Showing papers by "Hanyang University published in 2005"

Image-guided Tumor Ablation: Standardization of Terminology and Reporting Criteria

Abstract: The field of interventional oncology with use of image-guided tumor ablation requires standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison between treatments that use different technologies, such as chemical (ethanol or acetic acid) ablation, and thermal therapies, such as radiofrequency, laser, microwave, ultrasound, and cryoablation. This document provides a framework that will hopefully facilitate the clearest communication between investigators and will provide the greatest flexibility in comparison between the many new, exciting, and emerging technologies. An appropriate vehicle for reporting the various aspects of image-guided ablation therapy, including classification of therapies and procedure terms, appropriate descriptors of imaging guidance, and terminology to define imaging and pathologic findings, are outlined. Methods for standardizing the reporting of follow-up findings and complications and other important aspects that require attention when reporting clinical results are addressed. It is the group's intention that adherence to the recommendations will facilitate achievement of the group's main objective: improved precision and communication in this field that lead to more accurate comparison of technologies and results and, ultimately, to improved patient outcomes.

Characteristics of basalt fiber as a strengthening material for concrete structures

Abstract: This study investigates the applicability of the basalt fiber as a strengthening material for structural concrete members through various experimental works for durability, mechanical properties, and flexural strengthening. The basalt fiber used in this study was manufactured in Russia and exhibited the tensile strength of 1000 MPa, which was about 30% of the carbon and 60% of the high strength glass (S-glass) fiber. When the fibers were immersed into an alkali solution, the basalt and glass fibers lost their volumes and strengths with a reaction product on the surface but the carbon fiber did not show significant strength reduction. From the accelerated weathering test, the basalt fiber was found to provide better resistance than the glass fiber. However, the basalt fiber kept about 90% of the normal temperature strength after exposure at 600 °C for 2 h whereas the carbon and the glass fibers did not maintain their volumetric integrity. In the tests for flexural strengthening evaluation, the basalt fiber strengthening improved both the yielding and the ultimate strength of the beam specimen up to 27% depending on the number of layers applied. From the results presented herein, two layers of the basalt fiber sheets were thought to be better strengthening scheme. In addition, the strengthening does not need to extend over the entire length of the flexural member. When moderate structural strengthening but high resistance for fire is simultaneously sought such as for building structures, the basalt fiber strengthening will be a good alternative methodology among other fiber reinforced polymer (FRP) strengthening systems.

Role of Alumina Coating on Li−Ni−Co−Mn−O Particles as Positive Electrode Material for Lithium-Ion Batteries

Abstract: The interface reaction between Al2O3-coated Li[Li0.05Ni0.4Co0.15Mn0.4]O2 and liquid electrolyte was investigated. The Al2O3-coated Li[Li0.05Ni0.4Co0.15Mn0.4]O2 showed no large difference in the bulk structure, comparing to bare Li[Li0.05Ni0.4Co0.15Mn0.4]O2. The coated Al2O3 was found to have an amorphous structure from X-ray diffraction study. A small amount of Al2O3 coating (0.25 wt % in the final composition) showed that a uniform mesoporous Al2O3-coating layer whose thickness is of about 5 nm covers Li[Li0.05Ni0.4Co0.15Mn0.4]O2 particles, as confirmed by transmission electron microscopy. At higher concentration (2.5 wt % in the final composition), the irregular tens of nanometer-sized Al2O3 powders were observed on the surface of the active material instead of the uniform coating layer. Despite the insulating nature of Al2O3, the thin coating was effective to improve the battery performances, depending on the thickness of the Al2O3-coating layer, and used electrolytic salt. The Al2O3 coating resulted i...

