bluuebunny/crossref_metadata_2025_split huggingface dataset:
Snail‐associated epithelial–mesenchymal transition promotes oesophageal squamous cell carcinoma motility and progression
Authors: Usami Y , Satake S , Nakayama F , Matsumoto M , Ohnuma K , Komori T , Semba S , Ito A , Yokozaki H 
Published: April 2008

AbstractThe essential contribution of the epithelial–mesenchymal transition (EMT) to carcinoma progression is the loss of their epithelial characters, gain of mesenchymal marker expression, acquisition of migration, invasive activity and capability to pass through the basement membrane. In this study, we aimed to clarify the role of EMT regulator Snail, a zinc finger transcription factor, in human oesophageal squamous cell carcinoma (OESCC). Most OESCC cell lines expressed epithelial cell–cell adhesion molecules such as E‐cadherin and claudin‐1 and ‐7; however, TE‐8 (Snail‐positive) cells expressed mesenchymal marker vimentin but not E‐cadherin and claudins. Transduction of ectopic Snail in TE‐15 (Snail‐negative) cells diminished expression of these epithelial adhesion molecules with promotion of cell migration, invasion and proliferation as well as the shift from cobblestone‐like appearance to spindle morphology. In OESCC tissue samples, immunohistochemical analyses revealed that the nuclear Snail expression at the invasive front was correlated with the high levels of vimentin expression (p = 0.0061), which was conversely associated with reduced expressions of E‐cadherin (p = 0.023), claudin‐1 (p = 0.0246) and claudin‐7 (p = 0.0161). Interestingly, elevated Snail expression at the invasive front of the OESCC was associated with higher incidence of lymphatic (p = 0.0143) and venous vessels invasion (p = 0.0029), lymph node metastasis (p = 0.0074) and clinicopathological tumour stage (p = 0.0057). According to the expressions of epithelial and mesenchymal markers, the tumours were subclassified into three groups, the epithelial‐type OESCC and the complete or incomplete EMT‐type OESCCs. Snail‐positive tumours were frequently categorized into the complete‐ or incomplete‐type EMT phenotypes. Our present results suggest the significance of Snail‐associated EMT in the progression of OESCC. Snail‐induced EMT at the invasive front of the OESCC can be a novel marker for the prediction of metastasis. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
New Technologies and Instruction
Authors: Clement Frank 
Published: April 2008

AbstractDigits form the language of the ubiquitous computer from the multi million dollar main frame to the digital watch. Digitization permits the storage and manipulation of such information as text, graphics, music, voice and television pictures. Digital information can be transmitted over vast distances with tremendous accuracy. In summary, the most important aspect of digitalized information is that it has opened up an information era that will put to shame anything that was done before. Understanding the digitalizing process is not necessary to its use, but it may help in understanding the vast changes that are coming to our working, learning and living environment.
Functionalization of carbon nanofibers (CNFs) through atom transfer radical polymerization for the preparation of poly(tert‐butyl acrylate)/CNF materials: Spectroscopic, thermal, morphological, and physical characterizations
Authors: Ghislandi Marcos , de A. Prado Luis Antonio Sanchez , de la Vega Oyerviedes Alejandra , Wittich Hans , Schulte Karl , Barros‐Timmons Ana 
Published: April 2008

AbstractVapor‐grown carbon nanofibers (CNFs) were oxidized and functionalized for atom transfer radical polymerization (ATRP) of tert‐butyl acrylate (t‐BA) from the surface of the CNFs. The materials were characterized by solubility tests, Fourier‐transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscopy. The FTIR and electron microscopy results suggest that ATRP process was successfully used to graft poly(tert‐butyl acrylate) (poly(t‐BA)) chains from the surface of the fibers. Raman results strongly indicate the partial degradation of the graphitic layer of CNFs because of the chemical treatments. TGA results suggest that the presence of poly(t‐BA) leads to a decrease of the initial degradation temperature of the fibers. XRD and electron microscopy results indicate that the microstructure of fibers was not destroyed because of the oxidation and functionalization processes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3326–3335, 2008
Synthesis and chiroptical properties of poly (p‐phenylenevinylene‐alt‐m‐phenylenevinylene) bearing (−)‐trans‐myrtanoxyl groups on the p‐phenylene rings
Authors: Li Xiangfeng , Li Chusheng , Yan Jiaguo , Lu Jiang , Liang Hui 
Published: April 2008

