1,721,016 research outputs found
Biosampling and biobanking (Chapter7)
No full textThis handbook is the first of its kind to address the unique needs and opportunities in sub-Saharan Africa for cancer researchers. By covering the topics fundamental to all cancer research, but from an African perspective, the handbook serves as a tool for investigators at all levels and from many backgrounds to raise the level of cancer research being undertaken in Africa. It is meant to serve as a guide for those who want to develop or expand careers in research in Africa. This handbook may also be of use to those who are in a position to foster research in Africa, including non-African scientists, governmental and nongovernmental agencies and advocacy groups
Parkinson: Biobanking applied to cells and biomarkers
No full textBiomedical research aims to understand the pathological and pathophysiological mechanisms that cause disease. Neurodegenerative diseases, such as Parkinson’s disease (PD), are major contributors to the burden of disease across the globe. PD is an age-related, progressive neurodegenerative disease. The pathological hallmarks are a selective loss of dopaminergic neurons from the substantia nigra in conjunction with the presence of protein aggregates involving α-synuclein in the residual neurons. Cystatin C expression has been shown to become upregulated in brain injuries, neurological disorders and in animal models of neurodegenerative states, which suggests it could play a part in neurodegenerative disorders. The main function of this primarily secreted protein is the inhibition of cysteine proteases.
Various tools are available to researchers to study diseases, ranging from animal models, human biospecimens and human in vitro models. Regardless of the model selected, reproducibility is crucial to ensure meaningful research. To maximise the quality of biomedical research, biobanks work to ensure the biospecimens they issue are compromised as little as possible as a consequence of the unavoidable preanalytical variables occurring during their collection, processing and storage. The scientific discipline that studies preanalytical variables and how they affect biospecimens is called biospecimen science. In this thesis, biospecimen science was applied to patient specific stem cells and cystatin C in the scope of PD research. A standardized research-grade human induced pluripotent stem cell (iPSC) workflow was established for use as an in vitro PD model, which encompasses both iPSC generation and cryostorage. Controlled-rate freezing of iPSCs using three different dimethyl sulfoxide-based cryosolutions containing ice recrystallization inhibitors was evaluated and optimized to achieve efficient iPSC cryopreservation. A double, indirect sandwich ELISA was established to quantify the concentration and the degradative state of secreted cystatin C. The ELISA was validated using well-defined and standardized cerebrospinal fluid (CSF) biospecimens, then applied as a tool to retrospectively identify CSF biospecimens that had been stored in suboptimal conditions. Secreted cystatin C was quantified and compared in blood derivatives (plasma and serum) and in the culture media of derived models (iPSCs, neuroepithelial stem cells and midbrain organoids) from three idiopathic PD patients and age-matched healthy controls. The standardized in vitro PD models, novel quality control and cryopreservation methods not only demonstrate the critical importance of preanalytical standardization but open the way to future biomedical research
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Development of biospecimen quality control tools and disease diagnostic markers by metabolic profiling
No full textIn metabolomics-based biomarker studies, the monitoring of pre-analytical variations is
crucial and requires quality control tools to enable proper sample quality evaluation. In
this dissertation work, biospecimen research and machine learning algorithms are applied
(1) to develop sample quality assessment tools and (2) to develop disease-specific diagnostic
models.
In this regard, a novel plasma sample quality assessment tool, the LacaScore, is presented.
The LacaScore plasma quality assessment is based on the plasma levels of ascorbic acid
and lactic acid. The biggest challenge in metabolomics analyses is that the sample quality
is often not known. The presented tool enhances the knowledge and importance of the
monitoring of pre-analytical variations, such as pre-centrifugation time and temperature,
prior to sample analysis in the emerging field of metabolomics. Based on the LacaScore,
decisions on the suitability/fit-for-purpose of a given sample or sample cohort can be
made.
In this dissertation work, the knowledge on sample quality was applied in a biomarker
discovery study based on cerebrospinal fluid (CSF) from early-stage Parkinson’s disease
(PD) patients. To date, no markers for the diagnosis of Parkinson’s disease are available.
In this work, a non-targeted GC-MS approach is presented and shows significant changes
in the metabolic profile in CSF from early-stage PD patients compared to matched healthy
control subjects. Based on these findings, a biomarker signature for the prediction of earlystage
PD has been developed by the application of sophisticated machine learning algorithms.
This disease-specific signature is composed of metabolites involved in inflammation,
glycosylation/glycation and oxidative stress response.
In summary, this dissertation illustrates the importance of sample quality monitoring
in biomarker studies that are often limited by small amounts of human body fluids. The
monitoring of sample quality enhances the robustness and reproducibility of biomarker
discovery studies. In addition, proper data analysis and powerful machine learning algorithms
enable the generation of potential disease diagnosis biomarker signatures
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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