434 results on '"C.-W. Lee"'
Search Results
52. Plk1-mediated stabilization of 53BP1 through USP7 regulates centrosome positioning to maintain bipolarity
- Author
-
S-B Shin, Hyungshin Yim, Raymond L. Erikson, S U Woo, and P C-W Lee
- Subjects
0301 basic medicine ,Cancer Research ,DNA damage ,Mitosis ,Cell Cycle Proteins ,Spindle Apparatus ,Protein Serine-Threonine Kinases ,PLK1 ,Spindle pole body ,Ubiquitin-Specific Peptidase 7 ,03 medical and health sciences ,Proto-Oncogene Proteins ,Genetics ,Humans ,Phosphorylation ,Molecular Biology ,Centromere Protein F ,Centrosome ,biology ,CENPF ,Cell Polarity ,Cell cycle ,Cell biology ,030104 developmental biology ,biology.protein ,Tumor Suppressor p53-Binding Protein 1 ,Ubiquitin Thiolesterase ,HeLa Cells - Abstract
Although 53BP1 has been established well as a mediator in DNA damage response, its function in mitosis is not clearly understood. We found that 53BP1 is a mitotic-binding partner of the kinases Plk1 and AuroraA, and that the binding with Plk1 increases the stability of 53BP1 by accelerating its interaction with the deubiquitinase USP7. Depletion of 53BP1 induces mitotic defects such as chromosomal missegregation, misorientation of spindle poles and the generation of extra centrosomes, which is similar phenotype to USP7-knockdown cells. In addition, 53BP1 depletion reduces the levels of p53 and centromere protein F (CENPF), interacting proteins of 53BP1. These phenotypes induced by 53BP1 depletion were rescued by expression of wild-type or phosphomimic mutant 53BP1 but not by expression of a dephosphomimic mutant. We propose that phosphorylation of 53BP1 at S380 accelerates complex formation with USP7 and CENPF to regulate their stability, thus having a crucial role in proper centrosome positioning, chromosomal alignment, and centrosome number.
- Published
- 2016
53. Abstract P5-07-13: Identification of a cancer stem sell-specific function for the histone deacetylases, HDAC1 and HDAC7, in breast and ovarian cancer
- Author
-
Richard A. Young, Claes Wahlestedt, Tan A. Ince, A. B. Gropper, J. Grosso, Diana J. Azzam, Ti Lee, Fabio Petrocca, Corrado Caslini, Andrea L. Richardson, Bin Wang, Ramin Shiekhattar, C-W Lee, Abigail E. Witt, EA Cohick, and Michelle Jones
- Subjects
Oncology ,Cancer Research ,medicine.medical_specialty ,biology ,business.industry ,Specific function ,HDAC7 ,Cancer ,medicine.disease ,HDAC1 ,Histone ,Internal medicine ,biology.protein ,Cancer research ,Medicine ,Identification (biology) ,business ,Ovarian cancer - Abstract
This abstract was withdrawn by the authors.
- Published
- 2017
54. Estimates for Brascamp-Lieb forms in $L^p$ spaces with power weights
- Author
-
Russell M. Brown, C. W. Lee, and Katharine A. Ott
- Subjects
Pure mathematics ,Mathematics::Functional Analysis ,26B15 ,Mathematics - Classical Analysis and ODEs ,Applied Mathematics ,General Mathematics ,Classical Analysis and ODEs (math.CA) ,FOS: Mathematics ,Mathematics ,Power (physics) - Abstract
We establish a set of necessary conditions and a set of sufficient conditions for boundedness of a family of Brascamp-Lieb forms in Lorentz spaces and $L^p$-spaces with power weights. The conditions are close to optimal., 15 pages, updated version with minor changes suggested by referee. New material discussing multi-linear fractional integrals
- Published
- 2018
55. Targeting Semaphorin 3C in Prostate Cancer With Small Molecules
- Author
-
Kevin J. Tam, Yifan Gong, Benjamin Vanderkruk, Christopher J. Ong, Ivy Z. F. Jiao, Liangliang Liu, James W. Peacock, Luke Gooding, Kevin C.K. Lee, Artem Cherkasov, Chung C W Lee, Colin G Sedgwick, Ashley Shepherd, Kush Dalal, Tabitha Tombe, Satyam Bhasin, Ravi Shashi Nayana Munuganti, and Martin E. Gleave
- Subjects
0301 basic medicine ,Endocrinology, Diabetes and Metabolism ,medicine.medical_treatment ,small molecule ,plexin ,Receptor tyrosine kinase ,03 medical and health sciences ,Prostate cancer ,Semaphorin ,Neuropilin 1 ,medicine ,Neuropilin ,Hormones and Cancer ,Research Articles ,biology ,business.industry ,semaphorin 3C ,Cancer ,medicine.disease ,prostate cancer ,3. Good health ,Androgen receptor ,Radiation therapy ,030104 developmental biology ,biology.protein ,Cancer research ,neuropilin ,business - Abstract
Despite the amenability of early-stage prostate cancer to surgery and radiation therapy, locally advanced and metastatic prostate cancer is clinically problematic. Chemical castration is often used as a first-line therapy for advanced disease, but progression to the castration-resistant prostate cancer phase occurs with dependable frequency, largely through mutations to the androgen receptor (AR), aberrant AR signaling, and AR-independent mechanisms, among other causes. Semaphorin 3C (SEMA3C) is a secreted signaling protein that is essential for cardiac and neuronal development and has been shown to be regulated by the AR, to drive epithelial-to-mesenchymal transition and stem features in prostate cells, to activate receptor tyrosine kinases, and to promote cancer progression. Given that SEMA3C is linked to several key aspects of prostate cancer progression, we set out to explore SEMA3C inhibition by small molecules as a prospective cancer therapy. A homology-based SEMA3C protein structure was created, and its interaction with the neuropilin (NRP)-1 receptor was modeled to guide the development of the corresponding disrupting compounds. Experimental screening of 146 in silico‒identified molecules from the National Cancer Institute library led to the discovery of four promising candidates that effectively bind to SEMA3C, inhibit its association with NRP1, and attenuate prostate cancer growth. These findings provide proof of concept for the feasibility of inhibiting SEMA3C with small molecules as a therapeutic approach for prostate cancer.
- Published
- 2018
56. Three-in-one protocol reduces mortality of patients with haemodynamically unstable pelvic fractures-a five year multi-centred review in Hong Kong
- Author
-
Ning Tang, Shing-Hing Choi, Annice-M L Chang, John-K S Wong, Alexander-C W Lee, Gilberto-K K Leung, Janice-H H Yeung, Chak-Wah Kam, HT Wong, H. F. Ho, Kin-Yan Lee, Philip-C H Kwok, Tak-Wing Lau, Ming Leung, Mina Cheng, Kevin-Y K Wong, Lily-P S Chan, Kin-Bong Lee, and Nai-Kwong Cheung
- Subjects
Damage control ,Adult ,Male ,medicine.medical_specialty ,030230 surgery ,Cohort Studies ,03 medical and health sciences ,Fractures, Bone ,Young Adult ,0302 clinical medicine ,Trauma Centers ,Fracture Fixation ,medicine ,Humans ,Orthopedics and Sports Medicine ,Hospital Mortality ,Pelvic Bones ,Retrospective Studies ,Protocol (science) ,business.industry ,Hemostatic Techniques ,Mortality rate ,Angiography ,Hemodynamics ,030208 emergency & critical care medicine ,Middle Aged ,medicine.disease ,Predictive factor ,Survival Rate ,Treatment Outcome ,Mechanism of injury ,Emergency medicine ,Orthopedic surgery ,Pelvic fracture ,Hong Kong ,Surgery ,Female ,business ,Cohort study - Abstract
The mortality rate in patients with haemodynamically unstable pelvic fractures is as high as 40–60%. Despite the new advances in trauma care which are in phase in trauma centres in Hong Kong, the management of haemodynamically unstable pelvic fracture is still heterogeneous. The aim of this study is to review the results of management of haemodynamically unstable pelvic fracture patients in Hong Kong over a five year period. This is a retrospective multi-centred cohort study of patients with haemodynamic and mechanically unstable pelvic fractures from 1 January 2010 to 31 December 2014. The primary outcome investigated is mortality of patients (including overall, 30-day, 7-day and 24-hour mortalities). Implementation of three-in-one pelvic damage control protocol was identified to be a significant independent predictive factor for overall, 30-day, seven-day and 24-hour mortalities. The overall in-hospital and 30-day mortality rates for patients managed with three-in-one protocol was 12.5%, while it was 11% for seven day mortality and 6% for 24 hour mortality. There were no significant differences in demographic characteristics, physiological measurements, types of pelvic fracture, severity and mechanism of injury between patients managed with or without three-in-one protocol. Implementation of the multidisciplinary three-in-one pelvic damage control protocol reduces mortality and therefore should be highly recommended. The results are convincing as it has eliminated the limitations of our previous single-centred trial.
- Published
- 2017
57. Investigations in Hydrostatic Planar Bearings Compensated by Tapered-Spool Restrictors II: Load Capacity and Static Stiffness
- Author
-
C.-W. Lee, H.-C. Cheng, S.-Y. Hu, and Y. Kang
- Subjects
Load capacity ,Bearing (mechanical) ,Materials science ,business.industry ,Applied Mathematics ,Mechanical Engineering ,Flow (psychology) ,Antenna aperture ,Stiffness ,02 engineering and technology ,Structural engineering ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,law.invention ,020303 mechanical engineering & transports ,Planar ,0203 mechanical engineering ,law ,medicine ,medicine.symptom ,Hydrostatic equilibrium ,0210 nano-technology ,business ,Displacement (fluid) - Abstract
This study including two parts investigates the influence of design parameters of tapered-spool restrictors and hydrostatic planar bearing on static characteristics of load capacity and static stiffness. The former part provides guides for the design of single-action and double-action tapered-spool restrictors. This part provides design guides for planar hydrostatic bearing and for matching up with tapered-spool restrictor. The equations of flow continuity are utilized to determine the film thickness for open-type planar bearing and worktable displacement for closed-type planar bearing with respect to the recess pressure, respectively. The load capacity can be obtained by multiplying recess pressure by effective area of bearing pad. Furthermore, the static stiffness can be obtained by differentiating the recess pressure with respect to film thickness or worktable displacement. The finding results give that the usage range of recess pressure, and the availability ranges of design parameters of restrictor and bearing parameters. Which are found for getting the maximum stiffness.
