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OALib Journal期刊

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Palestra de despedida: 100o Semestre de Ciência da Religi o
Peter Antes
REVER : Revista de Estudos da Religi?o , 2012,
Abstract:
Registering clinical trials is necessary for ethical, scientific and economic reasons
Antes Gerd
Bulletin of the World Health Organization , 2004,
Abstract:
Predicting MHC class I epitopes in large datasets
Kirsten Roomp, Iris Antes, Thomas Lengauer
BMC Bioinformatics , 2010, DOI: 10.1186/1471-2105-11-90
Abstract: We have examined the performance of four diverse MHC Class I prediction methods on comparatively large HLA-A and HLA-B allele peptide binding datasets extracted from the Immune Epitope Database and Analysis resource (IEDB). The chosen methods span a representative cross-section of available methodology for MHC binding predictions. Until the development of IEDB, such an analysis was not possible, as the available peptide sequence datasets were small and spread out over many separate efforts. We tested three datasets which differ in the IC50 cutoff criteria used to select the binders and non-binders. The best performance was achieved when predictions were performed on the dataset consisting only of strong binders (IC50 less than 10 nM) and clear non-binders (IC50 greater than 10,000 nM). In addition, robustness of the predictions was only achieved for alleles that were represented with a sufficiently large (greater than 200), balanced set of binders and non-binders.All four methods show good to excellent performance on the comprehensive datasets, with the artificial neural networks based method outperforming the other methods. However, all methods show pronounced difficulties in correctly categorizing intermediate binders.A precise understanding of host immune responses is crucial for basic immunological studies as well as for designing effective disease prevention strategies. Epitope-based analysis methods are effective approaches at assessing immune response, allowing for the quantification of the interaction between a host and pathogen, of vaccine effectiveness or other prevention strategies.As part of the adaptive immune response, antigens are recognized by two different types of receptor molecules: immunoglobulins which act as antigen receptors on B cells and antigen-specific T-cell receptors (TCRs) [1,2]. The latter receptor molecules recognize antigens which are displayed on the surface of cells. These antigens are peptide fragments derived from intracellular p
The demise of the randomised controlled trial: bibliometric study of the German-language health care literature, 1948 to 2004
Daniel Galandi, Guido Schwarzer, Gerd Antes
BMC Medical Research Methodology , 2006, DOI: 10.1186/1471-2288-6-30
Abstract: Eight German language general health care journals were searched for randomised controlled trials and analysed with respect to the number of published RCTs each year and the size of trials.A total of 1618 trials were identified with a median total number of 43 patients per trial. Between 1970 and 2004 a small but constant rise in sample size from a median number of 30 to 60 patients per trial can be observed. The number of published trials was very low between 1948 and 1970, but increased between 1970 and 1986 to a maximum of 11.2 RCTs per journal and year. In the following time period a striking decline of the number of RCTs was observed. Between 1999 and 2001 only 0.8 RCTs per journal and year were published, in the next three years, the number of published trials increased to 1.7 RCTs per journal and year.German language general health care journals no longer have a role in the dissemination of trial results. The slight rise in the number of published RCTs in the last three years can be explained by a change of publication language from German to English of three of the analysed journals.Approximately more than 10,000 randomised controlled trials (RCTs) – widely acknowledged as the gold standard for the evaluation of medical interventions – are published each year. Systematic reviews of RCTs, such as those disseminated through the Cochrane Collaboration, synthesise the results of individual trials to facilitate the use of external evidence in clinical decision making. The process of systematic reviewing is designed to maximise validity. This is accomplished with a series of steps to minimise bias, such as a comprehensive literature search. Indeed, the exhaustive identification of trials, irrespective of the language of publication, seems important to reduce systematic errors like language bias. Studies investigating the influence of language bias reveal controversial findings. For the comparison of German and English-language trials, a significant trend towards p
