Showing papers by "Yonsei University published in 2011"

Exchange-coupled magnetic nanoparticles for efficient heat induction

Abstract: The properties of core–shell nanoparticles can be tuned so that they efficiently convert radiation into heat, leading to therapeutic results that are competitive with commercial drug treatments.

Thyroid Imaging Reporting and Data System for US Features of Nodules: A Step in Establishing Better Stratification of Cancer Risk

Abstract: Risk stratification of thyroid malignancy by using the number of suspicious US features allows for a practical and convenient thyroid imaging reporting and data system.

Fluorescent and luminescent probes for detection of reactive oxygen and nitrogen species

Abstract: Oxidative and nitrosative stress induced by ROS/RNS play crucial roles in a wide range of physiological processes and are also implicated in various diseases, including cancer and neurodegenerative disorders. Sensitive and selective methods for the detection of ROS/RNS based on fluorescent and luminescent probes are of great use in monitoring the in vivo production of these species and elucidating their biological functions. This critical review highlights recent advances that have been made in the development of fluorescent and luminescent probes employed to monitor various ROS/RNS (132 references).

Sapiens: A Brief History of Humankind

Abstract: 100,000 years ago, at least six human species inhabited the earth Today there is just one Us Homo sapiens How did our species succeed in the battle for dominance? Why did our foraging ancestors come together to create cities and kingdoms? How did we come to believe in gods, nations and human rights; to trust money, books and laws; and to be enslaved by bureaucracy, timetables and consumerism? And what will our world be like in the millennia to come? In Sapiens, Dr Yuval Noah Harari spans the whole of human history, from the very first humans to walk the earth to the radical - and sometimes devastating - breakthroughs of the Cognitive, Agricultural and Scientific Revolutions Drawing on insights from biology, anthropology, palaeontology and economics, he explores how the currents of history have shaped our human societies, the animals and plants around us, and even our personalities Have we become happier as history has unfolded? Can we ever free our behaviour from the heritage of our ancestors? And what, if anything, can we do to influence the course of the centuries to come? Bold, wide-ranging and provocative, Sapiens challenges everything we thought we knew about being human: our thoughts, our actions, our powerand our future "Here is a simple reason why Sapiens has risen explosively to the ranks of an international bestseller It tackles the biggest questions of history and of the modern world, and it is written in unforgettably vivid language You will love it!" (Jared Diamond)

Drosophila Microbiome Modulates Host Developmental and Metabolic Homeostasis via Insulin Signaling

Abstract: The symbiotic microbiota profoundly affect many aspects of host physiology; however, the molecular mechanisms underlying host-microbe cross-talk are largely unknown. Here, we show that the pyrroloquinoline quinone–dependent alcohol dehydrogenase (PQQ-ADH) activity of a commensal bacterium, Acetobacter pomorum, modulates insulin/insulin-like growth factor signaling (IIS) in Drosophila to regulate host homeostatic programs controlling developmental rate, body size, energy metabolism, and intestinal stem cell activity. Germ-free animals monoassociated with PQQ-ADH mutant bacteria displayed severe deregulation of developmental and metabolic homeostasis. Importantly, these defects were reversed by enhancing host IIS or by supplementing the diet with acetic acid, the metabolic product of PQQ-ADH.

Prioritizing candidate disease genes by network-based boosting of genome-wide association data

Abstract: Network "guilt by association" (GBA) is a proven approach for identifying novel disease genes based on the observation that similar mutational phenotypes arise from functionally related genes. In principle, this approach could account even for nonadditive genetic interactions, which underlie the synergistic combinations of mutations often linked to complex diseases. Here, we analyze a large-scale, human gene functional interaction network (dubbed HumanNet). We show that candidate disease genes can be effectively identified by GBA in cross-validated tests using label propagation algorithms related to Google's PageRank. However, GBA has been shown to work poorly in genome-wide association studies (GWAS), where many genes are somewhat implicated, but few are known with very high certainty. Here, we resolve this by explicitly modeling the uncertainty of the associations and incorporating the uncertainty for the seed set into the GBA framework. We observe a significant boost in the power to detect validated candidate genes for Crohn's disease and type 2 diabetes by comparing our predictions to results from follow-up meta-analyses, with incorporation of the network serving to highlight the JAK-STAT pathway and associated adaptors GRB2/SHC1 in Crohn's disease and BACH2 in type 2 diabetes. Consideration of the network during GWAS thus conveys some of the benefits of enrolling more participants in the GWAS study. More generally, we demonstrate that a functional network of human genes provides a valuable statistical framework for prioritizing candidate disease genes, both for candidate gene-based and GWAS-based studies.