Patient-Specific Embryonic Stem Cells Derived from Human SCNT Blastocysts

Abstract: Patient-specific, immune-matched human embryonic stem cells (hESCs) are anticipated to be of great biomedical importance for studies of disease and development and to advance clinical deliberations regarding stem cell transplantation. Eleven hESC lines were established by somatic cell nuclear transfer (SCNT) of skin cells from patients with disease or injury into donated oocytes. These lines, nuclear transfer (NT)-hESCs, grown on human feeders from the same NT donor or from genetically unrelated individuals, were established at high rates, regardless of NT donor sex or age. NT-hESCs were pluripotent, chromosomally normal, and matched the NT patient's DNA. The major histocompatibility complex identity of each NT-hESC when compared to the patient's own showed immunological compatibility, which is important for eventual transplantation. With the generation of these NT-hESCs, evaluations of genetic and epigenetic stability can be made. Additional work remains to be done regarding the development of reliable directed differentiation and the elimination of remaining animal components. Before clinical use of these cells can occur, preclinical evidence is required to prove that transplantation of differentiated NT-hESCs can be safe, effective, and tolerated.

Synthesis and characterization of Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 with the microscale core-shell structure as the positive electrode material for lithium batteries.

Abstract: The high capacity of Ni-rich Li[Ni(1-x)M(x)]O(2) (M = Co, Mn) is very attractive, if the structural instability and thermal properties are improved. Li[Ni(0.5)Mn(0.5)]O(2) has good thermal and structural stabilities, but it has a low capacity and rate capability relative to the Ni-rich Li[Ni(1-x)M(x)]O(2). We synthesized a spherical core-shell structure with a high capacity (from the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) core) and a good thermal stability (from the Li[Ni(0.5)Mn(0.5)]O(2) shell). This report is about the microscale spherical core-shell structure, that is, Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) as the core and a Li[Ni(0.5)Mn(0.5)]O(2) as the shell. A high capacity was delivered from the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) core, and a high thermal stability was achieved by the Li[Ni(0.5)Mn(0.5)]O(2) shell. The core-shell structured Li[(Ni(0.8)Co(0.1)Mn(0.1))(0.8)(Ni(0.5)Mn(0.5))(0.2)]O(2)/carbon cell had a superior cyclability and thermal stability relative to the Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) at the 1 C rate for 500 cycles. The core-shell structured Li[(Ni(0.8)Co(0.1)Mn(0.1))(0.8)(Ni(0.5)Mn(0.5))(0.2)]O(2) as a new positive electrode material is a significant breakthrough in the development of high-capacity lithium batteries.

The harmony search heuristic algorithm for discrete structural optimization

Abstract: Many methods have been developed and are in use for structural size optimization problems, in which the cross-sectional areas or sizing variables are usually assumed to be continuous. In most practical structural engineering design problems, however, the design variables are discrete. This paper proposes an efficient optimization method for structures with discrete-sized variables based on the harmony search (HS) heuristic algorithm. The recently developed HS algorithm was conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. In this article, a discrete search strategy using the HS algorithm is presented in detail and its effectiveness and robustness, as compared to current discrete optimization methods, are demonstrated through several standard truss examples. The numerical results reveal that the proposed method is a powerful search and design optimization tool f...

An International Cohort Study of Cancer in Systemic Lupus Erythematosus

Abstract: Objective There is increasing evidence in support of an association between systemic lupus erythematosus (SLE) and malignancy, but in earlier studies the association could not be quantified precisely The present study was undertaken to ascertain the incidence of cancer in SLE patients, compared with that in the general population Methods We assembled a multisite (23 centers) international cohort of patients diagnosed as having SLE Patients at each center were linked to regional tumor registries to determine cancer occurrence Standardized incidence ratios (SIRs) were calculated as the ratio of observed to expected cancers Cancers expected were determined by multiplying person-years in the cohort by the geographically matched age, sex, and calendar year-specific cancer rates, and summing over all person-years Results The 9,547 patients from 23 centers were observed for a total of 76,948 patient-years, with an average followup of 8 years Within the observation interval, 431 cancers occurred The data confirmed an increased risk of cancer among patients with SLE For all cancers combined, the SIR estimate was 115 (95% confidence interval [95% CI] 105-127), for all hematologic malignancies, it was 275 (95% CI 213-349), and for non-Hodgkin's lymphoma, it was 364 (95% CI 263-493) The data also suggested an increased risk of lung cancer (SIR 137; 95% CI 105-176), and hepatobiliary cancer (SIR 260; 95% CI 125, 478) Conclusion These results support the notion of an association between SLE and cancer and more precisely define the risk of non-Hodgkin's lymphoma in SLE It is not yet known whether this association is mediated by genetic factors or exogenous exposures