- Published
- 2015
58. Investigations in Hydrostatic Planar Bearings Compensated by Tapered-Spool Restrictors I: Flow Rate
- Author
-
H.-C. Cheng, S.-Y. Hu, C.-W. Lee, and Y. Kang
- Subjects
Materials science ,Applied Mathematics ,Mechanical Engineering ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Volumetric flow rate ,law.invention ,020303 mechanical engineering & transports ,Planar ,0203 mechanical engineering ,law ,Hydrostatic equilibrium ,0210 nano-technology - Abstract
This paper is former part of serial studies to investigate the influence of design parameters of tapered-spool type restrictors on static characteristics of hydrostatic bearing. The flow rates passing restrictors can determine the static characteristics of hydrostatic bearings. In this part an analytical method which includes formulas and solving is utilized to simulate dimensionless flow rate in both single-action and double-action tapered-spool restrictors. The numerical results illustrate the variations of flow rates with respect to the change of pressure and pressure difference, respectively. The findings give that the design parameters of tapered-spool restrictors and the useful range of recess pressure. The following part will depend on this paper results to study load capacity and static stiffness of hydrostatic bearing compensated by tapered-spool restrictor.
- Published
- 2015
59. Clinical judgement perplexed by initially undisclosed use of herbal medicine and unexpected cross-reactivity of immunoassay
- Author
-
K T, Liu and C W, Lee
- Subjects
Immunoassay ,Male ,Digoxin ,Bradycardia ,Humans ,Panax ,False Positive Reactions ,Cross Reactions ,Middle Aged - Abstract
We report a case of symptomatic bradycardia caused by consumption of a Chinese herbal medicine which was initially undisclosed to the attending emergency physician. The scientific name of the herb is Panax japonicus. Electrocardiogram revealed sinus bradycardia. Laboratory tests were normal except for the detection of a high serum digoxin level. Further interrogation of the patient eventually disclosed ingestion of the herb which, however, did not contain any digoxin. Other active ingredients in the herb include various types of ginsenoside. These are digoxin-like substances that had caused the observed false-positive detection of digoxin by fluorescence polarization immunoassay due to cross-reactivity. Our case-report provides an important insight about a blind-spot in the field of laboratory medicine (clinical pathology), namely, the false positive detection of digoxin due to crossreactivity in the immunoassay when we come across digoxin-like substances in clinical scenarios, which has barely received attention in the medical literature. It also conveys a clear educational message that with full understanding of the laboratory methodology and its mechanistic rationale there are actually some tricks-of-the-trade that allow us to optimize the specificity of the biochemical tests and the treatment of digoxin-like substances overdose.
- Published
- 2017
60. Development of habitat mapping technology using spatial information
- Author
-
K.-Y. Oh, C.-W. Lee, and M.-J. Lee
- Subjects
Geography ,biology ,Habitat ,biology.animal ,Spatial database ,Prionailurus bengalensis ,Elevation ,Leopard ,Land cover ,biology.organism_classification ,Spatial analysis ,Cartography ,Apex predator - Abstract
The purpose of this study was to create leopard cat (Prionailurus bengalensis) habitat potential maps of South Korea using spatial information. To create maps, we gathered various environmental factors potentially affecting the species’ distribution from a spatial database: elevation, slope, land cover and so on. We analyzed the spatial relationships between the distribution of the leopard cats and the environmental factors using a frequency ratio model. Among the total number of known leopard cat locations, we used 50% for mapping and the remaining 50% for model validation. Our models were relatively successful and showed a high level of accuracy during model validation with existing locations (frequency ratio model 82.15%). These maps can be used to manage and monitor the habitat of mammal species and top predators.
- Published
- 2016
61. Development of a fatigue crack growth testing apparatus and its application to thin titanium foil
- Author
-
C.-W. Lee, J. W. Holmes, and L. Liu
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,chemistry.chemical_element ,Structural engineering ,Paris' law ,Finite element method ,Crack closure ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,General Materials Science ,Growth rate ,Composite material ,business ,Stress intensity factor ,Titanium ,Stress concentration - Abstract
A low-cost experimental apparatus has been developed to investigate the mode I fatigue crack growth behaviour of thin metallic foils and sheets. The apparatus utilizes magnetic coupling between a ceramic magnet and a rotating steel disc to induce cyclic tensile loads in notched rectangular specimens. To illustrate the testing apparatus, mode I fatigue crack growth in 30-µm-thick high-purity titanium foils was studied. Experiments were performed at ambient temperature using a loading frequency of 2 Hz and a nominal stress ratio of 0.1. The cyclic crack growth data could be fit to a Paris relationship between crack growth rate and stress intensity range. The stress intensity factor exponent, m, in the Paris relationship was between 4 and 6, which is comparable with the relatively high values found in the literature for the tension–tension fatigue of other metallic bulk materials. Incomplete self-similarity analysis was used to explain the observed higher m values for thin metallic foils.
- Published
- 2013
62. A Role for Protein Phosphatase 2A in Regulating p38 Mitogen Activated Protein Kinase Activation and Tumor Necrosis Factor-Alpha Expression during Influenza Virus Infection
- Author
-
Allan S. Y. Lau, Alex H. M. Tam, Davy C. W. Lee, and Anna H. Y. Law
- Subjects
MAPK/ERK pathway ,p38 mitogen activated protein kinase ,viruses ,medicine.medical_treatment ,Biology ,medicine.disease_cause ,p38 Mitogen-Activated Protein Kinases ,Article ,influenza virus ,Catalysis ,Virus ,Microbiology ,Proinflammatory cytokine ,lcsh:Chemistry ,Inorganic Chemistry ,Influenza A Virus, H1N1 Subtype ,Catalytic Domain ,Influenza, Human ,Influenza A Virus, H9N2 Subtype ,medicine ,Influenza A virus ,Humans ,Protein Phosphatase 2 ,Phosphorylation ,Physical and Theoretical Chemistry ,lcsh:QH301-705.5 ,Molecular Biology ,Cells, Cultured ,tumor necrosis factor-alpha ,Spectroscopy ,Macrophages ,protein phosphatase 2A ,Organic Chemistry ,virus diseases ,Dual Specificity Phosphatase 1 ,General Medicine ,Protein phosphatase 2 ,Computer Science Applications ,Enzyme Activation ,Cytokine ,lcsh:Biology (General) ,lcsh:QD1-999 ,Immunology ,Tumor necrosis factor alpha ,Signal transduction - Abstract
Influenza viruses of avian origin continue to pose pandemic threats to human health. Some of the H5N1 and H9N2 virus subtypes induce markedly elevated cytokine levels when compared with the seasonal H1N1 virus. We previously showed that H5N1/97 hyperinduces tumor necrosis factor (TNF)-alpha through p38 mitogen activated protein kinase (MAPK). However, the detailed mechanisms of p38MAPK activation and TNF-alpha hyperinduction following influenza virus infections are not known. Negative feedback regulations of cytokine expression play important roles in avoiding overwhelming production of proinflammatory cytokines. Here we hypothesize that protein phosphatases are involved in the regulation of cytokine expressions during influenza virus infection. We investigated the roles of protein phosphatases including MAPK phosphatase-1 (MKP-1) and protein phosphatase type 2A (PP2A) in modulating p38MAPK activation and downstream TNF-alpha expressions in primary human monocyte-derived macrophages (PBMac) infected with H9N2/G1 or H1N1 influenza virus. We demonstrate that H9N2/G1 virus activated p38MAPK and hyperinduced TNF-alpha production in PBMac when compared with H1N1 virus. H9N2/G1 induced PP2A activity in PBMac and, with the treatment of a PP2A inhibitor, p38MAPK phosphorylation and TNF-alpha production were further increased in the virus-infected macrophages. However, H9N2/G1 did not induce the expression of PP2A indicating that the activation of PP2A is not mediated by p38MAPK in virus-infected PBMac. On the other hand, PP2A may not be the targets of H9N2/G1 in the upstream of p38MAPK signaling pathways since H1N1 also induced PP2A activation in primary macrophages. Our results may provide new insights into the control of cytokine dysregulation.
- Published
- 2013
63. Suppression of PU.1-linked TLR4 expression by cilostazol with decrease of cytokine production in macrophages from patients with rheumatoid arthritis
- Author
-
W S Lee, S Y Park, C D Kim, B Y Rhim, K W Hong, S W Lee, S H Baek, and C W Lee
- Subjects
Pharmacology ,business.industry ,medicine.medical_treatment ,Arthritis ,Inflammation ,medicine.disease ,Cilostazol ,IκBα ,Cytokine ,Immunology ,medicine ,TLR4 ,Synovial fluid ,Tumor necrosis factor alpha ,medicine.symptom ,business ,medicine.drug - Abstract
Background and Purpose The present study assessed the effects of cilostazol on LPS-stimulated TLR4 signal pathways in synovial macrophages from patients with rheumatoid arthritis (RA). These effects were confirmed in collagen-induced arthritis (CIA) in mice. Experimental Approach Expression of TLR4, PU.1, NF-κB p65 and IκBα on synovial fluid macrophages from RA patients was determined by Western blotting, and cytokines were measured by elisa. Anti-arthritic effects were evaluated in CIA mice. Key Results Intracellular cAMP was concentration-dependently raised by cilostazol (1–100 μM). Cilostazol significantly suppressed LPS-stimulated increase of TLR4 expression by blocking PU.1 transcriptional activity in RA macrophages. In addition, cilostazol decreased LPS-induced myeloid differentiation factor 88 (MyD88) expression, but not that of TNF receptor-associated factor 6 (TRAF6). Cilostazol also suppressed IkBα degradation and NF-κB p65 nuclear translocation. Moreover, LPS-induced increase of cytokine production (TNF-α, IL-1β) was inhibited by cilostazol, an effect which was accompanied by suppression of IκBα degradation, and NF-κB p65 nuclear translocation. However, expression of anti-inflammatory IL-10 was elevated by cilostazol and forskolin/IBMX. In mice with CIA, post-treatment with cilostazol (30 mg kg−1 day−1) decreased expression of TLR4 in knee joints in association with decreased recruitment of macrophages. Consequently, synovial inflammation, proteoglycan depletion and bone erosion were significantly inhibited by cilostazol treatment. Conclusions and Implications Cilostazol down-regulated LPS-stimulated PU.1-linked TLR4 expression and TLR4/MyD88/NF-κB signal pathways, and then suppressed inflammatory cytokine production in synovial macrophages from RA patients. Also cilostazol markedly inhibited the severity of CIA in mice.
