1,721,351 research outputs found
Bacterial Vaginosis, a Model of True Polymicrobial Infections: Genetics, Evolution, Clinical and Socio-Clinical Implications
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Bacterial Vaginosis, a Model of True Polymicrobial Infections: Genetics, Evolution, Clinical and Socio-Clinical Implications
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Vaginal colonization by Group B Streptococcus in different populations of African women : risk factors and relation with the vaginal microbiome and the cervicovaginal immune system
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Inflammatory response in maternal serum during preterm labour
Full text linkPreterm birth (PTB), defined as a delivery at less than 37 weeks of gestation, is the leading cause of perinatal morbidity and mortality worldwide. The serious effects of PTB on parents, infant and society make PTB an important issue to public health. Despite significant advances in perinatal care and advancing knowledge of risk factors and mechanisms associated with PTB, there has been little progress in reducing the PTB rate. Diagnosis of preterm labour as well as accurate prediction of PTB is notoriously difficult, because of the heterogeneity of the condition. PTB is a syndrome initiated by multiple mechanisms including infection or inflammation which is the only pathological process for which both a firm causal link with PTB has been established and a molecular pathophysiology defined. Intrauterine infection evokes an immune response that involves the release of cytokines and chemokines, prostaglandins and matrix-degrading enzymes. These substances trigger uterine contractions, membrane rupture and cervical ripening. Most intra-uterine infections are chronic and subclinical in nature and consequently hard to diagnose before labour or rupture of the membranes. A tremendous amount of efforts has been expended to identify markers to predict PTB and to improve our understanding of the mechanisms and pathways leading to PTB. The best studied site of infection is amniotic fluid, but obtaining this sample requires an invasive and sometimes risky procedure (e.g. amniocentesis). A non-invasive approach seems to be more relevant to clinical practice because of the feasibility and accessibility. However, few studies have investigated the maternal inflammatory response during preterm labour. Therefore, the overall objective of this study was to determine several inflammatory markers in maternal serum from pregnant women in labour (either term or preterm) vs. non-labouring controls.
We completed a nested case control study in which singleton pregnancies were recruited at the obstetric department of Ghent University Hospital and divided into groups according to gestational age and labour status. Multiple proteins were evaluated in maternal serum using enzyme-linked or multiplex bead immunoassays including soluble triggering receptor expressed on myeloid cells-1 (sTRE M-1), matrix metalloproteinases (MMP)-9 and MMP-3, tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, TIMP-3 and TIMP-4 and a panel of 30 cytokines, chemokines and growth factors.
Our study showed that serum levels of sTRE M-1 were elevated during spontaneous term and preterm labour vs. non-labouring women. sTRE M-1 concentrations were significantly higher in preterm vs. term labour. In line with previous studies, MMP-9 concentrations were elevated during preterm labour. TIMP-1 and TIMP-2 were lower in preterm gestation, irrespective of labour, while TIMP-4 concentrations were raised in labour. One of the most intriguing findings of our study is that MMP-9:TIMP-1 and MMP-9:TIMP-2 balances in maternal serum were tilting in favour of matrix degradation (gelatinolysis) in women with preterm labour. This observation suggests that aberrant serum expression of MMP:TIMP ratios may provide a far less invasive method to determine enzymes essential in the degradation of extracellular matrix (EC M) during pregnancy and parturition. Among the 30 inflammatory serum markers, only hepatocyte growth factor (HGF) was increased in women with PTB, while interleukin (IL)-12 serum levels were lower in labouring women and interferon gamma induced protein (IP)-10 serum levels were higher in women at term gestation. This may indicate that the inflammatory response in serum of women with term and preterm labour is rather weak. Until present, few biomarkers have shown clinical usefulness, because they are nonspecific or become positive too late. Among the biomarkers evaluated to date, the most powerful and consistent predictors of PTB are the presence of foetal fibronectin in cervicovaginal fluid and a short cervix on transvaginal ultrasound examination. The clinical value of both tests primarily lies in their negative predictive value thereby guiding clinicians in decision-making and avoiding unnecessary interventions. During the last decades, it has become clear that single or universal biomarkers will not be capable to predict PTB accurately in all populations. Future research should focus on multiple biomarkers in different PTB subtypes to allow differentiation depending on the underlying causes. The future development of an accurate, minimally invasive multiple marker test is necessary to permit incorporation into clinical practice. The availability of new technologies capable of probing the genome offers exciting possibilities to gain new insights into the mechanisms leading to PTB and to develop targeted therapies
Optimization of RNA-extraction for the study of human host : fungal pathogen interactions
No full textVulvovaginal candidiasis (VVC) is a widespread vaginal infection most frequently caused by Candida albicans which normally inhabits genitourinary tracts of healthy individuals. VVC is considered to be the second most common vaginal infection after bacterial vaginosis and its incidence is increasing significantly due to widespread increased use of antibiotics. Importantly, VVC also occurs in healthy women and can be fatal in immunocompromised individuals. The infection may additionally become recurrent (RVVC) which is defined as more than three episodes of VVC in a year, severely reducing the quality of life. Unfortunately, the causal reasons for getting multiple recurrences are not fully understood.