A functional variant in FCRL3 , encoding Fc receptor-like 3, is associated with rheumatoid arthritis and several autoimmunities

Abstract: Rheumatoid arthritis is a common autoimmune disease with a complex genetic etiology. Here we identify a SNP in the promoter region of FCRL3, a member of the Fc receptor-like family, that is associated with susceptibility to rheumatoid arthritis (odds ratio = 2.15, P = 0.00000085). This polymorphism alters the binding affinity of nuclear factor-κB and regulates FCRL3 expression. We observed high FCRL3 expression on B cells and augmented autoantibody production in individuals with the disease-susceptible genotype. We also found associations between the SNP and susceptibility to autoimmune thyroid disease and systemic lupus erythematosus. FCRL3 may therefore have a pivotal role in autoimmunity.

The effect of filler particle size on the antibacterial properties of compounded polymer/silver fibers

Abstract: Antibacterial activity has become a significant property of textiles used in applications such as medicine, clothing, and household products. In this study, we compounded polypropylene with either micro- or nano-sized silver powders. These polypropylene/silver compounds were prepared by direct melt-compounding using a conventional twin-screw mixer. We analyzed the characteristics of the compounds using wide-angle X-ray diffractometry (WAXS), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The DSC and WAXS results indicated that the crystallinity of the polypropylene component decreased slightly when compared with that of the pure polymer. The SEM micrographs indicated that the silver particles had good dispersibility in the matrix. We measured the mechanical properties of these materials using a universal tensile tester and evaluated the antibacterial activities of these compounds by performing quantitative antibacterial tests using the AATCC-100 test method. From these evaluations of antibacterial activity, we conclude that the compounds incorporating the silver nanoparticles exhibited superior antibacterial activity relative to the samples containing micron-sized particles.

In vitro and in vivo analyses of human embryonic stem cell‐derived dopamine neurons

Abstract: Human embryonic stem (hES) cells, due to their capacity of multipotency and self-renewal, may serve as a valuable experimental tool for human developmental biology and may provide an unlimited cell source for cell replacement therapy. The purpose of this study was to assess the developmental potential of hES cells to replace the selectively lost midbrain dopamine (DA) neurons in Parkinson's disease. Here, we report the development of an in vitro differentiation protocol to derive an enriched population of midbrain DA neurons from hES cells. Neural induction of hES cells co-cultured with stromal cells, followed by expansion of the resulting neural precursor cells, efficiently generated DA neurons with concomitant expression of transcriptional factors related to midbrain DA development, such as Pax2, En1 (Engrailed-1), Nurr1, and Lmx1b. Using our procedure, the majority of differentiated hES cells (> 95%) contained neuronal or neural precursor markers and a high percentage (> 40%) of TuJ1+ neurons was tyrosine hydroxylase (TH)+, while none of them expressed the undifferentiated ES cell marker, Oct 3/4. Furthermore, hES cell-derived DA neurons demonstrated functionality in vitro, releasing DA in response to KCl-induced depolarization and reuptake of DA. Finally, transplantation of hES-derived DA neurons into the striatum of hemi-parkinsonian rats failed to result in improvement of their behavioral deficits as determined by amphetamine-induced rotation and step-adjustment. Immunohistochemical analyses of grafted brains revealed that abundant hES-derived cells (human nuclei+ cells) survived in the grafts, but none of them were TH+. Therefore, unlike those from mouse ES cells, hES cell-derived DA neurons either do not survive or their DA phenotype is unstable when grafted into rodent brains.

Cross-cultural adaptation and validation of the Korean version of the EQ-5D in patients with rheumatic diseases.

