 21 compounds that enhance both miR-21 expression and cell proliferation. We further investigated the hit compounds to correlate cell morphology changes and cell migration ability with decreased expression of miR-21 © Te Author(s) 201
Hyperintense Thyroid Incidentaloma on Time of Flight Magnetic Resonance Angiography
No full textBackground: The purpose of this study was to evaluate the clinical significance of thyroid incidentaloma with hypersignal intensity on the time of flight magnetic resonance (TOF-MR) angiography and correlation with ultrasound (US).Methods: We retrospectively reviewed 3,505 non-contrast TOF-MR angiography performed at our institution between September 2014 and May 2017. Two radiologists correlated the thyroid incidentalomas detected on TOF-MR angiography with US features that were obtained within a three-month interval between MR and US examinations in consensus.Results: The prevalence of hyperintense thyroid nodules incidentally detected by TOF-MR angiography was 1.2% (43/3,505 patients). Among these, 35 people (77.8%) underwent US examinations, and a total of 45 hyperintense thyroid nodules were detected by US studies. Of these 45 nodules, more than 70% were categorized as benign on US exams. Fine needle aspiration was performed on nine nodules according to indications recommended by the Korean Society of Thyroid Radiology. All except one high-suspicion thyroid nodule were confirmed as benign (Bethesda 2) on cytologic examination. The high-suspicion nodule on US showed a nondiagnostic result (Bethesda 1). However, this nodule collapsed after aspiration of thick colloid.Conclusions: Our study demonstrated that the most hyperintense thyroid nodules detected on TOF-MR angiography were benign. Therefore, if a hyperintense incidentaloma is found on TOF-MR angiography, the thyroid nodule is more likely to be benign. We believe that these findings could offer additional information for further clinical management
Oxygen activation on the interface between Pt nanoparticles and mesoporous defective TiO2 during CO oxidation
No full text© 2019 Author(s).Platinum-based heterogeneous catalysts are mostly used in various commercial chemical processes because of their high catalytic activity, influenced by the metal/oxide interaction. To design rational catalysts with high performance, it is crucial to understand the relationship between the metal-oxide interface and the reaction pathway. Here, we investigate the role of oxygen defect sites in the reaction mechanism for CO oxidation using Pt nanoparticles supported on mesoporous TiO2 catalysts with oxygen defects. We show an intrinsic correlation between the catalytic reactivity and the local properties of titania with oxygen defects (i.e., Ti3+ sites). In situ infrared spectroscopy observations of the Pt/mesoporous TiO2-x catalyst indicate that an oxygen molecule bond can be activated at the perimeter between the Pt and an oxygen vacancy in TiO2 by neighboring CO molecules on the Pt surface before CO oxidation begins. The proposed reaction pathways for O2 activation at the Pt/TiO2-x interface based on density functional theory confirm our experimental findings. We suggest that this provides valuable insight into the intrinsic origin of the metal/support interaction influenced by the presence of oxygen vacancies, which clarifies the pivotal role played by the support11sciescopu
Ultrafast charge transfer coupled with lattice phonons in two-dimensional covalent organic frameworks
No full text© 2019, The Author(s). Covalent organic frameworks (COFs) have emerged as a promising light-harvesting module for artificial photosynthesis and photovoltaics. For efficient generation of free charge carriers, the donor–acceptor (D-A) conjugation has been adopted for two-dimensional (2D) COFs recently. In the 2D D-A COFs, photoexcitation would generate a polaron pair, which is a precursor to free charge carriers and has lower binding energy than an exciton. Although the character of the primary excitation species is a key factor in determining optoelectronic properties of a material, excited-state dynamics leading to the creation of a polaron pair have not been investigated yet. Here, we investigate the dynamics of photogenerated charge carriers in 2D D-A COFs by combining femtosecond optical spectroscopy and non-adiabatic molecular dynamics simulation. From this investigation, we elucidate that the polaron pair is formed through ultrafast intra-layer hole transfer coupled with coherent vibrations of the 2D lattice, suggesting a mechanism of phonon-assisted charge transfe
A Comparison Test on the Potential Utility between Author Profiling Analysis(APA) and Author Co-Citation Analysis(ACA)
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