1,720,986 research outputs found
PIK3CA mutation in gastric cancer and the role of microsatellite instability status in mutations of exons 9 and 20 of the PIK3CA gene
Get PDFBackground. A better understanding of molecular gastric cancer (GC) entities may help in tailored treatments of that neoplasm. The PIK3CA mutation is one of the most important in many cancers. Objectives. We performed a comparison of clinical and pathological data of the PIK3CA mutation in GC patients. Material and methods. The analysis was done on 472 patients operated on in one center. Polymerase chain reaction (PCR) was used for the screening of PIK3CA (exon 9 and 20). For microsatellite instability (MSI) we used 5 quasi-monomorphic mononucleotide repeats − BAT-26, BAT-25, NR-24, NR-21, and NR-27. The clinical and pathological data was analyzed. Results. PIK3CA mutation was observed in 10 out of 472 GC patients (2.1%). Nine out of 10 were MSI (9 of 111 MSI patients – 8.1%). Half of the 10 patients had mutations in exon 9 and the other half in exon 20. A majority of patients with the PIK3CA mutation had MSI (p < 0.001). The 5-year survival of MSI patients with the PIK3CA mutation was 40% and without the mutation, 70.4% (p = 0.309). For patients with the mutation in exon 9, the 5-year survival was 0%, and for those with the mutation in exon 20, 80% (p = 0.031). The Cox proportional hazards regression analysis did not show that PIK3CA is statistically correlated with a worse overall survival. Conclusions. PIK3CA mutation in GC is a rare finding. It is strongly associated with the MSI molecular subgroup, presenting a worse outcome than other MSI patients. A completely different outcome is associated with the mutation in exon 9 compared to the mutation in exon 20, with the latter being more favorable
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
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
Histological variety of gastric carcinoma and Helicobacter pylori cagA and vacA polymorphism
No full textBACKGROUND:
Helicobacter pylori infection may increase the risk of both histotypes of gastric carcinoma (GC): intestinal (IGC) and diffuse (DGC). Polymorphism of the main H. pylori virulence factors, cagA and vacA, could have a different impact on the histological variety of GC.
METHODS:
Two hundred and twenty-six H. pylori colonies were examined from 28 GC patients: 15 with IGC and 13 with DGC. DNA was extracted from bacteria and a PCR was performed using primers specific for cagA, the 3' cagA variable region and s and m regions of vacA.
RESULTS:
There were 214 cagA+ strains and 55.61% of them were isolated from IGC cases; there were 12 cagA- colonies and they were all isolated from DGC (P<0.001). Most patients were infected by strains with more than one cagA structural type. No strains with a particular cagA type were found to be significantly more frequent in either histological variety of GC. A percentage of 43.90 of strains with vacA subtype s1/m1 were isolated from IGC, whereas 80.95% of vacA subtype s1/m2 strains were isolated from DGC cases (P<0.001).
CONCLUSION:
Polymorphism of the main virulence genes of H. pylori may play different roles in the pathogenesis of IGC and DGC
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
A Look Into the Evolution of Epstein-Barr Virus-Induced Lymphoproliferative Disorders: A Case Study
No full textObjectives: Epstein-Barr virus (EBV) induced lymphoproliferative disorders (LPDs) are lymphoid proliferations arising as a result of the loss of an effective EBV-specific cytotoxic T-cell response. LPDs may occur for primary or acquired impairment of the immune system, as well as in some persons without documented immunodeficiency.
Methods: In this article, we describe the case of a human immunodeficiency virus positive patient affected by an EBV-LPD of the stomach who developed a nodal diffuse large B-cell lymphoma with complex morphologic and molecular features.
Results: GeneScan analysis of the gastric specimen identified two different heavy-chain immunoglobulin gene (IGH) rearrangements characterized by a dominant peak of 285 base pairs (bp) in length and a smaller peak of 266 bp in length. In the lymph node sample, IGH evaluation also demonstrated two different peaks; however, the main peak corresponded to the minor peak detected in the EBV-LPD specimen at the diagnosis. In addition, a monoclonal immunoglobulin light chain gene (IGL) rearrangement was also found We also demonstrated that the major peak in the stomach corresponded to the EBV-positive population observed in the histologic sections.
Conclusions: This case may provide additional insights to better understanding the "hit-and-run" role for EBV in lymphomagenesis. However, we could not exclude that our findings represent the co-occurrence of two unrelated B-cell neoplasms rather than a progression from an EBV-positive neoplasm to an EBV-negative one
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