AbstractChiral poly(p‐phenylenevinylene‐alt‐m‐phenylenevinylene)s bearing (−)‐trans‐myrtanoxyl groups on the p‐phenylene rings were synthesized by Wittig's reaction and Heck's reaction, respectively, namely Myr‐PMPV‐w and Myr‐PMPV‐h correspondingly. The chiroptical properties of the polymers were investigated in chlorobenzene solution by circular dichroism. The results showed that both Myr‐PMPV‐w and Myr‐PMPV‐h showed no Cotton effect due to their irregular molecular structure. By the treatment with I2, most of the cis‐vinylene linkages in Myr‐PMPV‐w were converted to trans‐vinylenes, consequently, the structure of Myr‐PMPV‐w became much more regular, and the resulting polymer (iso‐Myr‐PMPV‐w) showed strong bisignate Cotton effects in the π–π* transition. Compared to its analogous poly(p‐phenylenevinylene) (PPV) (iso‐Myr‐PPV‐w), iso‐Myr‐PMPV‐w showed much stronger Cotton effect, its maximum g value was about one order of magnitude higher than that of iso‐Myr‐PPV‐w under the same conditions. With increasing concentration and decreasing temperature, the gmax value of iso‐Myr‐PMPV‐w increased, and the maximum absorption was slightly blue‐shifted, but the shape and range of absorption curves did not changed significantly, and no clear isosbestic point could be observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3336–3343, 2008
Frontal polymerization of diurethane diacrylates
Authors: Mariani Alberto , Fiori Stefano , Bidali Simone , Alzari Valeria , Malucelli Giulio 
Published: April 2008

AbstractThis work deals with the preparation of poly(urethane acrylates) by using two different polymerization techniques. Namely, the classical batch procedure has been compared with frontal polymerization (FP). A thorough study on the effect of initiator type, concentration, and on the velocity of the front and its maximum temperature has been carried out. Moreover, two different synthetic ways have been studied: the one step poly(urethane acrylate) preparation starting directly from 1,6 diisocyanato hexane and 2‐hydroxyethyl acrylate, and the two step procedure consisting of the synthesis of the corresponding diurethane diacrylate and of its subsequent polymerization. The first method has the advantage of being faster but some caution is necessary due to the excessive heat that is generated if the reaction conditions are not properly chosen. The second approach requires a further step but has the advantage of being more controlled. DSC analysis did not show any significant difference by comparing the thermal properties of the materials obtained by the two techniques (batch and FP). However, since FP runs are very easy and fast to be performed, FP should be seriously taken into proper account when these materials have to be prepared. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3344–3352, 2008
Influence of nitroxide structure on polystyrene brushes “grafted‐from” silicon wafers
Authors: Ostaci Roxana‐Viorela , Celle Caroline , Seytre Gérard , Beyou Emmanuel , Chapel Jean‐Paul , Drockenmuller Eric 
Published: April 2008

AbstractAlkoxyamine derivatives based on 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO), N‐tert‐butyl‐N‐(1‐diethylphosphono‐(2,2‐dimethylpropyl)) nitroxide (SG1) and N‐tert‐butyl‐N‐(2‐methyl‐1‐phenylpropyl) nitroxide (TIPNO) containing a C11 hydrophobic spacer and a reactive triethoxysilyl polar head, were synthesized and anchored to silicon wafers by the Langmuir–Blodgett reactive deposition technique at surface pressures ranging from 15 to 32 mN/m. Polystyrene brushes (Mn ∼ 8500–66,400 g/mol) were grown from the alkoxyamine functionalized silicon wafers by nitroxide mediated radical polymerization and characterized by ellipsometry and water contact angle measurements. The main parameters influencing the grafting density and the degree of stretching of the brushes are the nitroxide polarity and, therefore, the behavior of the corresponding alkoxyamines at the air/water interface of the Langmuir–Blodgett trough. Depending on the alkoxyamine chemical structure and the surface pressure during Langmuir–Blodgett deposition, polystyrene brushes with grafting densities of 0.3–1.0 chains/nm2 and stretching values of 40–70% were obtained. Regarding alkoxyamines deposited at high surface pressures, size exclusion chromatography experiments performed on both cleaved polystyrene brushes and chains simultaneously grown in the bulk revealed that the polymerization degree of the bulk and surface chains are significantly different, suggesting that steric constrains affect the polymerization kinetics occurring at the silicon surface. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3367–3374, 2008
A new photoiniferter/RAFT agent for ambient temperature rapid and well‐controlled radical polymerization
Authors: Tasdelen Mehmet Atilla , Durmaz Yasemin Yuksel , Karagoz Bunyamin , Bicak Niyazi , Yagci Yusuf 
Published: April 2008