Quantitative Analysis of the Association Angle between T-cell Receptor Vα/Vβ Domains Reveals Important Features for Epitope Recognition
Thomas Hoffmann?,Angela M. Krackhardt?,Iris Antes
PLOS Computational Biology , 2015, DOI: 10.1371/journal.pcbi.1004244
Abstract: T-cell receptors (TCR) play an important role in the adaptive immune system as they recognize pathogen- or cancer-based epitopes and thus initiate the cell-mediated immune response. Therefore there exists a growing interest in the optimization of TCRs for medical purposes like adoptive T-cell therapy. However, the molecular mechanisms behind T-cell signaling are still predominantly unknown. For small sets of TCRs it was observed that the angle between their Vα- and Vβ-domains, which bind the epitope, can vary and might be important for epitope recognition. Here we present a comprehensive, quantitative study of the variation in the Vα/Vβ interdomain-angle and its influence on epitope recognition, performing a systematic bioinformatics analysis based on a representative set of experimental TCR structures. For this purpose we developed a new, cuboid-based superpositioning method, which allows a unique, quantitative analysis of the Vα/Vβ-angles. Angle-based clustering led to six significantly different clusters. Analysis of these clusters revealed the unexpected result that the angle is predominantly influenced by the TCR-clonotype, whereas the bound epitope has only a minor influence. Furthermore we could identify a previously unknown center of rotation (CoR), which is shared by all TCRs. All TCR geometries can be obtained by rotation around this center, rendering it a new, common TCR feature with the potential of improving the accuracy of TCR structure prediction considerably. The importance of Vα/Vβ rotation for signaling was confirmed as we observed larger variances in the Vα/Vβ-angles in unbound TCRs compared to epitope-bound TCRs. Our results strongly support a two-step mechanism for TCR-epitope: First, preformation of a flexible TCR geometry in the unbound state and second, locking of the Vα/Vβ-angle in a TCR-type specific geometry upon epitope-MHC association, the latter being driven by rotation around the unique center of rotation.
Distribution of Country of Origin in Studies Used in Cochrane Reviews
Robert F. Wolff,Stefan Reinders,Michael Barth,Gerd Antes
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018798
Abstract: Inclusion in systematic reviews is one important component in judging the potential impact of clinical studies upon practice and hence the ‘value for money’ of spending for clinical research. This study aims to quantify the distribution of countries of origin of clinical studies used in Cochrane Reviews (CRs), and to link these data to the size of a country and to its spending on research.
Scientific Value of Systematic Reviews: Survey of Editors of Core Clinical Journals
Joerg J. Meerpohl, Florian Herrle, Gerd Antes, Erik von Elm
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035732
Abstract: Background Synthesizing research evidence using systematic and rigorous methods has become a key feature of evidence-based medicine and knowledge translation. Systematic reviews (SRs) may or may not include a meta-analysis depending on the suitability of available data. They are often being criticised as ‘secondary research’ and denied the status of original research. Scientific journals play an important role in the publication process. How they appraise a given type of research influences the status of that research in the scientific community. We investigated the attitudes of editors of core clinical journals towards SRs and their value for publication. Methods We identified the 118 journals labelled as “core clinical journals” by the National Library of Medicine, USA in April 2009. The journals’ editors were surveyed by email in 2009 and asked whether they considered SRs as original research projects; whether they published SRs; and for which section of the journal they would consider a SR manuscript. Results The editors of 65 journals (55%) responded. Most respondents considered SRs to be original research (71%) and almost all journals (93%) published SRs. Several editors regarded the use of Cochrane methodology or a meta-analysis as quality criteria; for some respondents these criteria were premises for the consideration of SRs as original research. Journals placed SRs in various sections such as “Review” or “Feature article”. Characterization of non-responding journals showed that about two thirds do publish systematic reviews. Discussion Currently, the editors of most core clinical journals consider SRs original research. Our findings are limited by a non-responder rate of 45%. Individual comments suggest that this is a grey area and attitudes differ widely. A debate about the definition of ‘original research’ in the context of SRs is warranted.