Abstract: Objectives: This study aimed to determine the cross-cultural adaptation and validation of the Korean version of the EQ-5D in rheumatic conditions. Methods: Translation, back-translation and cognitive debriefing were performed according to the EuroQol group’s guidelines. For validity, 508 patients were recruited and administered the EQ-5D, Short-Form 36 and condition-specific measures. Construct validity and sensitivity were evaluated by testing a-priori hypotheses. For reliability, another 57 patients repeated the EQ-5D at 1-week interval, and intra-class correlations (ICC) and kappa statistics were estimated. For responsiveness, another 60 patients repeated it at 12-week interval within the context of clinical trial, and standardized response mean(SRM) were calculated. Results: The cross-cultural adaptation produced no major modifications in the scale. The associations of the EQ-5D with the generic- and condition-specific measures were observed as expected in hypotheses the higher: EQ-5Dindex and EQ-5DVAS scores, the better health status by generic- or condition-specific measures, and the better functional class. The ICCs were 0.751 and 0.767, respectively, and kappa ranged from 0.455 to 0.772. The SRM were 0.649 and 0.410, respectively. Conclusion: The Korean EQ-5D exhibits good validity and sensitivity in various rheumatic conditions. Although its reliability and responsiveness were not excellent, it seems acceptable if condition-specific measures are applied together.

Indole-based macrocycles as a class of receptors for anions

Abstract: The development of synthetic receptors and chemosensors for anions has attracted much attention in recent years as the fundamental role of anions in biological and chemical processes has become increasingly understood. Biomacromolecules such as sulfate-binding proteins and a CIC chloride channel make use of hydrogen bonds as a major driving force to bind or transport anions through cell membranes. Similarly, hydrogen-bonding interactions are widely implemented for the construction of artificial receptors, and amido and ureido groups have frequently been incorporated for this purpose. 4] Furthermore, the pyrrolic NH group has also been used as a hydrogen-bond donor to an anion, as demonstrated in calixpyrroles, expanded porphyrinoids, and amidopyrroles. Herein, we describe the synthesis and binding properties of indole-based macrocycles 1 and 2, which can function as a new class of synthetic receptors for anions. The macrocycles contain a well-defined internal cavity surrounded by four indole NH hydrogen atoms, thus are capable of binding anions strongly through hydrogen-bonding interactions. More interestingly, 1 and 2 showed separate sets of H NMR signals for the free macrocycles and their complexes at room temperature in all cases and thus can serve as chemosensors for anions based on H NMR chemical shifts. The synthesis of 1 and 2 is outlined in Scheme 1. The key molecular building block 7,7’-diiodo-2,2’-biindole (4) was prepared by oxidative dimerization (Cu(OAc)2, 95%) [9]

A small wideband microstrip-fed monopole antenna

Abstract: A small microstrip-fed monopole antenna, which consists of a rectangular patch and a truncated ground plane, is presented for ultra wideband application. The proposed antenna is designed to operate over 3.1 to 11GHz for S/sub 11/<-10dB. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest.

Nanocrystalline TiO2/ZnO thin films: fabrication and application to dye-sensitized solar cells.

Abstract: Nanocrystalline TiO2 thin films composed of densely packed grains were deposited onto indium-doped tin oxide (ITO)-coated glass substrates at room temperature using a chemical bath deposition technique. A layer-by-layer (LbL) process was utilized to obtain a 1.418-μm-thick TiO2/ZnO structure. The TiO2 surface was super-hydrophilic, but its hydrophilicity decreased considerably after ZnO deposition. Other TiO2/ZnO films were studied to assess their suitability as photoelectrodes in dye-sensitized solar cells (DSSCs).

