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Search Results: 1 - 10 of 86995 matches for " W. Zhuang "
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Cell cycle arrest in Metformin treated breast cancer cells involves activation of AMPK, downregulation of cyclin D1, and requires p27Kip1 or p21Cip1
Yongxian Zhuang, W Keith Miskimins
Journal of Molecular Signaling , 2008, DOI: 10.1186/1750-2187-3-18
Abstract: In this study, metformin was found to inhibit proliferation of most cultured breast cancer cell lines. This was independent of estrogen receptor, HER2, or p53 status. Inhibition of cell proliferation was associated with arrest within G0/G1 phase of the cell cycle. As in previous studies, metformin treatment led to activation of (AMPK) and downregulation of cyclin D1. However, these events were not sufficient for cell cycle arrest because they were also observed in the MDA-MB-231 cell line, which is not sensitive to growth arrest by metformin. In sensitive breast cancer lines, the reduction in cyclin D1 led to release of sequestered CDK inhibitors, p27Kip1 and p21Cip1, and association of these inhibitors with cyclin E/CDK2 complexes. The metformin-resistant cell line MDA-MB-231 expresses significantly lower levels of p27Kip1 and p21Cip1 than the metformin-sensitive cell line, MCF7. When p27Kip1 or p21Cip1 were overexpressed in MDA-MB-231, the cells became sensitive to cell cycle arrest in response to metformin.Cell cycle arrest in response to metformin requires CDK inhibitors in addition to AMPK activation and cyclin D1 downregulation. This is of interest because many cancers are associated with loss or downregulation of CDK inhibitors and the results may be relevant to the development of anti-tumor reagents that target the AMPK pathway.Metformin hydrochloride (N, N-dimethylimidodicarbonimidic diamide hydrochloride) is a commonly prescribed oral antihyperglycemic drug used in the management of Type 2 diabetes. Recent evidence indicates that metformin has significant effects on tumorigenesis and cancer cell growth. It was reported that patients with Type 2 diabetes who are prescribed metformin have a lower risk of cancer compared to patients that do not take metformin [1,2]. In a mouse xenograft model, metformin suppressed tumor growth of p53 negative HCT116 colon cancer cells, but not of p53 wild-type cells [3]. Metformin treatment decreases the incidence and size of
Comparative study of the in vitro and in vivo characteristics of cationic and neutral liposomes
Zhao W, Zhuang S, Qi XR
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S25399
Abstract: mparative study of the in vitro and in vivo characteristics of cationic and neutral liposomes Original Research (4113) Total Article Views Authors: Zhao W, Zhuang S, Qi XR Published Date December 2011 Volume 2011:6 Pages 3087 - 3098 DOI: http://dx.doi.org/10.2147/IJN.S25399 Wei Zhao, Song Zhuang, Xian-Rong Qi Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing, People's Republic of China Abstract: Neutral liposomes (NLP) exhibit preferential localization in solid tumors based on the enhanced permeation and retention (EPR) effect. Cationic liposomes (CLP) have a propensity for localizing in newly formed tumor vessels and they have a potentially enhanced antitumor effect. However, an increased amount of cationic lipids in liposomes also induces aggregation through electrostatic interactions between the liposomes and the anionic species in the circulation, which results in a reduced EPR effect. Consequently, it is important to investigate the characteristics of liposomes with different surface potentials in vitro to achieve an optimal intratumoral distribution and antitumor effect in vivo. In this study, the authors evaluated the characteristics of doxorubicin (DOX)-loaded NLPs, CLPs, polyethylene glycol (PEG)-modified NLPs (NLP-PEG), and PEGylated CLPs (CLP-PEG) (ie, encapsulation efficacy, zeta potential, size, membrane fluidity, aggregation in serum, and uptake of liposomes into rat aortic endothelial cells (RAECs)) to further understand their influences on the pharmacokinetics, biodistribution, and antitumor therapy in vivo. The results showed that increased amounts of cationic lipids resulted in severe liposome aggregation in the presence of serum, yet it did not alter the membrane fluidity to a large extent. The uptake of liposomes into RAECs, visualized by confocal fluorescence microscopy, confirmed the rapid uptake of CLP by the endothelial cells compared with NLP. However, the pharmacokinetics, biodistribution and anticancer efficacies of these liposomes in vivo revealed that the CLP with highly positive surface potentials exhibited reduced circulation times and poor distribution in tumors. The NLP-PEG exhibited the highest anticancer efficacy; CLP-PEG, the second highest; and CLP with the most positive surface potential, the lowest. These phenomena were mostly due to the rapid aggregation in serum and subsequent accumulation in the lungs upon the intravenous injection of the CLP. Caution should be exercised when chemotherapeutic drugs are loaded into CLP for tumor therapy.