Transient wave propagation phenomena at visco-elastic half-spaces under distributed surface loadings
Mesquita, E;Antes, H;Thomazo, LH;Adolph, M;
Latin American Journal of Solids and Structures , 2012, DOI: 10.1590/S1679-78252012000400003
Abstract: this article analyzes the transient wave propagation phenomena that take place at 2d viscoelastic half-spaces subjected to spatially distributed surface loadings and to distinct temporal excitations. it starts with a fairly detailed review of the existing strategies to describe transient analysis for elastic and viscoelastic continua by means of the boundary element method (bem). the review explores the possibilities and limitations of the existing transient bem procedures to describe dynamic analysis of unbounded viscoelastic domains. it proceeds to explain the strategy used by the authors of this article to synthesize numerically fundamental solutions or auxiliary states that allow an accurate analysis of transient wave propagation phenomena at the surface of viscoelastic half-spaces. in particular, segments with spatially constant and linear stress distributions over a halfspace surface are considered. the solution for the superposition of constant and discontinuous adjacent elements as well as linear and continuous stress distributions is addressed. the in uence of the temporal excitation type and duration on the transient response is investigated. the present study is based on the numerical solution of stress boundary value problems of (visco)elastodynamics. in a first stage, the solution is obtained in the frequency domain. a numerical integration strategy allows the stationary solutions to be determined for very high frequencies. the transient solutions are obtained, in a second stage, by applying the fast fourier transform (fft) algorithm to the previously synthesized frequency domain solutions. viscoelastic effects are taken into account by means of the elastic-viscoelastic correspondence principle. by analyzing the transient solution of the stress boundary value problems, it is possible to show that from every surface stress discontinuity three wave fronts are generated. the displacement velocity of these wave fronts can be associated to compression, shear
A imagem pública dos primeiros tempos do Isl é freqüentemente a de uma religi o que se espalhava 'a ferro e fogo...'
Entrevista de Frank Usarski com Prof. Dr. Dr. Peter Antes
REVER : Revista de Estudos da Religi?o , 2001,
Abstract:
Quedas e fraturas entre residentes de institui es de longa permanência para idosos Falls and fractures among older adults living in long-term care
Giovani Firpo Del Duca,Danielle Ledur Antes,Pedro Curi Hallal
Revista Brasileira de Epidemiologia , 2013,
Abstract: OBJETIVO: Investigar a ocorrência de quedas e fraturas no último ano e fatores associados entre residentes de institui es de longa permanência para idosos (ILPI). MéTODOS: Estudo transversal exploratório, a partir de um censo realizado em ILPI localizadas em Pelotas, Rio Grande do Sul, em 2008. As quedas e fraturas decorrentes dessas foram investigadas a partir de autorrelato referente ao último ano. Sexo, idade, escolaridade, incapacidade funcional para atividades básicas da vida diária, tipo de financiamento da institui o e hospitaliza o no último ano foram coletados como potencias fatores associados à ocorrência de queda no último ano. Empregou-se o teste qui-quadrado para heterogeneidade e tendência linear e, na análise ajustada, a regress o de Poisson com variancia robusta. RESULTADOS: Nas 24 ILPI incluídas no estudo, coletaram-se dados de 466 indivíduos. A prevalência de quedas no último ano foi de 38,9% (IC95%: 34,5 - 43,4). Dentre aqueles que caíram, as fraturas acometeram 19,2%. As fraturas mais frequentes foram: fêmur/quadril (43,3%) e punho (10%). Na análise ajustada, o avan o da idade, apresentar incapacidade funcional em uma a cinco atividades da vida diária, residir em institui es públicas/filantrópicas e ter sido hospitalizado no último ano associaram-se à queda no último ano. CONCLUS O: A alta ocorrência de quedas e fraturas entre residentes de institui es de longa permanência para idosos revela a fragilidade da popula o avaliada. Aten o específica deve ser destinada a indivíduos mais velhos e hospitalizados no último ano. OBJECTIVE: To investigate the prevalence of falls and fractures over the past 12 months and associated factors among older adults living in long-term care. METHODS: Census of all long-term care located in the city of Pelotas, Brazil, in 2008. Falls over the past 12 months were assessed using the following question: "Over the last 12 months, have you fallen?" For those who replied positively, another question was asked: "In any of these falls, have you fractured a bone?" Sex, age, schooling, disability relating to basic activities of daily living, type of financing of the long-term care and hospital admissions were the independent variables. We used chi-square tests for heterogeneity and linear trend in the unadjusted analysis, and Poisson regression with robust variance in the adjusted one. RESULTS: Within the 24 long-term care studied, we collected data for 466 individuals. The prevalence of falls in the past year was 38.9% (95%CI 34.5; 43.4). Among those who have fallen, 19.2% had fractures. Femur (hip) was th
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