The number of transcriptomic studies to elucidate host pathogen interactions have increased in an attempt to unravel pathogenesis and immune control of the disease. However, although most studies have identified differently expressed genes from the host side, it is difficult to obtain sufficient RNA reads from the fungus in clinical samples, i.e., vaginal swabs, because fungal reads are underrepresented as compared to the human counterpart. In this context, RNA extraction improvements or selection of an RNA extraction method that maximizes the RNA amount obtained from fungal cells may be a first step on the path to the quantification of differently expressed genes of C. albicans. The storage medium in which clinical samples are preserved may also affect RNA extraction in terms of RNA quantity and quality, and this should maintain transcriptional profiles unmodified until RNA is extracted. In addition, cell lysis of the fungi is an essential process to guarantee high-efficient RNA extraction since the number of lysed cells impacts directly on the amount of RNA yielded.
In this thesis, we compared different cell lysis methods and different methods for RNA extraction from C. albicans stored in RNAlater, a solution that protects RNA from its degradation and avoids gene expression changes at room temperature. After detailed comparison of different approaches, we established horizontal bead beating in RiboPure Lysis Buffer followed by RNA extraction with the RiboPure Yeast Kit as the most efficient procedure to obtain the highest RNA yield. In addition, although we showed that the use of RNAlater slightly reduced RNA yield, it still offered high quality and quantity RNA that may guarantee reliable host-pathogen interactions studies. We have also compared different procedures for RNA extraction in PBMCs and we obtained similar results. Storage of human cells in RNAlater resulted in reduced RNA yield but still can be suited for high quality and quantity RNA-demanding techniques such as RNA-sequencing (RNA-seq). In addition, the RiboPure Kit also offered the highest RNA yield which makes this kit appealing for dual RNA-seq focused on the pathogen and the host. Finally, we also demonstrated that high-quality fungal nucleic acids can be enriched through the lysis of RNAlater-stored human cells by means of RLT buffer, a commercial lysis buffer used in RNeasy kits, and subsequent centrifugation to discard the nucleic acids from the human lysed cells in the supernatant. Furthermore, the enrichment of fungal nucleic acids was verified in different mixes composed of C. albicans cells and PBMCs in ratios 1:1, 1:10 and 1:100 in order to simulate realistic fungus:human proportions encountered within the host.
In summary, we have determined the best combination of RNA extraction and cell lysis method to obtain the maximum amount of RNA from fungal cells. In addition, we have established an efficient enrichment method that increases the proportion of fungal RNA without compromising gene expression. Together, these procedures provide a solution to comprehensively analyze transcriptomic profiles of C. albicans in samples biased towards human cells, such as clinical (vaginal) samples. Importantly, since the enrichment process is based on the differential lysis of human cells caused by the protective cell wall of the fungus, these procedures can be extended to other fungal pathogens. Furthermore, as the enrichment method uses centrifugation to separate human cell debris from intact fungal cells, the procedures can also be applied not only in transcriptomics but also in genomics studies
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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