- Published
- 2013
64. Analysis of the association between air pollution and allergic diseases exposure from nearby sources of ambient air pollution within elementary school zones in four Korean cities
- Author
-
Chung-Soo Lee, Ho-Hyun Kim, Young-Wook Lim, Soonju Yu, Jong Hyeok Park, C.-W. Lee, Dong-Chun Shin, and J.-M. Jeon
- Subjects
Male ,Allergy ,Rhinitis, Allergic, Perennial ,Cross-sectional study ,Health, Toxicology and Mutagenesis ,education ,Air pollution ,medicine.disease_cause ,Air Pollution ,Surveys and Questionnaires ,Environmental health ,Statistical significance ,Republic of Korea ,Prevalence ,Humans ,Environmental Chemistry ,Medicine ,Cities ,Child ,Asthma ,Air Pollutants ,Schools ,business.industry ,Environmental engineering ,Questionnaire ,General Medicine ,Atopic dermatitis ,Odds ratio ,Allergens ,medicine.disease ,Rhinitis, Allergic ,Pollution ,Cross-Sectional Studies ,Regression Analysis ,Female ,business ,Environmental Monitoring - Abstract
The objectives of this study were to survey elementary school students regarding the environmental conditions of their elementary schools and to assess the relationship between air pollution and allergic disease using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Therefore, this study was designed as a cross-sectional study. In this study, seven elementary schools were selected and they were classified into three categories. The selection included one school with no traffic-related or other pollutants, three with traffic-related pollutants, and three with traffic-related and other pollutants from industrial and filling station sources. The ISAAC questionnaire survey was given to all of the students except to those in the 1st grade who were presumed to be less likely to be exposed to the school environment than the remainder of the students attending those seven schools. The assessment of allergic disease was conducted on a total of 4,545 students. Three school zones with critical exposure were selected within each school and they were evaluated based on the levels of black carbon (BC), PM10, SO2, NO2, and O3. There was a significant increase in the risks based on the odds ratios of treatment experiences (within 1 year) for allergy-related diseases such as asthma and allergic rhinitis (a) in the school group with traffic-related pollutants and the school group with complex pollutants were 2.12 (1.41-3.19) and 1.59 (1.06-2.37), respectively, in comparison to the school groups with no exposure to pollutants. This was determined based on the odds ratio of symptoms and treatment experiences for allergy-related diseases by group based on the home town zone as a reference. Also, in the case of atopic dermatitis, the odds ratio of treatment experiences (within 1 year) was 1.42 (1.02-1.97), which indicated elevated risks compared to the students in the S1 school. A regression analysis was used to assess the relationship between the substances and the symptomatic experiences within the last year. There were significant increases in the odds ratio of the symptoms associated with allergic rhinitis and the BC and SO2 in the complex pollution areas. The results of the assessment of the relationship between atopic dermatitis-associated symptoms and O3 showed that the odds ratio increased with statistical significance.
- Published
- 2013
65. An Interference Analysis of Interconnection Networks.
- Author
-
Laxmi N. Bhuyan and C. W. Lee
- Published
- 1983
66. Learning in fully recurrent neural networks by approaching tangent planes to constraint surfaces
- Author
-
E. Zhou, P. May, and C. W. Lee
- Subjects
Mathematical optimization ,Cognitive Neuroscience ,Tangent ,Hénon map ,Maxima and minima ,Constraint (information theory) ,Set (abstract data type) ,Recurrent neural network ,Artificial Intelligence ,Simple (abstract algebra) ,Convergence (routing) ,Learning ,Neural Networks, Computer ,Algorithm ,Mathematics - Abstract
In this paper we present a new variant of the online real time recurrent learning algorithm proposed by Williams and Zipser (1989). Whilst the original algorithm utilises gradient information to guide the search towards the minimum training error, it is very slow in most applications and often gets stuck in local minima of the search space. It is also sensitive to the choice of learning rate and requires careful tuning. The new variant adjusts weights by moving to the tangent planes to constraint surfaces. It is simple to implement and requires no parameters to be set manually. Experimental results show that this new algorithm gives significantly faster convergence whilst avoiding problems like local minima.
- Published
- 2012
67. Identification of a cancer stem cell-specific function for the histone deacetylases, HDAC1 and HDAC7, in breast and ovarian cancer
- Author
-
Michelle Jones, Claes Wahlestedt, Evan Cohick, Abigail E. Witt, Andrea L. Richardson, Diana J. Azzam, A. B. Gropper, Fabio Petrocca, J. Grosso, Richard A. Young, Ramin Shiekhattar, Tong Ihn Lee, C. W. Lee, Corrado Caslini, Bin Wang, Tan A. Ince, and Whitehead Institute for Biomedical Research
- Subjects
0301 basic medicine ,Cancer Research ,Breast Neoplasms ,Histone Deacetylase 1 ,Molecular oncology ,Histone Deacetylases ,Metastasis ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Cancer stem cell ,Cell Line, Tumor ,Drug Discovery ,Genetics ,medicine ,Animals ,Humans ,RNA, Small Interfering ,Molecular Biology ,Ovarian Neoplasms ,biology ,Cancer ,Cell cycle ,medicine.disease ,Phenotype ,3. Good health ,Histone Deacetylase Inhibitors ,Disease Models, Animal ,030104 developmental biology ,Histone ,030220 oncology & carcinogenesis ,Gene Knockdown Techniques ,biology.protein ,Cancer research ,Neoplastic Stem Cells ,Heterografts ,Female ,Genes, Lethal ,Original Article ,Ovarian cancer ,Biomarkers - Abstract
Tumours are comprised of a highly heterogeneous population of cells, of which only a small subset of stem-like cells possess the ability to regenerate tumours in vivo. These cancer stem cells (CSCs) represent a significant clinical challenge as they are resistant to conventional cancer therapies and play essential roles in metastasis and tumour relapse. Despite this realization and great interest in CSCs, it has been difficult to develop CSC-targeted treatments due to our limited understanding of CSC biology. Here, we present evidence that specific histone deacetylases (HDACs) play essential roles in the CSC phenotype. Utilizing a novel CSC model, we discovered that the HDACs, HDAC1 and HDAC7, are specifically over-expressed in CSCs when compared to non-stem-tumour-cells (nsTCs). Furthermore, we determine that HDAC1 and HDAC7 are necessary to maintain CSCs, and that over-expression of HDAC7 is sufficient to augment the CSC phenotype. We also demonstrate that clinically available HDAC inhibitors (HDACi) targeting HDAC1 and HDAC7 can be used to preferentially target CSCs. These results provide actionable insights that can be rapidly translated into CSC-specific therapies.
- Published
- 2016
68. Characterization of Toxicity Symptoms of Molybden and Determination of Tissue Threshold Levels for Diagnostic Criteria in Korean Bred Strawberries
- Author
-
Choi JongMyung, Chun JongPil, C. W. Lee, and Nam MinHo
- Subjects
Chemistry ,Phosphorus ,chemistry.chemical_element ,General Medicine ,engineering.material ,chemistry.chemical_compound ,Horticulture ,Nutrient ,Agronomy ,Dry weight ,Chlorophyll ,Toxicity ,engineering ,Phytotoxicity ,Fertilizer ,Plant nutrition - Abstract
This study was carried out to investigate the influence of molybden (Mo) concentrations in fertilizer solution on the growth of and nutrient uptake by domestically bred strawberries. Tissue analysis based on the dry weight was also conducted to determine the threshold levels in plants when Mo toxicity developed in strawberries. The leaf chlorophyll contents decreased lineally as Mo concentrations in the fertilizer solution were elevated. The differences among treatments in chlorophyll contents were statistically significant. The fresh and dry weights decreased significantly when the Mo concentrations in fertilizer solution were higher than 3.0 mM in 'Keumhyang' and 'Maehyang' strawberries and 1.0 mM in 'Seolhyang' strawberry. The elevation of Mo concentrations in fertilizer solution resulted in severe toxicity and crops developed the unique symptoms. The margin of older leaves became yellow and desiccated. Then, the margin of leaf blade rapidly became bronze colored and died as the symptoms spread up the plants. The interveinal area of the young leaves became yellowing. The elevation of Mo concentrations in fertilizer solution did not influence the tissue P, K, and Mg contents based on the dry weight. The tissue Ca contents were higher in 1.0 mM treatment than other treatments of 'Keumhyang' and 'Seolhyang' strawberries. The tissue Mo contents based on the dry weight of 'Keumhyang', 'Maehyang', and 'Seolyahng' strawberries were 76.5, 104.0, and 187.3 , respectively, in the 0.25 mM treatments and 4,155, 5,367, and 2,190 , respectively, in the 4.0 mM treatments. The contents increased lineally as Mo concentrations in fertilizer solution were elevated. When the concentration of Mo at which growth of crops were retarded by 10% is regarded as threshold level, the Mo contents based on dry weight of above ground plant tissue should be lower than 653.4, 686.2, and 589.7 , in 'Keumhyang', 'Maehyang', and 'Seolyahng' strawberries, respectively.
- Published
- 2012
69. Intrarectal administration of mCRAMP-encoding plasmid reverses exacerbated colitis in Cnlp−/− mice
- Author
-
C H Cho, X J Wang, C W Lee, William K.K. Wu, Jun Yu, E K K Tai, Richard L. Gallo, L Yu, Z J Li, C C M Wong, H P S Wong, and Joseph J.Y. Sung
- Subjects
medicine.medical_treatment ,Genetic Vectors ,Interleukin-1beta ,Gene Expression ,Apoptosis ,Inflammation ,Biology ,Cathelicidin ,Mice ,Immune system ,Administration, Rectal ,Cathelicidins ,Genetics ,medicine ,Animals ,Intestinal Mucosa ,Colitis ,Molecular Biology ,Peroxidase ,Mice, Knockout ,Tumor Necrosis Factor-alpha ,Mucin ,Mucins ,Genetic Therapy ,medicine.disease ,Ulcerative colitis ,Mucus ,Immunology ,Molecular Medicine ,Colitis, Ulcerative ,lipids (amino acids, peptides, and proteins) ,Tumor necrosis factor alpha ,medicine.symptom ,Antimicrobial Cationic Peptides ,Plasmids - Abstract
Cathelicidin is a pleiotropic host defense peptide secreted by epithelial and immune cells. Whether endogenous cathelicidin is protective against ulcerative colitis, however, is unclear. Here we sought to delineate the role of endogenous murine cathelicidin (mCRAMP) and the therapeutic efficacy of intrarectal administration of mCRAMP-encoding plasmid in ulcerative colitis using dextran sulfate sodium (DSS)-challenged cathelicidin-knockout (Cnlp(-/-)) mice as a model. Cnlp(-/-) mice had more severe symptoms and mucosal disruption than the wild-type mice in response to DSS challenge. The tissue levels of interleukin-1β and tumor necrosis factor-α, myeloperoxidase activity and the number of apoptotic cells were increased in the colon of DSS-challenged Cnlp(-/-) mice. Moreover, mucus secretion and mucin gene expression were impaired in Cnlp(-/-) mice. All these abnormalities were reversed by the intrarectal administration of mCRAMP or mCRAMP-encoding plasmid. Taken together, endogenous cathelicidin may protect against ulcerative colitis through modulation of inflammation and mucus secretion.