Comparative study of the in vitro and in vivo characteristics of cationic and neutral liposomes
Zhao W,Zhuang S,Qi XR
International Journal of Nanomedicine , 2011,
Abstract: Wei Zhao, Song Zhuang, Xian-Rong QiDepartment of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing, People's Republic of ChinaAbstract: Neutral liposomes (NLP) exhibit preferential localization in solid tumors based on the enhanced permeation and retention (EPR) effect. Cationic liposomes (CLP) have a propensity for localizing in newly formed tumor vessels and they have a potentially enhanced antitumor effect. However, an increased amount of cationic lipids in liposomes also induces aggregation through electrostatic interactions between the liposomes and the anionic species in the circulation, which results in a reduced EPR effect. Consequently, it is important to investigate the characteristics of liposomes with different surface potentials in vitro to achieve an optimal intratumoral distribution and antitumor effect in vivo. In this study, the authors evaluated the characteristics of doxorubicin (DOX)-loaded NLPs, CLPs, polyethylene glycol (PEG)-modified NLPs (NLP-PEG), and PEGylated CLPs (CLP-PEG) (ie, encapsulation efficacy, zeta potential, size, membrane fluidity, aggregation in serum, and uptake of liposomes into rat aortic endothelial cells (RAECs)) to further understand their influences on the pharmacokinetics, biodistribution, and antitumor therapy in vivo. The results showed that increased amounts of cationic lipids resulted in severe liposome aggregation in the presence of serum, yet it did not alter the membrane fluidity to a large extent. The uptake of liposomes into RAECs, visualized by confocal fluorescence microscopy, confirmed the rapid uptake of CLP by the endothelial cells compared with NLP. However, the pharmacokinetics, biodistribution and anticancer efficacies of these liposomes in vivo revealed that the CLP with highly positive surface potentials exhibited reduced circulation times and poor distribution in tumors. The NLP-PEG exhibited the highest anticancer efficacy; CLP-PEG, the second highest; and CLP with the most positive surface potential, the lowest. These phenomena were mostly due to the rapid aggregation in serum and subsequent accumulation in the lungs upon the intravenous injection of the CLP. Caution should be exercised when chemotherapeutic drugs are loaded into CLP for tumor therapy.Keywords: cationic liposomes, PEGylation, electrostatic interaction, aggregation, anticancer efficacy, biodistribution
Digital Shearlet Transforms
G. Kutyniok,W. -Q Lim,X. Zhuang
Mathematics , 2011,
Abstract: Over the past years, various representation systems which sparsely approximate functions governed by anisotropic features such as edges in images have been proposed. We exemplarily mention the systems of contourlets, curvelets, and shearlets. Alongside the theoretical development of these systems, algorithmic realizations of the associated transforms were provided. However, one of the most common shortcomings of these frameworks is the lack of providing a unified treatment of the continuum and digital world, i.e., allowing a digital theory to be a natural digitization of the continuum theory. In fact, shearlet systems are the only systems so far which satisfy this property, yet still deliver optimally sparse approximations of cartoon-like images. In this chapter, we provide an introduction to digital shearlet theory with a particular focus on a unified treatment of the continuum and digital realm. In our survey we will present the implementations of two shearlet transforms, one based on band-limited shearlets and the other based on compactly supported shearlets. We will moreover discuss various quantitative measures, which allow an objective comparison with other directional transforms and an objective tuning of parameters. The codes for both presented transforms as well as the framework for quantifying performance are provided in the Matlab toolbox ShearLab.
