1,721,003 research outputs found
12-YEAR-OLD BOY WITH MULTIPLE BRAIN MASSES
No full textThe occurrence of more than one brain tumor in a single patient is not new, resulting from RT- or CT-induced neoplasms, syndromes or casual association. We report on the exceptional case of a 12-year-old boy harboring three different brain tumors with no definite correlation. The first MRI showed a medulloblastoma with signs of infratentorial and supratentorial tumor spreading, including a small frontal mass. Despite the good response to surgical and adjuvant treatment, the frontal mass remained unchanged and was excised, revealing a lipoastrocytoma. Finally, the possible local recurrence of the original medulloblastoma was a pilocytic astrocytoma with post-radiation alterations. Explanations of this very unusual association include radio-induced tumors, second tumors developing from remnants of medulloblastoma cancer stem cells, or the changing histology after adjuvant therapy
Tibial nerve tumor in a 72-year-old man
No full textWe read with great interest the recent articles of Buttarelli et al. [1] and Srivastava et al. [2] on MGMT status in pediatric high-grade gliomas. The authors observed MGMT promoter methylation in 7/24 (30%) and 10/20 (50%) of the tumors, respectively.
In adults, MGMT promoter methylation is the most promising prognostic marker to predict patients' outcome and it has been observed in the 30–40% of the cases. On the other hand, only sporadic information are available regarding pediatric cases.
In their seminal work, Donson and colleagues [3] observed four of ten (40%) GBM pediatric patients with methylation of the MGMT gene promoter and that the methylated cases were associated with an improved survival time. Moreover, MGMT down-regulation was associated with a good response to temozolomide therapy. Recently, Schlosser and colleagues demonstrated promoter methylation in 77% of pediatric high-grade gliomas [4].
To further investigate the role of MGMT promoter methylation status in this specific group of tumors, we retrospectively surveyed a series of ten pediatric patients surgically treated from January 2001 to September 2008, at the Department of Pediatrics (Pediatric Neurosurgery Unit) of the University Hospital of Padova (seven grade IV and three grade III gliomas). Patients included five males and five females with a mean age of 12.3 years (median 11.5 years) at diagnosis. In five cases, the surgical excision of the tumor mass was partial, in two cases sub-total and in three cases complete. All patients received post-operative chemotherapy with temozolomide (in seven cases combined with other alkylating agents) and radiation therapy. Overall, all patients suffered relapse or progression of the disease: three patients are still alive, whereas seven died. MGMT status assessment was performed as previously described [5], and no case of MGMT promoter methylation has been detected.
This divergent data underlines the fact that we are still far from a well-defined characterization of pediatric cases. Further larger and multi-Institutional studies should investigate and validate the significant role of MGMT promoter methylation status assessment as a potential prognostic factor in pediatric high-grade gliomas, as well as to design different trials and treatment strategies for patients with unmethylated MGMT promoter
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
Embryonal tumors with abundant neuropil and true Rosettes: A distinctive CNS primitive neuroectodermal tumor
Full text linkEmbryonal neoplasms of the central nervous system (CNS) generally arise in the early years of life and behave in a clinically aggressive manner, but vary somewhat in their microscopic appearance. Several groups have reported examples of an embryonal tumor with combined histologic features of ependymoblastoma and neuroblastoma, a lesion referred to as "embryonal tumor with abundant neuropil and true rosettes" (ETANTR). Herein, we present 22 new cases, and additional clinical follow-up on our 7 initially reported cases, to better define the histologic features and clinical behavior of this distinctive neoplasm. It affects infants and arises most often in cerebral cortex, the cerebellum and brainstem being less frequent sites. Unlike other embryonal tumors of the CNS, girls are more commonly affected than boys. On neuroimaging, the tumors appear as large, demarcated, solid masses featuring patchy or no contrast enhancement. Five of our cases (18%) were at least partly cystic. Distinctive microscopic features include a prominent background of mature neuropil punctuated by true rosettes formed of pseudo-stratified embryonal cells circumferentially disposed about a central lumen (true rosettes). Of the 25 cases with available follow-up, 19 patients have died, their median survival being 9 months. Performed on 2 cases, cytogenetic analysis revealed extra copies of chromosome 2 in both. We believe that the ETANTR represents a histologically distinctive form of CNS embryonal tumor. ©2009 by Lippincott Williams & Wilkins
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
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
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