AbstractPhenacyl morpholine‐4‐dithiocarbamate is synthesized and characterized. Its capability to act as both a photoiniferter and reversible addition fragmentation chain transfer agent for the polymerization of styrene is examined. Polymerization carried out in bulk under ultra violet irradiation at above 300 nm at room temperature shows controlled free radical polymerization characteristics up to 50% conversions and produces well‐defined polymers with molecular weights close to those predicted from theory and relatively narrow poyldispersities (Mw/Mn ∼ 1.30). End group determination and block copolymerization with methyl acrylate suggest that morpholino dithiocarbamate groups were attained at the end of the polymer. Photolysis and polymerization studies revealed that polymerization proceeds via both reversible termination and RAFT mechanisms. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3387–3395, 2008
Transition metal complexes of a cyclic pseudo hexapeptide: synthesis, complex formation and catalytic activities
Authors: Ngyen Huong , Orlamuender Marit , Pretzel David , Agricola Inge , Sternberg Ulrich , Reissmann Siegmund 
Published: April 2008

AbstractTo contribute to a better understanding of metalloenzymes, we studied ion selectivity, complex formation tendencies and catalytic activities of linear and cyclic pseudopeptides. In this contribution, a linear and cyclic pseudo hexapeptide is described. The complex with transition metal ions and the sequence were designed using the programme COSMOS. Different routes of solid‐phase synthesis were performed and compared using anchoring by C‐terminus or a His side chain, using preformed pseudodipeptide building units or formation of N‐functionalized peptide bond during stepwise assembly. The different strategies were compared regarding cyclization tendency, yield and purity. Side‐chain anchoring to solid support favours the cyclization but leads to the formation of difficult to separate dioxopiperazine. Both routes require preformed building units. Complex‐formation tendencies and selectivity for certain bivalent transition metal ions were experimentally estimated and compared to ones predicted theoretically. CD measurements indicate conformational changes by complex formation with different metal ions. Catalytic activities on oxidation of catechol and hydrolysis of bis‐phosphate esters by some metal complexes of linear and cyclic peptide show only low catalytic activities compared to other model peptides and related metalloenzymes. The preference of the cyclic peptide for complexation of Ni2+ corresponds well to the predictions of COSMOS‐NMR force field calculations. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
First‐principles study on electronic structure of fullerene polymers
Authors: Kitajima H. , Egami Y. , Nakayama H. , Hirose K. , Ono T. 
Published: April 2008

AbstractThe geometrical structures and electronic properties of P66 fullerene‐polymer sheets areinvestigated using semiempirical tight‐binding calculations and first‐principles calculationsbased on the density functional theory. Our results indicate that the sheet becomes metallic when the [2 + 2] cycloadditional bond between the two neighboring P66 polymer chains is stretched. We also examine the electronic structure of the sheet sandwiched between electrodes and found that the sheet exhibits metallic behavior. Copyright © 2008 John Wiley & Sons, Ltd.
Parametric robust inferences for correlated ordinal data
Authors: Tsou Tsung‐Shan , Shen Chung‐Wei 
Published: April 2008