An Energy Efficient MAC Protocol for Fully Connected Wireless Ad Hoc Networks
K. Rahimi Malekshan,W. Zhuang,Y. Lostanlen
Computer Science , 2014,
Abstract: Energy efficiency is an important performance measure of wireless network protocols, especially for battery-powered mobile devices such as smartphones. This paper presents a new energy-efficient medium access control (MAC) scheme for fully connected wireless ad hoc networks. The proposed scheme reduces energy consumption by putting radio interfaces in the sleep state periodically and by reducing transmission collisions, which results in high throughput and low packet transmission delay. The proposed MAC scheme can also address the energy saving in realtime traffics which require very low packet transmission delay. An analytical model is established to evaluate the performance of the proposed MAC scheme. Analytical and simulation results demonstrate that the proposed scheme has a significantly lower power consumption, achieves substantially higher throughput, and has lower packet transmission delay in comparison with existing power saving MAC protocols.
Novel Finite Difference Discretization of Interface Boundary Conditions for Stablized Explicit-Implicit Domain Decomposition Methods  [PDF]
Yu Zhuang
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26047
Abstract:

Stabilized explicit-implicit domain decomposition is a group of methods for solving time-dependent partial difference equations of the parabolic type on parallel computers. They are efficient, stable, and highly parallel, but suffer from a restriction that the interface boundaries must not intersect inside the domain. Various techniques have been proposed to handle this restriction. In this paper, we present finite difference schemes for discretizing the equation spatially, which is of high simplicity, easy to implement, attains second-order spatial accuracy, and allows interface boundaries to intersect inside the domain. 

Chemical Castration: International Experience and Chinese Path to Control Pedophilia Crimes  [PDF]
Jin Zhuang
Advances in Applied Sociology (AASoci) , 2018, DOI: 10.4236/aasoci.2018.88034
Abstract: The current penalties in China are not sufficient to effectively curb pedophilia. Chemical castration is not the corporal punishment in real sense but indicates reducing the medical treatment of the criminal’s lust by injecting anti-androgen drugs without causing perpetual harm to the criminal’s body. It includes many aspects such as penalty execution procedure & object, treatment position, and penalty execution replacement & guarantee, etc. There are characteristic regulations on it in many states of America. The drastic argument on issues including the constitutionality, fairness, effectiveness and economy of the penalty is held in the American academic circle. Chemical castration has remarkable effect in urging catamite crime, which is worth of referring to for Chinese criminal law. However, it is necessary to take precaution against the limitation in design of the specific system.
A pre-operational 3-D variational data assimilation system in the North/Baltic Sea
S. Y. Zhuang,W. W. Fu,J. She
Ocean Science Discussions (OSD) , 2011, DOI: 10.5194/osd-8-1131-2011
Abstract: This paper describes the implementation and evaluation of a pre-operational three dimensional variational (3DVAR) data assimilation system for the North/Baltic Sea. The univariate analysis for temperature and salinity is applied in a 3DVAR scheme in which the horizontal component of the background error covariance is modeled by an isotropic recursive filter (IRF) and the vertical component is represented by dominant Empirical Orthogonal Functions (EOFs) of the background error. Observations of temperature and salinity (T/S) profiles in the North/Baltic Sea are assimilated in the year of 2005. Effectiveness of the data assimilation scheme is assessed by comparison with the control run that no assimilation is done. The statistical analysis indicates that the model simulation is significantly improved with the 3DVAR scheme. On average, the root mean square error (RMSE) of temperature and salinity is reduced by 0.2 °C and 0.25 psu in the North/Baltic Sea. In addition, the bias of temperature and salinity is also decreased by 0.1 °C and 0.2 psu, respectively. Starting from an analyzed initial state, one month simulation without assimilation is carried out with the aim of examining the persistence of the initial impact. It is shown that the assimilated initial state can impact the model simulation for nearly two weeks. The influence on salinity is more pronounced than temperature.