Fasting Whole Blood as a Biomarker of Essential Fatty Acid Intake in Epidemiologic Studies: Comparison with Adipose Tissue and Plasma

Abstract: Biomarkers could provide a more accurate measure of long-term intake than questionnaires. Adipose tissue is considered the best indicator of long-term essential fatty acid intake, but other tissues may prove equally valid. The authors evaluated the ability of fasting whole blood, relative to fasting plasma and adipose tissue, to reflect fatty acid intake. Costa Rican men (n ¼ 99) and women (n ¼ 101) completed a 135-item food frequency questionnaire and provided adipose tissue and blood samples from 1999 to 2001. Fatty acids were identified by using capillary gas chromatography. Correlation coefficients adjusted for age, sex, and body mass index were calculated. Diettissue correlation coefficients for a-linolenic acid and linoleic acid, respectively, were 0.38 and 0.43 in whole blood, 0.51 and 0.52 in adipose tissue, and 0.39 and 0.41 in plasma. High correlations were observed between wholeblood a-linolenic and linoleic acid and adipose tissue (r ¼ 0.59 and r ¼ 0.67) and plasma (r ¼ 0.96 and r ¼ 0.88), respectively. Results show that fasting whole blood is a suitable biomarker of long-term essential fatty acid intake, and its performance is comparable to that of fasting plasma. Thus, fasting whole blood could be the sample of choice in epidemiologic studies because of its ability to predict intake, its accessibility, and minimum sample processing.

Design and fabrication of a locomotive mechanism for capsule-type endoscopes using shape memory alloys (SMAs)

Abstract: Endoscopes are medical devices to diagnose various kinds of diseases throughout the whole gastrointestinal tracks. Generally, they are divided into conventional push-type endoscopes and more recently developed wireless capsule-type endoscopes. The conventional endoscopes cannot reach the small intestines and generate pain and discomfort to patients due to the stiffness of their body. Such disadvantages do not exist in wireless capsule-type endoscopes. However, commercialized capsule-type endoscopes move passively by peristaltic waves (and the gravity), which makes it impossible for doctors to diagnose the areas of his or her interest more thoroughly and actively. To address this problem of passivity, a locomotive mechanism is proposed for wireless capsule-type endoscopes. Prototypes with micro brushless dc motors, ionic polymer metal composite actuator, and shape memory alloy (SMA) wires are designed and fabricated for preliminary tests. Based on the tests, spring-type SMA actuators are selected to be microactuators for capsule endoscopes. Thus, two-way linear actuators using a pair of SMA springs are developed based on a static analysis on them. Moreover, a simple and effective clamping device is developed based on biomimetic approach. A prototype endoscope with four pairs of SMA springs and four clampers was developed. It has 13 mm in diameter and 33 mm in total length, with a hollow space of 7.6 mm in diameter to house other parts that are needed for endoscopy such as a camera, an RF module, sensors, e.g., for endoscopic ultrasound, and a battery. A sequential control of the four actuators improves the efficiency of locomotion up to four times. To validate the performance of the proposed locomotive mechanism, a series of experiments were carried out including in-vitro tests. The results of the experiments indicate that the proposed locomotion mechanism is effective to be used for micro capsule-type endoscopes.

Posterior tibial tendon insufficiency: which ligaments are involved?

Abstract: Background: The pathology manifested in posterior tibial tendon insufficiency (PTTI) is not limited to the posterior tibial tendon. The association of ligament failure with deformity has been discussed in numerous publications, but extensive documentation of the structures involved has not been performed. The purpose of this observational study was to identify the pattern of ligament involvement using standarized, high-resolution magnetic resonance imaging (MRI) in a series of 31 consecutive patients diagnosed with PTTI compared to an age matched control group without PTTI. Method: The structures evaluated by MRI were the posterior tibial tendon, superomedial and inferomedial components of the spring ligament complex, talocalcaneal interosseous ligament, long and short plantar ligaments, plantar fascia, deltoid ligament, plantar naviculocuneiform ligament, and tarsometatarsal ligaments. Structural derangement was graded on a five-part scale (0 to IV) with level 0 being normal and level IV indicating a tea...

Small-diameter blood vessels engineered with bone marrow-derived cells.