- Published
- 2012
70. Prevalence of pre-sarcopenia and sarcopenia in Hong Kong Chinese geriatric patients with hip fracture and its correlation with different factors
- Author
-
A Wh, Ho, M Ml, Lee, E Wc, Chan, H My, Ng, C W, Lee, W S, Ng, and S H, Wong
- Subjects
Male ,medicine.medical_specialty ,Sarcopenia ,Osteoporosis ,Statistics as Topic ,Poison control ,Body Mass Index ,Grip strength ,Absorptiometry, Photon ,medicine ,Prevalence ,Humans ,Aged ,Aged, 80 and over ,Hip fracture ,Hand Strength ,business.industry ,Hip Fractures ,Body Weight ,General Medicine ,medicine.disease ,Body Height ,medicine.anatomical_structure ,Hip bone ,Lean body mass ,Physical therapy ,Body Composition ,Hong Kong ,Female ,Medical emergency ,business ,human activities ,Body mass index - Abstract
Introduction Sarcopenia and osteoporosis are age-related declines in the quantity of muscle and bone, respectively. Both contribute in disability, fall, and hip fracture in the elderly. This study reported the prevalence of sarcopenia in Chinese geriatric patients with hip fracture, and the correlation between relative appendicular skeletal muscle mass index and other factors. Methods This case series was conducted in Kowloon West Cluster Orthopaedic Rehabilitation Centre in Hong Kong. Data of all geriatric patients with primary hip fracture admitted to the above Centre from June to December 2014 were studied. Isometric grip strength, the maximal handgrip strength, was measured using a JAMAR hand dynamometer. Body composition including appendicular and whole-body lean body mass was measured using dual-energy X-ray absorptiometry. Pearson's correlation was used to examine the correlation between relative appendicular skeletal muscle mass index and other factors. Results A total of 239 patients with a mean age of 82 years were included in the study. Stratifying patients as male or female, the mean (± standard deviation) hand grip strength was 20.6 ± 7.3 kg and 13.6 ± 4.5 kg, the mean relative appendicular skeletal muscle mass index was 5.72 ± 0.83 kg/m(2) and 4.87 ± 0.83 kg/m(2), and the mean hip bone mineral density was 0.696 ± 0.13 g/cm(2) and 0.622 ± 0.12 g/cm(2), respectively. The prevalence of sarcopenia based on relative appendicular skeletal muscle mass index and hand grip strength according to the Asian Working Group for Sarcopenia definition was 73.6% in males and 67.7% in females. According to the European Working Group on Sarcopenia definition, the prevalence of pre-sarcopenia was 20.8% in males and 12.4% in females. Relative appendicular skeletal muscle mass index was positively correlated with hand grip strength, body weight, hip bone mineral density, body mass index, and total fat mass in males; and hand grip strength, body weight, body height, body mass index, and total fat mass in females. Except for body height in females, all correlations were statistically significant. Conclusion The prevalence of sarcopenia was very high in geriatric hip fracture patients, and much higher than that in community-dwelling elderly population. Apart from the need to prescribe osteoporosis medicine, sarcopenia screening and treatment should be offered and is essential to reduce subsequent fall, subsequent fracture, fracture-related complications and economic burden to Hong Kong.
- Published
- 2015
71. Hypertension impairs hippocampus-related adult neurogenesis, CA1 neuron dendritic arborization and long-term memory
- Author
-
Yao Hsiang Shih, S. F. Tsai, T. T. Yang, Y. T. Chiang, Yu Min Kuo, S. H. Huang, C. W. Lee, Michael W. Hughes, and Shih-Ying Wu
- Subjects
0301 basic medicine ,Male ,medicine.medical_specialty ,Memory, Long-Term ,Neurogenesis ,Hippocampus ,Hippocampal formation ,Renal Artery Obstruction ,03 medical and health sciences ,0302 clinical medicine ,Neurotrophic factors ,Internal medicine ,medicine ,Animals ,Maze Learning ,Brain-derived neurotrophic factor ,Neurons ,Mice, Inbred C3H ,Microglia ,Long-term memory ,General Neuroscience ,Brain-Derived Neurotrophic Factor ,Recognition, Psychology ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,medicine.anatomical_structure ,Endocrinology ,Memory, Short-Term ,Astrocytes ,Hypertension ,Psychology ,Neuroscience ,030217 neurology & neurosurgery ,Blood vessel - Abstract
Hypertension is associated with neurodegenerative diseases and cognitive impairment. Several studies using spontaneous hypertensive rats to study the effect of hypertension on memory performance and adult hippocampal neurogenesis have reached inconsistent conclusions. The contradictory findings may be related to the genetic variability of spontaneous hypertensive rats due to the conventional breeding practices. The objective of this study is to examine the effect of hypertension on hippocampal structure and function in isogenic mice. Hypertension was induced by the '2 kidneys, 1 clip' method (2K1C) which constricted one of the two renal arteries. The blood pressures of 2K1C mice were higher than the sham group on post-operation day 7 and remained high up to day 28. Mice with 2K1C-induced hypertension had impaired long-term, but not short-term, memory. Dendritic complexity of CA1 neurons and hippocampal neurogenesis were reduced by 2K1C-induced hypertension on post-operation day 28. Furthermore, 2K1C decreased the levels of hippocampal brain-derived neurotrophic factor, while blood vessel density and activation status of astrocytes and microglia were not affected. In conclusion, hypertension impairs hippocampus-associated long-term memory, dendritic arborization and neurogenesis, which may be caused by down-regulation of brain-derived neurotrophic factor signaling pathways.
- Published
- 2015
72. Bayesian Forecasting for Financial Risk Management, Pre and Post the Global Financial Crisis
- Author
-
W. C. W. Lee, Richard Gerlach, Cathy W. S. Chen, and Edward M.H. Lin
- Subjects
Stochastic volatility ,Markov chain ,Financial economics ,Strategy and Management ,Autoregressive conditional heteroskedasticity ,Bayesian probability ,Financial risk management ,Markov chain Monte Carlo ,Management Science and Operations Research ,Computer Science Applications ,symbols.namesake ,Modeling and Simulation ,symbols ,Econometrics ,Statistics, Probability and Uncertainty ,Volatility (finance) ,Value at risk ,Mathematics - Abstract
Value-at-risk (VaR) forecasting via a computational Bayesian framework is considered. A range of parametric models is compared, including standard, threshold nonlinear and Markov switching generalized autoregressive conditional heteroskedasticity (GARCH) specifications, plus standard and nonlinear stochastic volatility models, most considering four error probability distributions: Gaussian, Student-t, skewed-t and generalized error distribution. Adaptive Markov chain Monte Carlo methods are employed in estimation and forecasting. A portfolio of four Asia–Pacific stock markets is considered. Two forecasting periods are evaluated in light of the recent global financial crisis. Results reveal that: (i) GARCH models outperformed stochastic volatility models in almost all cases; (ii) asymmetric volatility models were clearly favoured pre crisis, while at the 1% level during and post crisis, for a 1-day horizon, models with skewed-t errors ranked best, while integrated GARCH models were favoured at the 5% level; (iii) all models forecast VaR less accurately and anti-conservatively post crisis. Copyright © 2011 John Wiley & Sons, Ltd.
- Published
- 2011
73. Motor noise generation and prediction for high spinning speed hard disk drive
- Author
-
Jianqiang Mou, F. Gao, H. N. Phyu, W. Z. Lin, Eng Hong Ong, and C. W. Lee
- Subjects
Engineering ,business.industry ,Voice coil ,Condensed Matter Physics ,Sound power ,DC motor ,Automotive engineering ,Electronic, Optical and Magnetic Materials ,Noise ,Hardware and Architecture ,Phase noise ,Electronic engineering ,Torque ,Torque ripple ,Electrical and Electronic Engineering ,business ,Structural acoustics - Abstract
The acoustic level of a hard disk drive is an important specification. This is especially so for enterprise HDD which is required to operate under a high spinning speed. In order to reduce the acoustics level of a HDD, an in depth understanding behind the mechanisms whereby the noise is being generated in a HDD should be established. This paper will study the acoustics characteristics of a high speed permanent magnet brushless DC motor (PM BLDC) and investigate the physics underlying the generation of noise associated with a motor. An analysis procedure of the PM BLDC motor noise generating mechanisms is proposed. Through finite element analysis and experimental verification, the results indicate that the major noise source for the high speed PM BLDC motor is due to the presence of electromagnetic (EM) torque ripples. Furthermore, it has been observed that the noise radiated by a HDD can be amplified when its structural dynamics are close to the frequency components of the noise source. Finally, a methodology which discusses the steps involved in the prediction of motor radiated noise will be presented.
- Published
- 2011
74. Effects of Panax ginseng on Tumor Necrosis Factor-α-Mediated Inflammation: A Mini-Review
- Author
-
Davy C. W. Lee and Allan S. Y. Lau
- Subjects
Chemokine ,Panax ,Pharmaceutical Science ,Inflammation ,Review ,Pharmacology ,immunomodulation ,complex mixtures ,Cell Line ,Analytical Chemistry ,Nitric oxide ,Proinflammatory cytokine ,lcsh:QD241-441 ,Mice ,chemistry.chemical_compound ,Ginseng ,lcsh:Organic chemistry ,Drug Discovery ,medicine ,Animals ,Physical and Theoretical Chemistry ,ginsenosides ,biology ,Plant Extracts ,Tumor Necrosis Factor-alpha ,Kinase ,business.industry ,Organic Chemistry ,Panax ginseng ,cytokines ,Nitric oxide synthase ,chemistry ,inflammation ,Chemistry (miscellaneous) ,biology.protein ,Molecular Medicine ,Tumor necrosis factor alpha ,medicine.symptom ,business - Abstract
Panax ginseng is one of the most commonly used Chinese medicines in China, Asia and Western countries. The beneficial effects of ginseng have been attributed to the biological activities of its constituents, the ginsenosides. In this review, we summarize recent publications on the anti-inflammatory effects of ginseng extracts and ginsenosides on cellular responses triggered by different inducers including endotoxin, tumor necrosis factor-alpha (TNF-α), interferon-gamma and other stimuli. Proinflammatory cytokines, chemokines, adhesion molecules and mediators of inflammation including inducible nitric oxide synthase, cyclooxygenase-2 and nitric oxide orchestrate the inflammatory response. Ginseng extracts and ginsenosides including Rb₁, Rd, Rg₁, Rg₃, Rh₁, Rh₂, Rh₃ and Rp₁ have been reported to have anti-inflammatory properties in different studies related to inflammation. Ginsenosides inhibit different inducers-activated signaling protein kinases and transcription factor nuclear factor-kappaB leading to decreases in the production of cytokines and mediators of inflammation. The therapeutic potential of ginseng on TNF-α-mediated inflammatory diseases is also discussed. Taken together, this summary provides evidences for the anti-inflammatory effects of ginseng extracts and ginsenosides as well as the underlying mechanisms of their effects on inflammatory diseases.