Theranostic magnetic nanoparticles

Abstract: Early detection and treatment of disease is the most important component of a favorable prognosis. Biomedical researchers have thus invested tremendous effort in improving imaging techniques and treatment methods. Over the past decade, concepts and tools derived from nanotechnology have been applied to overcome the problems of conventional techniques for advanced diagnosis and therapy. In particular, advances in nanoparticle technology have created new paradigms for theranostics, which is defined as the combination of therapeutic and diagnostic agents within a single platform. In this Account, we examine the potential advantages and opportunities afforded by magnetic nanoparticles as platform materials for theranostics.We begin with a brief overview of relevant magnetic parameters, such as saturation magnetization, coercivity, and magnetocrystalline anisotropy. Understanding the interplay of these parameters is critical for optimizing magnetic characteristics needed for effective imaging and therapeutics,...

Randomized trial of stents versus bypass surgery for left main coronary artery disease.

Abstract: Background Percutaneous coronary intervention (PCI) is increasingly used to treat unprotected left main coronary artery stenosis, although coronary-artery bypass grafting (CABG) has been considered to be the treatment of choice. Methods We randomly assigned patients with unprotected left main coronary artery stenosis to undergo CABG (300 patients) or PCI with sirolimus-eluting stents (300 patients). Using a wide margin for noninferiority, we compared the groups with respect to the primary composite end point of major adverse cardiac or cerebrovascular events (death from any cause, myocardial infarction, stroke, or ischemia-driven target-vessel revascularization) at 1 year. Event rates at 2 years were also compared between the two groups. Results The primary end point occurred in 26 patients assigned to PCI as compared with 20 patients assigned to CABG (cumulative event rate, 8.7% vs. 6.7%; absolute risk difference, 2.0 percentage points; 95% confidence interval [CI], −1.6 to 5.6; P=0.01 for noninferiority...

Minimum information about a marker gene sequence (MIMARKS) and minimum information about any (x) sequence (MIxS) specifications.

Abstract: Here we present a standard developed by the Genomic Standards Consortium (GSC) for reporting marker gene sequences—the minimum information about a marker gene sequence (MIMARKS). We also introduce a system for describing the environment from which a biological sample originates. The ‘environmental packages’ apply to any genome sequence of known origin and can be used in combination with MIMARKS and other GSC checklists. Finally, to establish a unified standard for describing sequence data and to provide a single point of entry for the scientific community to access and learn about GSC checklists, we present the minimum information about any (x) sequence (MIxS). Adoption of MIxS will enhance our ability to analyze natural genetic diversity documented by massive DNA sequencing efforts from myriad ecosystems in our ever-changing biosphere.

DICER1 deficit induces Alu RNA toxicity in age-related macular degeneration

Abstract: Geographic atrophy (GA), an untreatable advanced form of age-related macular degeneration, results from retinal pigmented epithelium (RPE) cell degeneration. Here we show that the microRNA (miRNA)-processing enzyme DICER1 is reduced in the RPE of humans with GA, and that conditional ablation of Dicer1, but not seven other miRNA-processing enzymes, induces RPE degeneration in mice. DICER1 knockdown induces accumulation of Alu RNA in human RPE cells and Alu-like B1 and B2 RNAs in mouse RPE. Alu RNA is increased in the RPE of humans with GA, and this pathogenic RNA induces human RPE cytotoxicity and RPE degeneration in mice. Antisense oligonucleotides targeting Alu/B1/B2 RNAs prevent DICER1 depletion-induced RPE degeneration despite global miRNA downregulation. DICER1 degrades Alu RNA, and this digested Alu RNA cannot induce RPE degeneration in mice. These findings reveal a miRNA-independent cell survival function for DICER1 involving retrotransposon transcript degradation, show that Alu RNA can directly cause human pathology, and identify new targets for a major cause of blindness.

Drosophila microbiome modulates host developmental and metabolic homeostasis via insulin signaling

Abstract: The symbiotic microbiota profoundly affect many aspects of host physiology; however, the molecular mechanisms underlying host-microbe cross-talk are largely unknown. Here, we show that the pyrroloquinoline quinone–dependent alcohol dehydrogenase (PQQ-ADH) activity of a commensal bacterium, Acetobacter pomorum, modulates insulin/insulin-like growth factor signaling (IIS) in Drosophila to regulate host homeostatic programs controlling developmental rate, body size, energy metabolism, and intestinal stem cell activity. Germ-free animals monoassociated with PQQ-ADH mutant bacteria displayed severe deregulation of developmental and metabolic homeostasis. Importantly, these defects were reversed by enhancing host IIS or by supplementing the diet with acetic acid, the metabolic product of PQQ-ADH.