AbstractThe aim of this article is to provide asymptotically valid likelihood inferences about regression parameters for correlated ordinal response variables. The legitimacy of this novel approach requires no knowledge of the underlying joint distributions so long as their second moments exist. The efficacy of the proposed parametric approach is demonstrated via simulations and the analyses of two real data sets. Copyright © 2008 John Wiley & Sons, Ltd.
Analyzing sequentially randomized trials based on causal effect models for realistic individualized treatment rules
Authors: Bembom Oliver , van der Laan Mark J. 
Published: April 2008

AbstractIn this paper, we argue that causal effect models for realistic individualized treatment rules represent an attractive tool for analyzing sequentially randomized trials. Unlike a number of methods proposed previously, this approach does not rely on the assumption that intermediate outcomes are discrete or that models for the distributions of these intermediate outcomes given the observed past are correctly specified. In addition, it generalizes the methodology for performing pairwise comparisons between individualized treatment rules by allowing the user to posit a marginal structural model for all candidate treatment rules simultaneously. This is particularly useful if the number of such rules is large, in which case an approach based on individual pairwise comparisons would be likely to suffer from too much sampling variability to provide an informative answer. In addition, such causal effect models represent an interesting alternative to methods previously proposed for selecting an optimal individualized treatment rule in that they immediately give the user a sense of how the optimal outcome is estimated to change in the neighborhood of the identified optimum. We discuss an inverse‐probability‐of‐treatment‐weighted (IPTW) estimator for these causal effect models, which is straightforward to implement using standard statistical software, and develop an approach for constructing valid asymptotic confidence intervals based on the influence curve of this estimator. The methodology is illustrated in two simulation studies that are intended to mimic an HIV/AIDS trial. Copyright © 2008 John Wiley & Sons, Ltd.
Identifying significant covariates for anti‐HIV treatment response: Mechanism‐based differential equation models and empirical semiparametric regression models
Authors: Huang Yangxin , Liang Hua , Wu Hulin 
Published: April 2008

AbstractIn this paper, the mechanism‐based ordinary differential equation (ODE) model and the flexible semiparametric regression model are employed to identify the significant covariates for antiretroviral response in AIDS clinical trials. We consider the treatment effect as a function of three factors (or covariates) including pharmacokinetics, drug adherence and susceptibility. Both clinical and simulated data examples are given to illustrate these two different kinds of modeling approaches. We found that the ODE model is more powerful to model the mechanism‐based nonlinear relationship between treatment effects and virological response biomarkers. The ODE model is also better in identifying the significant factors for virological response, although it is slightly liberal and there is a trend to include more factors (or covariates) in the model. The semiparametric mixed‐effects regression model is very flexible to fit the virological response data, but it is too liberal to identify correct factors for the virological response; sometimes it may miss the correct factors. The ODE model is also biologically justifiable and good for predictions and simulations for various biological scenarios. The limitations of the ODE models include the high cost of computation and the requirement of biological assumptions that sometimes may not be easy to validate. The methodologies reviewed in this paper are also generally applicable to studies of other viruses such as hepatitis B virus or hepatitis C virus. Copyright © 2008 John Wiley & Sons, Ltd.
A distribution‐free test of constant mean in linear mixed effects models
Authors: Lim Johan , Wang Xinlei , Lee Seokho , Jung Sin‐Ho 
Published: April 2008

AbstractWe propose a distribution‐free procedure, an analogy of the DIP test in non‐parametric regression, to test whether the means of responses are constant over time in repeated measures data. Unlike the existing tests, the proposed procedure requires very minimal assumptions to the distributions of both random effects and errors. We study the asymptotic reference distribution of the test statistic analytically and propose a permutation procedure to approximate the finite‐sample reference distribution. The size and power of the proposed test are illustrated and compared with competitors through several simulation studies. We find that it performs well for data of small sizes, regardless of model specification. Finally, we apply our test to a data example to compare the effect of fatigue in two different methods used for cardiopulmonary resuscitation. Copyright © 2008 John Wiley & Sons, Ltd.
Modeling heaping in self‐reported cigarette counts
Authors: Wang Hao , Heitjan Daniel F. 
Published: April 2008