- Published
- 2011
75. Abstract 3542: Missense mutations in USE1 promote lung tumorigenesis
- Author
-
Peter C. W. Lee
- Subjects
Cancer Research ,Lung ,medicine.anatomical_structure ,Oncology ,USE1 ,Cancer research ,medicine ,Missense mutation ,Biology ,Carcinogenesis ,medicine.disease_cause - Abstract
The UBA6-USE1 enzyme cascade is a poorly characterized arm of the ubiquitin-proteasome system. We found that UBA6 and USE1 proteins are frequently overexpressed in lung cancer patients (83.01% and 92.45%, respectively; n = 106). Stable overexpression of UBA6 or USE1 significantly increased cell proliferation, migration, and invasiveness in lung cancer cells and xenograft models, whereas their knockdown significantly reduced cell proliferation, migration, and invasion. USE1 has a conserved D-box domain and the level of the protein was regulated by the anaphase-promoting complex through its interaction with CDC20 and CDH1. Furthermore, several missense mutations in USE1 identified in patients prolong the half-life and stability of the protein. Our findings reveal novel roles for USE1 in lung cancer and the possible use of USE1 as a novel biomarker and therapeutic target for lung cancer treatment. Citation Format: Peter C. W. Lee. Missense mutations in USE1 promote lung tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3542.
- Published
- 2018
76. Identification of Sulfur- and Nitrogen-containing Organic Species in the Extracts from Pocahontas No. 3 Coal
- Author
-
Longhao Sun, Jing-Pei Cao, X.-Y. Wei, Wei Zhao, C. W. Lee, Xinglong Zhao, and Zhi-Min Zong
- Subjects
Renewable Energy, Sustainability and the Environment ,Carbazole ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Sulfur ,Solvent ,chemistry.chemical_compound ,Fuel Technology ,Nuclear Energy and Engineering ,chemistry ,Dibenzothiophene ,Acetone ,Organic chemistry ,Gas chromatography ,Methanol ,Benzene - Abstract
Pocahontas No. 3 coal was extracted with CS2, n-hexane, benzene, methanol, acetone, and acetone/CS2 (1:1 vol/vol) mixed solvent sequentially. The resulting six extracts were analyzed with gas chromatography/mass spectrometer (GC/MS). Hexathiane, octathiocane, 23 sulfur-containing organic species, and 21 nitrogen-containing organic species were detected in the extracts. Sulfur-containing organic species detected in the extracts include dialkyl- and disulfides, dimexano, dibenzothiophene, benzonaphthothiophene, and their methyl-derivatives, among which dimexano and dixanthogen were seldom reported in any sediments. Methanol is effective for extracting sulfur-containing organic species without aromatic ring. Most of the nitrogen-containing organic species detected in the extracts are acridinone, carbazole and their methyl-derivatives, benzocarbazoles, amines, phenanthridinone, and piperidinone. The species number of nitrogen-containing organic compounds detected in the extracts increased with the in...
- Published
- 2010
77. Predictions of the effects of piston-liner crevices on flow motion and emissions in three-dimensional diesel engine simulations
- Author
-
Rolf D. Reitz and C-W Lee
- Subjects
Meteorology ,Chemistry ,Mechanical Engineering ,Flow (psychology) ,Aerospace Engineering ,Ocean Engineering ,Mechanics ,Diesel engine ,Vortex ,law.invention ,Piston ,law ,Automotive Engineering ,Fluid dynamics ,Squish ,Stroke (engine) ,Combustion chamber - Abstract
Computational fluid dynamics predictions of the flow field and pollutant emissions in a high-speed direct-injection diesel engine operating at high load and rated speed are presented. Piston-liner crevice flows during the expansion stroke can give rise to vortex motions whose characteristics depend on the piston crevice configuration. Both a realistic and a simplified crevice volume that consists of a neck area and a reservoir to keep the surface—volume ratio realistic are considered. In the simplified crevice approach, with moderate intensity of the crevice flow, the vortex enhances mixing and engine-out carbon monoxide (CO) emissions are reduced. However, when the crevice flow intensity is above a certain level, a strong tumble motion is created in the bulk mixture in the squish area, which isolates a region of high CO concentration and prevents oxidation. The results also show that proper timing of the crevice flow into the combustion chamber lowers the mixture temperature and reduces nitrogen oxide emissions. Calculations with a realistic crevice flow geometry and a crevice flow submodel also predict squish region vortex motion.
- Published
- 2009
78. Isolation and characterization of culturable bacteria from tropical coastal waters
- Author
-
C-W Lee, Kumaran Narayanan, A Y-F Ng, E U-H Sim, and C-C Ng
- Subjects
biology ,Botany ,Aquatic Science ,biology.organism_classification ,Isolation (microbiology) ,Bacteria - Abstract
In this study we isolated and characterized some culturable bacteria from tropical coastal waters of Peninsular Malaysia. We obtained between 0.23 and 1.85 × 103 cfu mL–1 in the Zobell 2216E medium, and cultured 0.04% to 0.12% of total bacterial counts. Different bacterial strains were then selected by 16S rDNA RFLP using four restriction enzymes (DdeI, HhaI, RsaI, and Sau3AI), of which HhaI gave the most RFLP patterns. A total of 54 unique strains were obtained and these were identified by their 16S rDNA gene sequence. These bacterial strains could be divided into five classes: 38 strains of γ-Proteobacteria (61.1%); 3 strains of α-Proteobacteria (5.5%); 2 strains of the Cytophaga-Flavobacterium-Bacteroides group (3.7%); 3 strains of high GC, Gram-positive bacteria (5.5%); and 13 strains of low GC, Gram-positive bacteria (24.1%). These isolates have good potential for further biotechnological studies since about 56% of the isolates exhibited amylase activity, whereas 36% and 18% of the isolates had protease and lipase, respectively. Most (>70%) of the isolates also produced poly-ß-hydroxybutyrate.
- Published
- 2009
79. A study on the efficiency of the DAF (dissolved air flotation) process using ozone injection
- Author
-
S. W. Yoo, L. S. Kang, H. K. Yeom, and C. W. Lee
- Subjects
chemistry.chemical_classification ,Ozone ,Chemistry ,Dissolved air flotation ,Environmental engineering ,Mixing (process engineering) ,Turbidite ,chemistry.chemical_compound ,Impeller ,Environmental chemistry ,Water treatment ,Organic matter ,Turbidity ,Water Science and Technology - Abstract
In this study, dissolved ozone flotation system with injecting ozone directly into a DAF pump developed was applied to remove turbidity and organic matter for water treatment. This ozone flotation system was evaluated on the basis of the efficiency of ozone transfer into water and the removal efficiency of turbidity and TOC in the Nakdong river water. The DAF pump system found to be more efficient than the conventional DAF system injecting ozone directly from a ozone generator. The ozone through the DAF pump process was dissolved in water much faster than through the general ozone generator due to the higher mixing efficiency through a pump impeller and high pressure inside the DAF pump. Also, the kinetics of ozone decay injected by the DAF pump was slower than injected by an ozone generator. The DAF pump flotation system shows that 30% difference of removal efficiencies is attained as the ozone dose increases from 1.2 mg/L to 8.2 mg/L. And the turbidity removal was increased with increasing ozone dose. Therefore it can be concluded that ozone in this flotation system facilitates improved removal of organic matter and turbidity due to enhanced destabilization of those.
- Published
- 2009
80. HIV-1 transactivator protein induction of suppressor of cytokine signaling-2 contributes to dysregulation of IFNγ signaling
- Author
-
Sherman M. Cheng, Allan S. Y. Lau, San San Lin, Davy C. W. Lee, Zhiwei Chen, Li Liu, and James C. B. Li
- Subjects
Transcriptional Activation ,medicine.medical_treatment ,Immunology ,Suppressor of Cytokine Signaling Proteins ,Biology ,Biochemistry ,Monocytes ,Interferon-gamma ,Transactivation ,medicine ,Humans ,Interferon gamma ,STAT1 ,SOCS2 ,Cells, Cultured ,Suppressor of cytokine signaling 1 ,Immunity ,Cell Biology ,Hematology ,Cell biology ,STAT1 Transcription Factor ,Cytokine ,HIV-1 ,biology.protein ,Phosphorylation ,tat Gene Products, Human Immunodeficiency Virus ,Signal transduction ,Signal Transduction ,medicine.drug - Abstract
HIV infection remains a worldwide threat. HIV-1 transactivator protein Tat is one of the retroviral proteins identified as a key immunomodulator in AIDS pathogenesis. Although the primary function of Tat is to regulate HIV-1 replication in the infected cell, it also dysregulates cytokine production resulting in perturbation of the host immune response and enhancement of the retrovirus survival. Because interferon-γ (IFNγ) is a pleiotropic cytokine with potent antiviral and immunoregulatory effects, we investigated whether Tat interferes with the IFNγ signal transduction in primary monocytes. We demonstrated that Tat impaired the IFNγ-receptor signaling pathway at the level of STAT1 activation, possibly via Tat-dependent induction of suppressor of cytokine signaling-2 (SOCS-2) activity. We delineated the inhibitory role of SOCS-2 in IFNγ signaling pathway by overexpression of exogenous SOCS-2 in HEK293 cell. The results showed that SOCS-2 suppressed the IFNγ-activated STAT1 phosphorylation and consequent IFNγ-regulated transcription of specific genes. To confirm the role of SOCS2 in the Tat-induced process, we demonstrated that SOCS-2 siRNA in human blood monocytes abrogated the Tat-dependent inhibition of IFNγ signaling. Our data suggested a possible mechanism implicating the role of SOCS-2 in mediating HIV-1–induced immune evasion and dysregulation of IFNγ signaling in primary human monocytes.
- Published
- 2009
81. A Novel Small-Molecule Inhibitor of the Avian Influenza H5N1 Virus Determined through Computational Screening against the Neuraminidase
- Author
-
Allan S. Y. Lau, Jianghong An, Cindy L.H. Yang, Leo L.M. Poon, Steven J.M. Jones, Davy C. W. Lee, and Anna H. Y. Law
- Subjects
Models, Molecular ,Oseltamivir ,medicine.drug_class ,viruses ,Orthomyxoviridae ,Drug Evaluation, Preclinical ,Molecular Conformation ,Neuraminidase ,medicine.disease_cause ,Antiviral Agents ,Cell Line ,Birds ,Small Molecule Libraries ,chemistry.chemical_compound ,Influenza A Virus, H1N1 Subtype ,Zanamivir ,Drug Discovery ,medicine ,Influenza A virus ,Animals ,Humans ,Computer Simulation ,Influenza A Virus, H5N1 Subtype ,Neuraminidase inhibitor ,biology ,Computational Biology ,Reproducibility of Results ,virus diseases ,biology.organism_classification ,Small molecule ,Virology ,respiratory tract diseases ,Pyrimidines ,chemistry ,Biochemistry ,Viral replication ,Influenza in Birds ,biology.protein ,Molecular Medicine ,medicine.drug - Abstract
Computational molecular docking provides an efficient and innovative approach to examine small molecule and protein interactions. We have utilized this method to identify potential inhibitors of the H5N1 neuraminidase protein. Of the 20 compounds tested, 4-(4-((3-(2-amino-4-hydroxy-6-methyl-5-pyrimidinyl)propyl)amino)phenyl)-1-chloro-3-buten-2-one (1) (NSC89853) demonstrated the ability to inhibit viral replication at a level comparable to the known neuraminidase inhibitor oseltamivir. Compound 1 demonstrated efficacy across a number of cell-lines assays and in both the H1N1 and H5N1 viruses. The predicted binding of 1 to the known H5N1 neuraminidase structure indicates a binding interface largely nonoverlapping with that of oseltamivir or another neuraminidase inhibitor zanamivir. These results indicate that 1 or similar molecules would remain effective in the presence of virus mutations conferring resistance to either oseltamivir or zanamivir and also vice versa.