Capacity Enhancement Using an Interference Limited Area for Device-to-Device Uplink Underlaying Cellular Networks

Abstract: A new interference management strategy is proposed to enhance the overall capacity of cellular networks (CNs) and device-to-device (D2D) systems. We consider M out of K cellular user equipments (CUEs) and one D2D pair exploiting the same resources in the uplink (UL) period under the assumption of M multiple antennas at the base station (BS). First, we use the conventional mechanism which limits the maximum transmit power of the D2D transmitter so as not to generate harmful interference from D2D systems to CNs. Second, we propose a δD-interference limited area (ILA) control scheme to manage interference from CNs to D2D systems. The method does not allow the coexistence (i.e., use of the same resources) of CUEs and a D2D pair if the CUEs are located in the δD-ILA defined as the area in which the interference to signal ratio (ISR) at the D2D receiver is greater than the predetermined threshold, δD. Next, we analyze the coverage of the δD-ILA and derive the lower bound of the ergodic capacity as a closed form. Numerical results show that the δD-ILA based D2D gain is much greater than the conventional D2D gain, whereas the capacity loss to the CNs caused by using the δD-ILA is negligibly small.

Cohesive Zone Models: A Critical Review of Traction-Separation Relationships Across Fracture Surfaces

Abstract: One of the fundamental aspects in cohesive zone modeling is the definition of the traction-separation relationship across fracture surfaces, which approximates the nonlinear fracture process. Cohesive traction-separation relationships may be classified as either nonpotential-based models or potential-based models. Potential-based models are of special interest in the present review article. Several potential-based models display limitations, especially for mixed-mode problems, because of the boundary conditions associated with cohesive fracture. In addition, this paper shows that most effective displacement-based models can be formulated under a single framework. These models lead to positive stiffness under certain separation paths, contrary to general cohesive fracture phenomena wherein the increase of separation generally results in the decrease of failure resistance across the fracture surface (i.e., negative stiffness). To this end, the constitutive relationship of mixed-mode cohesive fracture should be selected with great caution.

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at root s(NN)=2.76 TeV

Abstract: The centrality dependence of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at root s(NN) = 2: 76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor of 2 from peripheral (70%-80%) to central (0%-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.

Artificial receptors for the recognition of phosphorylated molecules

Abstract: Artificial Receptors for the Recognition of Phosphorylated Molecules Amanda E. Hargrove, Sonia Nieto, Tianzhi Zhang, Jonathan L. Sessler,* and Eric V. Anslyn* Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, United States Universidad de Zaragoza, Zaragoza, Spain Henkel Corporation, Rocky Hill, Connecticut 06067 Department of Chemistry, Yonsei University, Seoul, 120-749 Korea

Precise manipulation of chromosomes in vivo enables genome-wide codon replacement.

Abstract: We present genome engineering technologies that are capable of fundamentally reengineering genomes from the nucleotide to the megabase scale We used multiplex automated genome engineering (MAGE) to site-specifically replace all 314 TAG stop codons with synonymous TAA codons in parallel across 32 Escherichia coli strains This approach allowed us to measure individual recombination frequencies, confirm viability for each modification, and identify associated phenotypes We developed hierarchical conjugative assembly genome engineering (CAGE) to merge these sets of codon modifications into genomes with 80 precise changes, which demonstrate that these synonymous codon substitutions can be combined into higher-order strains without synthetic lethal effects Our methods treat the chromosome as both an editable and an evolvable template, permitting the exploration of vast genetic landscapes

Risk estimation for hepatocellular carcinoma in chronic hepatitis B (REACH-B): development and validation of a predictive score