AbstractIn studies of smoking behavior, some subjects report exact cigarette counts, whereas others report rounded‐off counts, particularly multiples of 20, 10 or 5. This form of data reporting error, known as heaping, can bias the estimation of parameters of interest such as mean cigarette consumption. We present a model to describe heaped count data from a randomized trial of bupropion treatment for smoking cessation. The model posits that the reported cigarette count is a deterministic function of an underlying precise cigarette count variable and a heaping behavior variable, both of which are at best partially observed. To account for an excess of zeros, as would likely occur in a smoking cessation study where some subjects successfully quit, we model the underlying count variable with zero‐inflated count distributions. We study the sensitivity of the inference on smoking cessation by fitting various models that either do or do not account for heaping and zero inflation, comparing the models by means of Bayes factors. Our results suggest that sufficiently rich models for both the underlying distribution and the heaping behavior are indispensable to obtaining a good fit with heaped smoking data. The analyses moreover reveal that bupropion has a significant effect on the fraction abstinent, but not on mean cigarette consumption among the non‐abstinent. Copyright © 2008 John Wiley & Sons, Ltd.
An index approach for the Cox model with left censored covariates
Authors: D'Angelo Gina , Weissfeld Lisa ,   on behalf of the GenIMS Investigators
Published: April 2008

AbstractMedical studies frequently collect biological markers in which many subjects have values below the detectable limits of the assay, resulting in heavily censored data. We develop a modification of the Rigobon and Stoker index method for application to a Cox regression model with censored covariates. The index approach is compared with a complete case method and various fill‐in methods. Our simulation results demonstrated that the index approach is an improvement over the other methods. We illustrated the usefulness of this approach with an example for the GenIMS study examining the relationship between two inflammatory markers and survival. Copyright © 2008 John Wiley & Sons, Ltd.
Interval estimation of risk difference for data sampled from clusters
Authors: Paul Sudhir R. , Zaihra Tasneem 
Published: April 2008

AbstractRisk difference (RD) is an important measure in epidemiological studies where the probability of developing a disease for individuals in an exposed group, for example, is compared with that in a control group. There are varying cluster sizes in each group and the binary responses within each cluster cannot be assumed independent. Under the cluster sampling scenario, Lui (Statistical Estimation of Epidemiological Risk. Wiley: CA, 2004; 7–27) discusses four methods for the construction of a confidence interval for the RD. In this paper we introduce two very simple methods. One method is based on an estimator of the variance of a ratio estimator (Sampling Techniques (3rd edn). Wiley: New York, 1977; 30–67) and the other method is based on a sandwich estimator of the variance of the regression estimator using the generalized estimating equations approach of Zeger and Liang (Biometrics 1986; 42:121–130). These two methods are then compared, by simulation, in terms of maintaining nominal coverage probability and average coverage length, with the four methods discussed by Lui (Statistical Estimation of Epidemiological Risk. Wiley: CA, 2004; 7–27). Simulations show at least as good properties of these two methods as those of the others. The method based on an estimate of the variance of a ratio estimator performs best overall. It involves a very simple variance expression and can be implemented with a very few computer codes. Therefore, it can be considered as an easily implementable alternative. Copyright © 2008 John Wiley & Sons, Ltd.
Confidence intervals for P(Y1>Y2) with normal outcomes in linear models
Authors: Tian Lili 
Published: April 2008

AbstractRecently, there is an emerging interest in the inference of P(Y1>Y2) where Y1 and Y2 stand for two independent continuous random variables. So far, most of the research in this field focuses on simply comparing two outcomes without adjusting for covariates. This paper mainly presents a large sample approach based on a noncentral t distribution for the confidence interval estimation of P(Y1>Y2) with normal outcomes in linear models. Furthermore, the performance of the proposed large sample approach is compared with that of a generalized variable approach and a bootstrap approach. Simulation studies demonstrate that for small‐to‐medium sample sizes, both the large sample approach and the generalized variable approach provide confidence intervals with satisfying coverage probabilities whereas the bootstrap approach can be slightly liberal for certain scenarios. The proposed approaches are applied to three real‐life data sets. Copyright © 2008 John Wiley & Sons, Ltd.