- Published
- 2009
82. The radioactivity analysis of14C and3H in graphite from the dismantled korea research reactor and its dose estimation
- Author
-
W. Lee, C. W. Lee, G. S. Choi, S. B. Hong, G. H. Chung, and Hee Reyoung Kim
- Subjects
Radionuclide ,Renewable Energy, Sustainability and the Environment ,business.industry ,Health, Toxicology and Mutagenesis ,Radiochemistry ,Public Health, Environmental and Occupational Health ,Radioactive waste ,Combustion ,Effective dose (radiation) ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Nitric acid ,Sample preparation ,Tritium ,Graphite ,Safety, Risk, Reliability and Quality ,Nuclear medicine ,business ,Waste Management and Disposal - Abstract
A high temperature combustion method was used to analyze the 14 C and 3 H activities in graphite and the dose assessment was carried out to determine the clearance in the conservative way. By this method, the 3 H and 14 C were simultaneously trapped in the nitric acid and carbosorb, respectively. Accordingly, the sample preparation time for the measurement was reduced to the half. The combustion temperature was more than 800 degrees in centigrade for obtaining total tritium and 14 C in the sample. The combustion ratio was about 99% on the graphite sample with the weight of 0.1 g. Minimum detectable activity was 0.05 Bq/g for the 14 C and 0.15 Bq/g for the 3 H at the same background counting time. The recoveries from the combustion furnace were around 100% and 90% in 14 C and 3 H, respectively. The radioactivity were 2,530 ~ 3,160 Bq/g in 14 C and 1,700 ~2,040 Bq/g in 3 H at this experiment. The experimental uncertainty was less than 6% in both radionuclides where the furnace recovery was dominant factor. An individual effective dose from beta and gamma radionuclides was estimated by consideration of the scenario of inhalation, ingestion and external exposure. 60 Co, the radioactivity of which was measured by using HPGe detector, had a predominant effect in estimating the effective dose. The estimation showed that the graphite wastes from the dismantled research reactor should be disposed of as a low level radioactive waste rather than clearance.
- Published
- 2009
83. Green emitting polyhedral oligomeric silsesquioxanes / poly(phenylene vinylene) derivative materials for highly efficient organic light emitting diodes (OLEDs)
- Author
-
C. W. Lee, Y. Josse, T. P. Nguyen, Chain-Shu Hsu, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), and Université de Nantes (UN)-Université de Nantes (UN)
- Subjects
chemistry.chemical_classification ,Organic electronics ,Materials science ,Infrared spectroscopy ,02 engineering and technology ,Polymer ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Chemical engineering ,Phenylene ,Polymer chemistry ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,OLED ,Thin film ,0210 nano-technology ,Hybrid material ,Instrumentation ,ComputingMilieux_MISCELLANEOUS - Abstract
Hybrid materials composed of polyhedral oligomeric silsesquioxanes (POSS) and a polyphenylene vinylene (PPV) derivative were fabricated and characterized by optical and surface spectroscopy. The hybrid thin films have similar optical properties as the pristine polymer but contributions of the POSS are evidenced in infrared spectroscopy. Organic light emitting diodes using the hybrid material as an emitter clearly showed an improvement of the electrical characteristics and the efficiency of the devices as compared to those using the pristine polymer. The effects of POSS incorporation to the polymer are discussed via the obtained results.
- Published
- 2008
84. On the dominating set polytope
- Author
-
T. M. Contenza, Ali Ridha Mahjoub, M. Bouchakour, and C. W. Lee
- Subjects
Discrete mathematics ,Birkhoff polytope ,Linear programming ,Uniform k 21 polytope ,Theoretical Computer Science ,Combinatorics ,Computational Theory and Mathematics ,Rectification ,Dominating set ,Mathematics::Metric Geometry ,Discrete Mathematics and Combinatorics ,Maximal independent set ,Geometry and Topology ,Ehrhart polynomial ,Vertex enumeration problem ,MathematicsofComputing_DISCRETEMATHEMATICS ,Mathematics - Abstract
In this paper, we study the dominating set polytope in the class of graphs that decompose by one-node cutsets where the pieces are cycles. We describe some classes of facets and procedures to construct facets of the polytope in that class of graphs, and establish some structural properties. As a consequence we obtain a complete description of the polytope by a system of inequalities when the graph is a cycle. We also show that the separation problem related to that system can be solved in polynomial time. This yields a polynomial time cutting plane algorithm for the minimum weight dominating set problem in that case. We further discuss the applications for the class of cactus graphs.
- Published
- 2008
85. Investigation on Resistive Memory Switching Mechanism of NiO
- Author
-
D. C. KIM, S. SEO, D.-S. SUH, R. JUNG, C. W. LEE, J. K. SHIN, I. K. YOO, I. G. BAEK, H. J. KIM, E. K. YIM, S. O. PARK, H. S. KIM, U-IN CHUNG, J. T. MOON, B. I. RYU, J.-S. KIM, and B. H. PARK
- Subjects
Materials science ,business.industry ,Non-blocking I/O ,Nanotechnology ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Resistive random-access memory ,Control and Systems Engineering ,Memory cell ,Resistive switching ,Materials Chemistry ,Ceramics and Composites ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Mechanism (sociology) ,Voltage - Abstract
Experimental investigations on the resistive memory switching in sub-micron sized NiO memory cell are presented to elucidate the resistive memory switching mechanism. The voltage or current-biased I-V measurements show that the resistive switching transitions can be regarded as the combination of a voltage-controlled negative differential resistance phenomenon and a current-controlled negative differential resistance phenomenon. Along with experimental observations of multiple resistance states, these indicate that the memory switching in NiO would come from the percolative formation and rupture of filamentary conducting paths. Pulse experiments further suggest that the memory switching would come from local domains inside filaments.
- Published
- 2007
86. Polydiacetylene-based selective NH3gas sensor using Sc2O3/GaN structures
- Author
-
Jihyun Kim, Fan Ren, Brent P. Gila, Dong June Ahn, C. R. Abernathy, C. W. Lee, Gil Sun Lee, Hak Jong Choi, and Steve Pearton
- Subjects
Analytical chemistry ,Surfaces and Interfaces ,Condensed Matter Physics ,Epitaxy ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Contact angle ,Ammonia ,chemistry.chemical_compound ,Template ,chemistry ,Chemisorption ,Materials Chemistry ,Sapphire ,Electrical and Electronic Engineering ,Selectivity ,Molecular beam epitaxy - Abstract
PDA(Polydiacetylene)-supramolecules were successfully immobilized on the surface of Sc2O3/GaN/Sapphire structures for use as selective NH3 gas sensors. The Sc2O3 was epitaxially grown on GaN/Sapphire templates by molecular beam epitaxy (MBE) to replace the non-uniform native Ga2O3. The GaN-based PDA gas sensors showed excellent selectivity for ammonia detection after the end-functional group was modified to respond to this specific gas species. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
- Published
- 2007
87. Differential onset of apoptosis in influenza A virus H5N1- and H1N1-infected human blood macrophages
- Author
-
Allan S. Y. Lau, Chris Ka Pun Mok, Malik Peiris, Davy C. W. Lee, and CY Cheung
- Subjects
Programmed cell death ,Orthomyxoviridae ,Apoptosis ,Collagen Type XI ,medicine.disease_cause ,Virus ,Proinflammatory cytokine ,Pathogenesis ,Influenza A Virus, H1N1 Subtype ,Virology ,Influenza, Human ,Influenza A virus ,medicine ,Animals ,Humans ,Macrophage ,Cells, Cultured ,Influenza A Virus, H5N1 Subtype ,biology ,Macrophages ,virus diseases ,biology.organism_classification ,Caspases ,Immunology - Abstract
Pathogenesis of the highly pathogenic avian influenza virus A/Hong Kong/483/97 (H5N1/97) remains to be investigated. It was demonstrated recently that H5N1 dysregulation of proinflammatory cytokines in human macrophages is a p38-kinase-dependent process. The results indicated that macrophages may play a role in disease severity. To investigate cellular responses to H5N1 infection further, apoptosis and its related pathways were studied in primary blood macrophages. Here, it is shown that the H5N1/97 virus triggered apoptosis, including caspases and PARP activation, in infected macrophages with a delayed onset compared with H1N1 counterparts. Similar results were also found in human macrophages infected by precursors of the H5N1/97 virus. Thus, these results showed that the delay in apoptosis onset in macrophages infected by H5N1/97 and its related precursor subtypes may be a means for the pathogens to have longer survival in the cells; this may contribute to the pathogenesis of H5N1 disease in humans.
- Published
- 2007
88. Avian influenza virus signaling: implications for the disease severity of H5N1 infection
- Author
-
Allan S. Y. Lau and Davy C. W. Lee
- Subjects
viruses ,virus diseases ,Virulence ,Hemagglutinin (influenza) ,MDA5 ,Cell Biology ,Biology ,medicine.disease_cause ,H5N1 genetic structure ,Virology ,Influenza A virus subtype H5N1 ,Virus ,Microbiology ,Viral replication ,Pandemic ,medicine ,biology.protein ,Molecular Biology - Abstract
The global outbreak of avian influenza virus infections in poultry and wild birds as well as the high mortality rate in patients infected with the viruses pose a worldwide alert to the risk of an emerging epidemic. Scientific data to date showed some strains of avian influenza viruses including H5N1 are capable of going through mutations to develop into a novel, pandemic strain of influenza virus. Recent research has advanced our knowledge of the biological behavior of the virus, its interactions with mammalian cells, downstream signal transduction pathways, and the antiviral immune responses. A better understanding of the virus-activated signaling pathways will provide new clues to delineate the mechanisms underlying the pathogenesis of avian influenza virus infection. Here, we reviewed the contributions of human and avian influenza virus virulence factors including hemagglutinin HA, RNA polymerase, and nonstructural protein NS1. We next discussed the interaction of the viruses with cellular factors including Toll-like receptor TLR, RIG-I/MDA5, signaling kinases including PKR, MAPK and PI3K, and transcription factors NF-κB and IRF. Finally, we commented on the role of apoptosis and caspase activation as important host defense mechanisms. Taken together, virus replication and its activated inflammation contribute to the severity of avian influenza infections.