Abstract: Summary Background Therapy for chronic hepatitis B reduces the risk of progressing to hepatocellular carcinoma (HCC); however, there is no suitable and accurate means to assess risk. This study aimed to develop and validate a simple scoring system to predict HCC risk in patients with chronic hepatitis B. Methods The development cohort consisted of 3584 patients without cirrhosis from the community-based Taiwanese REVEAL-HBV study (of whom 131 developed HCC during follow-up), and a validation cohort of 1505 patients from three hospitals in Hong Kong and South Korea (of whom 111 developed HCC during follow-up). We used Cox multivariate proportional hazards model to predict risk of HCC at 3, 5, and 10 years. Variables included in the risk score were sex, age, serum alanine aminotransferase concentration, HBeAg status, and serum HBV DNA level. We calculated the area under receiver operating curve (AUROC) and calibration of predicted and observed HCC risk. Findings A 17-point risk score was developed, with HCC risk ranging from 0·0% to 23·6% at 3 years, 0·0% to 47·4% at 5 years, and 0·0% to 81·6% at 10 years for patients with the lowest and highest HCC risk, respectively. AUROCs to predict risk were 0·811 (95% CI 0·790–0·831) at 3 years, 0·796 (0·775–0·816) at 5 years, and 0·769 (0·747–0·790) at 10 years in the validation cohort, and 0·902 (0·884–0·918), 0·783 (0·759–0·806), and 0·806 (0·783–0·828), respectively, after exclusion of 277 patients in the validation cohort with cirrhosis. Predicted risk was well calibrated with Kaplan-Meier observed HCC risk. Interpretation A simple-to-use risk score that uses baseline clinical variables was developed and validated. The score accurately estimates the risk of developing HCC at 3, 5, and 10 years in patients with chronic hepatitis B. Clinicians can use this score to assess risk of HCC in patients with chronic hepatitis B and subsequently make evidence-based decisions about their clinical management. Funding The Academia Sinica; the National Health Research Institute, Taiwan; and Bristol-Myers Squibb.

Outage Probability of Cognitive Relay Networks with Interference Constraints

Abstract: This paper evaluates the outage probability of cognitive relay networks with cooperation between secondary users based on the underlay approach, while adhering to the interference constraint on the primary user, i.e., the limited amount of interference which the primary user can tolerate. A relay selection criterion, suitable for cognitive relay networks, is provided, and using it, we derive the outage probability. It is shown that the outage probability of cognitive relay networks is higher than that of conventional relay networks due to the interference constraint, and we quantify the increase. In addition, the outage probability is affected by the distance ratio of the interference link (between the secondary transmitter and the primary receiver) to the relaying link (between the secondary transmitter and the secondary receiver). We also prove that cognitive relay networks achieve the same full selection diversity order as conventional relay networks, and that the decrease in outage probability achieved by increasing the selection diversity (the number of relays) is not less than that in conventional relay networks.

A systematic review of hepatitis C virus epidemiology in Asia, Australia and Egypt

Abstract: Background: The hepatitis C pandemic has been systematically studied and characterized in North America and Europe, but this important public health problem has not received equivalent attention in other regions. Aim: The objective of this systematic review was to characterize hepatitis C virus (HCV) epidemiology in selected countries of Asia, Australia and Egypt, i.e. in a geographical area inhabited by over 40% of the global population. Methodology: Data references were identified through indexed journals and non-indexed sources. In this work, 7770 articles were reviewed and 690 were selected based on their relevance. Results: We estimated that 49.3‐64.0 million adults in Asia, Australia and Egypt are anti-HCV positive. China alone has more HCV infections than all of Europe or the Americas. While most countries had prevalence rates from 1 to 2% we documented several with relatively high prevalence rates, including Egypt (15%), Pakistan (4.7%) and Taiwan (4.4%). Nosocomial infection, blood transfusion (before screening) and injection drug use were identified as common risk factors in the region. Genotype 1 was common in Australia, China, Taiwan and other countries in North Asia, while genotype 6 was found in Vietnam and other Southeast Asian countries. In India and Pakistan genotype 3 was predominant, while genotype 4w as found in Middle Eastern countries such as Egypt, Saudi Arabia and Syria. Conclusion: We recommend implementation of surveillance systems to guide effective public health policy that may lead to the eventual curtailment of the spread of this pandemic infection.

Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at root s(NN)=2.76 TeV

Abstract: We report on the first measurement of the triangular nu(3), quadrangular nu(4), and pentagonal nu(5) charged particle flow in Pb-Pb collisions at root s(NN) = 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow nu(2) and nu(3) have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.

Convertible organic nanoparticles for near-infrared photothermal ablation of cancer cells.

Abstract: Well-designed photothermal nanomaterials have attractedthe interest of many scientists pursuing a better means toaccurately diagnose cancer and assess the efficacy of treat-ment, because these materials enable therapies in which thetumor region is pin-pointed with a laser-guided light sourcewithout surgical intervention.