Abstract: Therapies for coronary artery disease and peripheral vascular disease often require replacement of the diseased vessels with vascular grafts. Autologous arteries or veins are the best substitutes for small-diameter (internal diameter [ID] < 6 mm) vessels.1 However, many patients do not have vessels suitable for grafting due to preexisting vascular diseases or vessel use in previous procedures. Therefore, there have been attempts to develop a small-diameter vascular graft made of synthetic or natural polymers. The synthetic polymeric materials include polyethylene terephthalate and expanded polytetrafluoroethylene (ePTFE).2 Although these polymeric vascular grafts have been successfully employed to replace blood vessels above 6 mm in ID, these polymeric grafts cannot be used for treatment of small-diameter vascular diseases due to thrombus formation.3,4 Coating of the intimal side with antithrombogenic materials, such as heparin,5 polyethylene oxide,6 or endothelial cells (ECs),7 has been applied to solve this problem, but these approaches were unsuccessful. A decellularized tissue matrix has been shown to be successfully remodeled into cellularized vessels after implantation in rabbits.8 However, this result may not be relevant to humans, because endothelial-cell development on vascular grafts in humans is much slower than in rabbits.9 Recently, tissue-engineering techniques have been applied to develop small-diameter vascular grafts. Several studies have fabricated small-diameter vascular grafts by culturing smooth muscle cells (SMCs) and ECs,10–12 which were isolated from autologous blood vessels, either on biodegradable polymer scaffolds or without exogenous materials, but these grafts developed thrombosis shortly after implantation.11,12 Another drawback of this approach is that the graft fabrication procedures involve a blood vessel biopsy to obtain vascular cell sources, which may result in potential morbidity at the donor sites and could be limited by a healthy autologous vessel shortage. Another cell source for tissue engineering of vascular grafts is multipotent stem cell. Recently, vascular grafts fabricated by seeding endothelial progenitor cells (EPCs) derived from peripheral blood onto decellularized vessels were shown to maintain patency for 130 days in the ovine model.13 However, seeding only with EPCs would not induce complete smooth muscle (SM) regeneration in the arterial grafts. Bone marrow–derived cells (BMCs) could be an alternative stem cell source for vascular tissue engineering. BMCs have demonstrated the ability to differentiate into multiple mesenchymal cell lineages.14,15 Recently, BMCs have been shown to differentiate into endothelial-like cells16–19 and vascular SM-like cells.20–23 Furthermore, several studies have demonstrated that bone marrow mononuclear cells (BMMNCs) contribute to histogenesis of tissue-engineered large-diameter vascular grafts24 and that bone marrow CD34-positive cells enhance the graft endothelialization in vivo.25 In this study, we attempted to develop small-diameter (ID = 3 mm) vascular grafts using BMCs and showed that BMC seeding significantly improved the patency of tissue-engineered small-diameter vascular grafts. Small-diameter blood vessels were fabricated by seeding 2 types of vascular cells differentiated from autologous BMMNCs onto decellularized carotid arteries and implanted in canine models. Prior to cell seeding, BMCs were induced to differentiate in vitro into SM α-actin/SM myosin heavy-chain (SMMHC)–positive cells and von Willebrand factor (vWF)/CD31-positive cells by culturing BMCs in different types of media. Decellularized arteries were used as scaffolds for vascular tissue reconstruction because these scaffolds preserved biochemical components and structures of native extracellular matrices (ECMs) of blood vessels. The vascular tissue regeneration and graft patency were examined.

Three-dimensional imaging methods based on multiview images

Abstract: Three-dimensional imaging methods, based on parallaxes as their depth cues, can be classified into the stereoscopic providing binocular parallax only, and multiview providing both binocular and motion parallaxes. In these methods, the parallaxes are provided by creating a viewing zone with use of either a special optical eyeglasses or a special optical plate as their viewing zone-forming optics. For the stereoscopic image generations, either the eyeglasses or the optical plate can be employed, but for the multiview the optical plate or the eyeglasses with a tracking device. The stereoscopic image pair and the multiview images are presented either simultaneously or as a time sequence with use of projectors or display panels. For the case of multiview images, they can also be presented as two images at a time according to the viewer's movements. The presence of the viewing zone-forming optics often causes undesirable problems, such as appearance of moire/spl acute/ fringes, image quality deterioration, depth reversion, limiting viewing regions, low image brightness, image blurring, and inconveniences of wearing.