- Published
- 2007
89. Numerical simulations of homogeneous charge compression ignition engines with high levels of residual gas
- Author
-
C-W Lee and Epaminondas Mastorakos
- Subjects
Physics ,Mechanical Engineering ,Homogeneous charge compression ignition ,Monte Carlo method ,Aerospace Engineering ,Ocean Engineering ,Residual ,Computational physics ,Hybrid Monte Carlo ,Automotive Engineering ,Dynamic Monte Carlo method ,Direct simulation Monte Carlo ,Kinetic Monte Carlo ,Monte Carlo molecular modeling - Abstract
In order to account for the effect of mixture inhomogeneity in HCCI engines utilizing high levels of residual gas and to estimate accurate initial conditions, a sequential numerical procedure was devised. A one-dimensional (1D) engine cycle simulation and a three-dimensional (3D) CFD analysis were used to calculate the residual gas overall level and its spatial distribution. A Monte-Carlo method for the probability density function (PDF) of the mass fraction and temperature, assuming negligible spatial inhomogeneity in the mean quantities but including finite small-scale fluctuations, was used to allow for micro-mixing in the evolution of the chemical reactions. The computational fluid dynamics (CFD) analysis confirmed that substantial scalar inhomogeneity persists up to top dead centre (TDC). The result from the procedure showed a close prediction of the pressure profile from the experiment. However, the u HC level is underpredicted, attributed to the assumed spatial homogeneity of the mean quantities in the Monte-Carlo simulation, which causes an overprediction of the scalar fluctuation decay. Parametric studies of the initial mixture inhomogeneity and turbulence timescale showed that they affect both the ignition timing and combustion duration. A comparison of three mixing models (IEM, modified Curl, and EIEM) showed that the EIEM model predicts a later ignition. The results suggested that accurate prediction of pollutant emission in HCCI engines with high levels of residual gas can be achieved only by a fully 3D calculation incorporating turbulence-chemistry interactions, although combustion phasing and duration can be predicted with adequate accuracy with a volume-averaged representation of the initial residual gas fluctuations.
- Published
- 2007
90. Evaluation of haemodynamic flow to the hip in patients with systemic lupus erythematosus
- Author
-
H J Kim, M J Shin, and C W Lee
- Subjects
Adult ,Systemic disease ,medicine.medical_specialty ,Rotation ,Immunology ,Pulsatile flow ,Hemodynamics ,Femoral head ,Rheumatology ,Ischemia ,immune system diseases ,Internal medicine ,medicine ,Humans ,Lupus Erythematosus, Systemic ,Immunology and Allergy ,Circumflex ,skin and connective tissue diseases ,Lupus erythematosus ,business.industry ,Ultrasound ,Femur Head ,Ultrasonography, Doppler ,General Medicine ,Middle Aged ,medicine.disease ,Connective tissue disease ,Surgery ,medicine.anatomical_structure ,Regional Blood Flow ,Pulsatile Flow ,Cardiology ,Female ,Hip Joint ,business ,Blood Flow Velocity - Abstract
One of the groups with high risk for osteonecrosis is patients with systemic lupus erythematosus (SLE). No predictive test, however, is known to detect osteonecrosis. The purpose of this study was to evaluate haemodynamic flow to the proximal femur in SLE patients.Twenty-two SLE patients without osteonecrosis were evaluated in comparison with 15 healthy controls. Medial and lateral circumflex arteries of 44 hips in the 22 SLE patients and 30 hips in the healthy controls were examined using ultrasound equipment with colour and power Doppler capability. Arterial pulsatility index (PI) and peak systolic velocity (PSV) were determined with neutral and internal rotation positions (stimulated ischaemia).PSV was significantly increased in SLE patients compared to healthy controls in both the neutral position (70.6+/-40.4 vs. 46.9+/-19.3; p0.001) and after internal rotation of the femoral head (74.8+/-42.3 vs. 49.9+/-19.9; p0.001). PI was also higher in SLE patients than in healthy controls in both the neutral position (8.9+/-6.3 vs. 5.5+/-3.4; p0.001) and after internal rotation (8.1+/-7.1 vs. 3.9+/-2.4; p0.001).PSV and PI of arteries to the femur head in SLE patients were significantly higher than in healthy controls.
- Published
- 2007
91. Cylindroid Lamella-Particle Complexes and Nucleoid Intracytoplasmic Bodies in Lymphoma Cells of Northern Pike (Esox lucius)
- Author
-
C W Lee, W G Banfield, R Sonstegard, C J Dawe, and H J Michelitch
- Subjects
biology ,medicine ,Nucleoid ,Anatomy ,medicine.disease ,biology.organism_classification ,computer ,Molecular biology ,Esox ,Lymphoma ,Lamella (cell biology) ,Pike ,computer.programming_language - Published
- 2015
92. Menopausal hormone use and ovarian cancer risk: individual participant meta-analysis of 52 epidemiological studies
- Author
-
Gapstur, S. M. Patel, A. V. Banks, E. Dal Maso, L. and Talamini, R. Chetrit, A. Hirsh-Yechezkel, G. Lubin, F. and Sadetzki, S. Beral, V. Bull, D. Cairns, B. Crossley, B. and Gaitskell, K. Goodill, A. Green, J. Hermon, C. Key, T. Moser, K. Reeves, G. Sitas, F. Collins, R. Peto, R. Gonzalez, C. A. Lee, N. Marchbanks, P. Ory, H. W. and Peterson, H. B. Wingo, P. A. Martin, N. Silpisornkosol, S. and Theetranont, C. Boosiri, B. Chutivongse, S. Jimakorn, P. and Virutamasen, P. Wongsrichanalai, C. Goodman, M. T. and Lidegaard, O. Kjaer, S. K. Morch, L. S. Tjonneland, A. and Byers, T. Rohan, T. Mosgaard, B. Vessey, M. Yeates, D. and Freudenheim, J. L. Titus, L. J. Chang-Claude, J. Kaaks, R. Anderson, K. E. Lazovich, D. Robien, K. Hampton, J. and Newcomb, P. A. Rossing, M. A. Thomas, D. B. Weiss, N. S. and Lokkegaard, E. Riboli, E. Clavel-Chapelon, F. Cramer, D. and Hankinson, S. E. Tamimi, R. M. Tworoger, S. S. and Franceschi, S. La Vecchia, C. Negri, E. Adami, H. O. and Magnusson, C. Riman, T. Weiderpass, E. Wolk, A. and Schouten, L. J. van den Brandt, P. A. Chantarakul, N. and Koetsawang, S. Rachawat, D. Palli, D. Black, A. Brinton, L. A. Freedman, D. M. Hartge, P. Hsing, A. W. Jnr, J. V. Lacey Lissowska, J. Hoover, R. N. Schairer, C. Babb, C. and Urban, M. Graff-Iversen, S. Selmer, R. Bain, C. J. and Green, A. C. Purdie, D. M. Siskind, V. Webb, P. M. and Moysich, K. McCann, S. E. Hannaford, P. Kay, C. Binns, C. W. Lee, A. H. Zhang, M. Ness, R. B. Nasca, P. and Coogan, P. F. Palmer, J. R. Rosenberg, L. Whittemore, A. and Katsouyanni, K. Trichopoulou, A. Trichopoulos, D. Tzonou, A. and Dabancens, A. Martinez, L. Molina, R. Salas, O. and Lurie, G. Carney, M. E. Wilkens, L. R. Hartman, L. and Manjer, J. Olsson, H. Kumle, M. Grisso, J. A. Morgan, M. and Wheeler, J. E. Edwards, R. P. Kelley, J. L. Modugno, F. and Onland-Moret, N. C. Peeters, P. H. M. Casagrande, J. and Pike, M. C. Wu, A. H. Canfell, K. Miller, A. B. Gram, I. T. Lund, E. McGowan, L. Shu, X. O. Zheng, W. Farley, T. M. M. Holck, S. Meirik, O. Risch, H. A. Collaborative Grp Epidemiological
- Abstract
Background Half the epidemiological studies with information about menopausal hormone therapy and ovarian cancer risk remain unpublished, and some retrospective studies could have been biased by selective participation or recall. We aimed to assess with minimal bias the effects of hormone therapy on ovarian cancer risk. Methods Individual participant datasets from 52 epidemiological studies were analysed centrally. The principal analyses involved the prospective studies (with last hormone therapy use extrapolated forwards for up to 4 years). Sensitivity analyses included the retrospective studies. Adjusted Poisson regressions yielded relative risks (RRs) versus never-use. Findings During prospective follow-up, 12 110 postmenopausal women, 55% (6601) of whom had used hormone therapy, developed ovarian cancer. Among women last recorded as current users, risk was increased even with
- Published
- 2015
93. Ionic conductance of PDMAEMA/PEO polymeric electrolyte containing lithium salt mixed with plasticizer
- Author
-
Eun Hee Cha, C W Lee, Douglas R. MacFarlane, and S Lim
- Subjects
chemistry.chemical_classification ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Inorganic chemistry ,technology, industry, and agriculture ,Plasticizer ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Salt (chemistry) ,Electrolyte ,Dielectric spectroscopy ,Tetraethylene glycol dimethyl ether ,chemistry.chemical_compound ,Differential scanning calorimetry ,Chemical engineering ,Ionic conductivity ,Lithium ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry - Abstract
Novel plasticized polymer electrolytes were synthesized with poly(N,N-dimethylamino-ethyl-methacrylate) (PDMAEMA), polyethylene oxide (PEO), LiTFSI as a salt, tetraethylene glycol dimethyl ether (tetraglyme), EC/PC and DEP as plasticizers. The ionic conductivity of various compositions of polymer electrolytes was investigated as a function of temperature, various concentrations of LiTFSI, plasticizers and various ratio of PDMAEMA/PEO. The ionic conductivity of PDMAEMA/PEO/LiTFSI (1.5 mol kg−1) with DEP as a plasticizer (1.5 × 10−4 S cm−1) exhibited lower than PDMAEMA/PEO/LiTFSI (1.2 mol kg−1)/tetraglyme (5.24 × 10−4 S cm−1) and PDMAEMA/PEO/LiTFSI (1.5 mol kg−1)/EC + PC (2.1 × 10−4 S cm−1). As increasing the PDMAEMA concentration up to 13.3%, the ionic conductivity was decreased rapidly. As increasing the PDMAEMA concentration the ionic conductivity was decreased due to high viscosity and some interactions reducing ion pairing. These plasticized polymer electrolytes were characterized by impedance spectroscopy and DSC.