Ultrasonography and the Ultrasound-Based Management of Thyroid Nodules: Consensus Statement and Recommendations

Abstract: The detection of thyroid nodules has become more common with the widespread use of ultrasonography (US). US is the mainstay for detecting and making the differential diagnosis of thyroid nodules as well as for providing guidance for a biopsy. The Task Force on Thyroid Nodules of the Korean Society of Thyroid Radiology has developed recommendations for the US diagnosis and US-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature, the results of multicenter studies and from the consensus of experts.

Continuous separation of breast cancer cells from blood samples using multi-orifice flow fractionation (MOFF) and dielectrophoresis (DEP)

Abstract: Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer, so their isolations and quantifications are important for biomedical applications such as cancer prognosis and measuring the responses to drug treatments. In this paper, we present the development of a microfluidic device for the separation of CTCs from blood cells based on the physical properties of cells. For use as a CTC model, we successfully separated human breast cancer cells (MCF-7) from a spiked blood cell sample by combining multi-orifice flow fractionation (MOFF) and dielectrophoretic (DEP) cell separation technique. Hydrodynamic separation takes advantage of the massive and high-throughput filtration of blood cells as it can accommodate a very high flow rate. DEP separation plays a role in precise post-processing to enhance the efficiency of the separation. The serial combination of these two different sorting techniques enabled high-speed continuous flow-through separation without labeling. We observed up to a 162-fold increase in MCF-7 cells at a 126 µL min−1 flow rate. Red and white blood cells were efficiently removed with separation efficiencies of 99.24% and 94.23% respectively. Therefore, we suggest that our system could be used for separation and detection of CTCs from blood cells for biomedical applications.

An odyssey into virtual worlds: exploring the impacts of technological and spatial environments on intention to purchase virtual products

Abstract: Although research on three-dimensional virtual environments abounds, little is known about the social and business aspects of virtual worlds. Given the emergence of large-scale social virtual worlds, such as Second Life, and the dramatic growth in sales of virtual goods, it is important to understand the dynamics that govern the purchase of virtual goods in virtual worlds. Employing the stimulus-organism-response (S-O-R) framework, we investigate how technological (interactivity and sociability) and spatial (density and stability) environments in virtual worlds influence the participants' virtual experiences (telepresence, social presence, and flow), and how experiences subsequently affect their response (intention to purchase virtual goods). The results of our survey of 354 Second Life residents indicate that interactivity, which enhances the interaction with objects, has a significant positive impact on telepresence and flow. Also, sociability, which fosters interactions with participants, is significantly associated with social presence, although no such significant impact was observed on flow. Furthermore, both density and stability are found to significantly influence participants' virtual experiences; stability helps users to develop strong social bonds, thereby increasing both social presence and flow. However, contrary to our prediction of curvilinear patterns, density is linearly associated with flow and social presence. Interestingly, the results exhibit two opposing effects of density: while it reduces the extent of flow, density increases the amount of social presence. Since social presence is found to increase flow, the net impact of density on flow depends heavily on the relative strength of the associations involving these three constructs. Finally, we find that flow mediates the impacts of technological and spatial environments on intention to purchase virtual products. We conclude the paper with a discussion of the theoretical and practical contributions of our findings.

A p53/miRNA-34 axis regulates Snail1-dependent cancer cell epithelial–mesenchymal transition

Abstract: Snail1 is a zinc finger transcriptional repressor whose pathological expression has been linked to cancer cell epithelial–mesenchymal transition (EMT) programs and the induction of tissue-invasive activity, but pro-oncogenic events capable of regulating Snail1 activity remain largely uncharacterized. Herein, we demonstrate that p53 loss-of-function or mutation promotes cancer cell EMT by de-repressing Snail1 protein expression and activity. In the absence of wild-type p53 function, Snail1-dependent EMT is activated in colon, breast, and lung carcinoma cells as a consequence of a decrease in miRNA-34 levels, which suppress Snail1 activity by binding to highly conserved 3′ untranslated regions in Snail1 itself as well as those of key Snail1 regulatory molecules, including β-catenin, LEF1, and Axin2. Although p53 activity can impact cell cycle regulation, apoptosis, and DNA repair pathways, the EMT and invasion programs initiated by p53 loss of function or mutation are completely dependent on Snail1 expression. These results identify a new link between p53, miR-34, and Snail1 in the regulation of cancer cell EMT programs.