A pre-operational three Dimensional variational data assimilation system in the North/Baltic Sea
S. Y. Zhuang,W. W. Fu,J. She
Ocean Science (OS) & Discussions (OSD) , 2011, DOI: 10.5194/os-7-771-2011
Abstract: This paper describes the implementation and evaluation of a pre-operational three dimensional variational (3DVAR) data assimilation system for the North/Baltic Sea. Univariate analysis for both temperature and salinity is applied in a 3DVAR scheme in which the horizontal component of the background error covariance is modeled by an isotropic recursive filter (IRF) and the vertical component is represented by dominant Empirical Orthogonal Functions (EOFs). Observations of temperature and salinity (T/S) profiles in the North/Baltic Sea are assimilated in the year of 2005. Effect of the 3DVAR scheme is assessed by a comparison between data assimilation run and control run. The statistical analysis indicates that the model simulation is significantly improved with the 3DVAR scheme. On average, the root mean square errors (RMSE) of temperature and salinity are reduced by 0.2 °C and 0.25 psu in the North/Baltic Sea. In addition, the bias of temperature and salinity is also decreased by 0.1 °C and 0.2 psu, respectively. Starting from an analyzed initial state, one month simulation without assimilation is carried out with the aim of examining the persistence of the initial impact. It is shown that the assimilated initial state can impact the model simulation for nearly two weeks. The influence on salinity is more pronounced than temperature.
Analysis of TACI mutations in CVID & RESPI patients who have inherited HLA B*44 or HLA*B8
Manda L Waldrep, Yingxin Zhuang, Harry W Schroeder
BMC Medical Genetics , 2009, DOI: 10.1186/1471-2350-10-100
Abstract: We identified 63 CVID patients irrespective of HLA status and 13 RESPI patients who had inherited HLA*B44. To evaluate for mutations in the gene for TACI, we PCR amplified and sequenced TACI exons 3 and 4 from these patients.Of the 76 patients, eleven proved heterozygous for a previously reported, silent T->G polymorphism [rs35062843] at proline 97 in exon 3. However, none of the 13 RESPI patients and only one of the 63 CVID patients inherited a TACI allele previously associated with CVID. This patient was heterozygous for the TACI A181E allele (exon 4). She did not carry *DQ2, *DR7, *DR3(17), *B8, or *B44.These findings suggest that TACI mutations are unlikely to play a critical role in creating susceptibility to CVID among patients with previously recognized MHC class I and class II susceptibility alleles.Supported by NIH/USIDNET N01-AI30070, NIH R21 AI079741 and NIH M01-RR00032In the United States, CVID is the most common primary immunodeficiency under the care of the clinical immunologist. CVID is a clinical diagnosis given to patients with unexplained pan-hypogammaglobulinemia in the presence of normal or near-normal B cell numbers. It has been called agammaglobulinemia with B cells to distinguish it from Bruton's agammaglobulinemia [1]. The most common clinical presentation is a history of recurrent pyogenic sinopulmonary infections [2,3]. Among Americans of European descent, it affects approximately 1 in 25,000 [4,5]. The frequency among Americans of African descent is twenty-fold lower [6]. These ethnic associations, coupled with the results of familial studies, have suggested that CVID has a strong genetic component [7,8]. However, identification of the causative genes has been difficult. It remains unclear whether the disease reflects a single Mendelian trait with incomplete penetrance, or whether it is the result of a combination of genetic lesions and environmental influences.In our clinic in the Southeastern United States, the majority of patients with
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