- Published
- 2006
94. Fast elliptic scalar multiplication using new double-base chain and point halving
- Author
-
Edward C. W. Lee, Lee-Ming Cheng, Xiaofeng Liao, and Kwok-Wo Wong
- Subjects
business.industry ,Applied Mathematics ,Computation ,Scalar (mathematics) ,Cryptography ,Scalar multiplication ,Topology ,Algebra ,Computational Mathematics ,Elliptic curve point multiplication ,Elliptic curve cryptosystem ,Elliptic curve cryptography ,business ,Mathematics - Abstract
The fast implementation of elliptic curve cryptosystems relies on the efficient computation of scalar multiplication. Based on the double-base chain representation of scalar using powers of 2 and 3, we propose a new representation with powers of 1/2 and 3 instead. Thus the efficient point halving operation can be incorporated in the new double-base chain to achieve fast scalar multiplication. Experimental results show that our approach leads to a lower complexity which contributes to the efficient implementation of elliptic curve cryptosystems.
- Published
- 2006
95. Regulation of survivin expression by IGF-1/mTOR signaling
- Author
-
Valentina Vaira, C W Lee, Lucia R. Languino, Dario C. Altieri, Silvano Bosari, and Hira Lal Goel
- Subjects
Male ,Cancer Research ,Small interfering RNA ,Transcription, Genetic ,RNA Stability ,Survivin ,Down-Regulation ,Apoptosis ,Biology ,medicine.disease_cause ,Inhibitor of Apoptosis Proteins ,Receptor, IGF Type 1 ,Mice ,Prostate cancer ,Tumor Cells, Cultured ,Genetics ,medicine ,Animals ,Humans ,Insulin-Like Growth Factor I ,RNA, Small Interfering ,Promoter Regions, Genetic ,neoplasms ,Molecular Biology ,PI3K/AKT/mTOR pathway ,Cell Proliferation ,Mice, Knockout ,Sirolimus ,Cell growth ,TOR Serine-Threonine Kinases ,Cell Cycle ,Prostatic Neoplasms ,Ribosomal Protein S6 Kinases, 70-kDa ,Cancer ,Cell cycle ,medicine.disease ,Neoplasm Proteins ,Gene Expression Regulation, Neoplastic ,Cancer research ,Carcinogenesis ,Microtubule-Associated Proteins ,Protein Kinases ,HeLa Cells ,Signal Transduction - Abstract
Survivin is a dual regulator of cell proliferation and cell viability overexpressed in most human tumors. Although strategies to lower survivin levels have been pursued for rational cancer therapy, the molecular circuitries controlling survivin expression in tumors have not been completely elucidated. Here, we show that stimulation with insulin-like growth factor-1 (IGF-1) results in increased survivin expression in prostate cancer cells. This response is independent of de novo gene transcription, changes in mRNA expression or modifications of survivin protein stability. Instead, IGF-1 induced persistence and translation of a pool of survivin mRNA, in a reaction abolished by the mTOR (mammalian target of rapamycin) inhibitor, rapamycin. Forced expression of the mTOR target p70S6K1 reproduced the increase in survivin expression in prostate cancer cells, whereas acute ablation of endogenous p70S6K1 by small interfering RNA downregulated survivin levels. Rapamycin, alone or in combination with suboptimal concentrations of taxol reduced survivin protein levels, and decreased viability of prostate cancer cells. Therefore, IGF-1/mTOR signaling elevates survivin in prostate cancer cells via rapid changes in mRNA translation. Antagonists of this pathway may be beneficial to lower an antiapoptotic threshold maintained by survivin in prostate cancer.
- Published
- 2006
96. Experimental Study on the Effect of SO2 on PCDD/F Emissions: Determination of the Importance of Gas-Phase versus Solid-Phase Reactions in PCDD/F Formation
- Author
-
Xiao-Dong Li, C. W. Lee, Shawn Ryan, Matt Clayton, Brian K. Gullett, and Abderrahmane Touati
- Subjects
Flue gas ,Persistent organic pollutant ,Polychlorinated Dibenzodioxins ,Municipal solid waste ,business.industry ,Incineration ,General Chemistry ,Cofiring ,Dibenzofurans, Polychlorinated ,Combustion ,Refuse Disposal ,chemistry.chemical_compound ,Coal ,chemistry ,Air Pollution ,Fly ash ,Environmental chemistry ,Sulfur Dioxide ,Environmental Chemistry ,Gases ,business ,Sulfur dioxide ,Benzofurans - Abstract
Cofiring coal in municipal solid waste incinerators (MSWls) has previously been reported to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) emissions due to increasing the flue gas SO2 concentration. The present study was focused on understanding the primary mechanism responsible for the suppressant effect of SO2 on total PCDD/F formation and toxic equivalent (TEQ) emissions. The addition of SO2, simulating the effect of coal addition on the flue gas composition, resulted in significant reductions in the TEQ emissions due to reactions involving SO2 in the postcombustion zone. However, emissions of total PCDDs/Fs, unlike the TEQ value, were dependent upon the Cl2 and SO2 injection temperatures due to increases in non-TEQ correlated isomers. The conversion of metal chlorides in the fly ash to sulfates, thus reducing the sites responsible for chlorination/oxidation reactions, was concluded to be the main suppressant mechanism; proposed reactions for copper and iron are presented. This mechanism was found to be independent of combustion conditions and could have prolonged effects on PCDD/F emissions from deposits formed with high flue gas S/Cl ratios.
- Published
- 2006
97. Physiological basis for antagonism induced by mixtures of quizalofop-ethyl and bromoxynil in maize (Zea mays)
- Author
-
C W Lee, J S Kim, B H Lee, J H Yu, and T J Won
- Subjects
Photosystem II ,Bromoxynil ,Acetyl-CoA carboxylase ,food and beverages ,Plant Science ,Hill reaction ,chemistry.chemical_compound ,Horticulture ,chemistry ,Agronomy ,Phloem transport ,Poaceae ,Phloem ,Antagonism ,Agronomy and Crop Science ,Ecology, Evolution, Behavior and Systematics - Abstract
Summary In this study, the physiological basis for antagonism induced by mixtures of quizalofop-ethyl and bromoxynil was investigated in maize seedlings. In sequential applications, antagonism was observed when bromoxynil was applied before quizalofop-ethyl or in a mixture with quizalofop-ethyl, but was minimal when bromoxynil was applied afterwards. The degree of antagonism differed with application rates of bromoxynil and with the timing of the treatment. When test herbicides were applied locally to the second leaf, the inhibition of photosystem II (PS-II) in the herbicide-treated leaf was higher with the mixture than with bromoxynil or quizalofop-ethyl alone. Subsequent growth of the untreated third leaf inhibited by quizalofop-ethyl alone then recovered, depending on the dose of bromoxynil. There was no evidence that bromoxynil affected absorption of quizalofop-ethyl. In local applications at different positions on the second leaf, antagonism was only observed when quizalofop-ethyl was applied to the distal part of the leaf and bromoxynil applied to the proximal part. The antagonism of bromoxynil + quizalofop-ethyl did not occur at the level of acetyl CoA carboxylase and Hill reaction, as revealed by in vitro assays. These results suggest that bromoxynil inhibits the phloem transport of quizalofop-ethyl and thus antagonises its whole-plant activity in maize.
- Published
- 2006
98. Thermomechanical Behavior of a Polyurethane Shape Memory Polymer Foam
- Author
-
C. W. Lee, Weimin Huang, and H. P. Teo
- Subjects
chemistry.chemical_compound ,Shape-memory polymer ,Materials science ,chemistry ,Mechanical Engineering ,Compression test ,General Materials Science ,Cell structure ,Composite material ,Compression (physics) ,Polyurethane - Abstract
Shape memory polymers (SMPs) have attracted great interest in recent years. The SMP foams are outstanding, owing to their high shape recovery ratio in compression. They can be used for, for instance, micro foldable vehicles, shape determination, and microtags. This article presents a study on the thermomechanical behavior of a polyurethane SMP foam, associated with these three applications. This includes four types of tests namely, compression test, free recovery test, constrained cooling test, and gripping test.
- Published
- 2006
99. Electromigration-induced UBM consumption and the resulting failure mechanisms in flip-chip solder joints
- Author
-
C. M. Tsai, Y. L. Lin, C. W. Lee, C. R. Kao, and Chia-Hsien Chang
- Subjects
Materials science ,Metallurgy ,Current crowding ,Condensed Matter Physics ,Microstructure ,Electromigration ,Electronic, Optical and Magnetic Materials ,Soldering ,Materials Chemistry ,Metallizing ,Electrical and Electronic Engineering ,Porosity ,Flip chip ,Eutectic system - Abstract
Eutectic PbSn flip chip solder joint was subjected to 5×103 A/cm2 current stressing at 150°C and 3.5 × 104 A/cm2 current stressing at 30°C. The under bump metallurgy (UBM) on the chip was sputtered Ni/Cu, and the substrate side was a thick Cu trace. It was shown through in-situ observation that the local temperature near the entrance of electrons from the Al interconnect to the solder became higher than the rest of the joint. The accelerated local Ni UBM consumption near the entrance was also observed. Once the Ni was consumed at a location, a porous structure formed, and the flow of the electrons was blocked there. It was found that the formation of the void and the formation of the porous structure were competing with each other. If the porous structure formed first, then the void would not be able to nucleate there. On the other hand, if the void could nucleate before the UBM above lost its conductivity, then the joint would fail by the void formation-and-propagation mechanism.
- Published
- 2006
100. Proteomic analysis of differential protein expression in atherosclerosis
- Author
-
Y. S. Ryang, Ho Joong Sung, K. H. Han, Jesang Ko, Sung Wuk Jang, and C. W. Lee
- Subjects
Proteomics ,Health, Toxicology and Mutagenesis ,Clinical Biochemistry ,Aortic Diseases ,Inflammation ,Biology ,Matrix metalloproteinase ,Biochemistry ,Pathogenesis ,Western blot ,medicine ,Humans ,Electrophoresis, Gel, Two-Dimensional ,Regulation of gene expression ,medicine.diagnostic_test ,Proteins ,Atherosclerosis ,Cell biology ,Gene Expression Regulation ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Immunology ,Proteome ,medicine.symptom ,Signal transduction ,Signal Transduction - Abstract
Although recent studies have shown that several pro-inflammatory proteins can be used as biomarkers for atherosclerosis, the mechanism of atherogenesis is unclear and little information is available regarding proteins involved in development of the disease. Atherosclerotic tissue samples were collected from patients in order to identify the proteins involved in atherogenesis. The protein expression profile of atherosclerosis patients was analysed using two-dimensional electrophoresis-based proteomics. Thirty-nine proteins were detected that were differentially expressed in the atherosclerotic aorta compared with the normal aorta. Twenty-seven of these proteins were identified in the MS-FIT database. They are involved in a number of biological processes, including calcium-mediated processes, migration of vascular smooth muscle cells, matrix metalloproteinase activation and regulation of pro-inflammatory cytokines. Confirmation of differential protein expression was performed by Western blot analysis. Potential applications of the results include the identification and characterization of signalling pathways involved in atherogenesis, and further exploration of the role of selected identified proteins in atherosclerosis.
- Published
- 2006
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.