1,720,988 research outputs found
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
Evaluation of Newcastle disease virus as an oncolytic agent in colorectal cancer cell lines
Get PDFReports showing tumour regression in cancer patients following viral infections appeared at the beginning of the last century. By the 1950s, several viruses including
Newcastle disease virus (NDV) showed positive oncolytic activities. Since then, NDV with its natural ability to infect cancer cells has been widely studied as a candidate in viral oncolysis. In the present study, oncolytic effect of a local NDV isolate, strain AF2240, was analysed in a panel of colorectal cancer (CRC) cell lines. Prior to infection studies, a modified plaque assay using CRC cells as hosts was established. SW620 was found to be the best cell line to be used for NDV plaque assay because of the size, clarity, and also the number of plaques formed. The plaque forming unit (pfu)/ mL of NDV was determined and subsequently used for the infection studies.
All the CRC lines underwent apoptosis upon NDV infection. The presence of syncytia, a characteristic of paramyxoviral infection, proved that these cells were indeed infected by the virus. In addition, sandwich ELISA and plaque assays performed on spent culture supernatants showed that infectious viral progenies were released into the medium.
The effects of NDV infection on the Ras/Akt/PKB pathway in these CRC cells with multiple gene mutations (in K-Ras, p53, and APC) were analysed. Comparison between these cell lines showed that all the cells experienced down-regulation of pAkt upon NDV infection. This down-regulation, however, did not affect its downstream effector, pGSK3β. Thus the β-catenin protein level was also not down-regulated in all the cells. It is not surprising, however, that the pGSK3β and β-catenin were down-regulated in the HCT116p53-/- cells as these cells possess wild type APC and the p53 gene is knocked out in both alleles. From these results, it is possible to suggest that it may not be effective to use therapeutic agents targeting the Ras/Akt/PKB pathway for CRC treatment. Regardless of the effect of NDV infection on the cell proliferation pathway, NDV did up-regulate BAD, down-regulate pBAD or reduce the Bax/Bcl-2 levels
(depending on the cell lines) leading to apoptosis in these cells.
The SW480 cells experienced a down-regulation of the pAkt during a primary infection (at 25 hpi or earlier) but recovered gradually during a secondary infection (after 25 hpi) when the pAkt level increased. Repeated exposures of NDV to these cells did not induce any cellular apoptosis. These cells were then labelled as SW480P as they were found to be persistently infected with the virus. Microscopic analysis of the SW480P, with or without re-infection of NDV, showed an identical physical appearance to that of the
parental SW480 cells. RT-PCR and immunofluorescent analyses of one of the most abundant NDV protein, the nucleocapsid protein (NP) showed that the viral RNA and proteins were present in the uninfected SW480P. However, the newly synthesized viral progenies showed smaller plaques compared to wild type NDV suggesting that defective interfering particles (DIP) were produced. This abortive infection resulting in the production of DIPs may explain why some cancer cells resist the oncolytic effect by the virus during virotherapy.
This study demonstrated the potential of NDV as an oncolytic agent in various CRC cell lines. NDV mediated the oncolysis through suppression of the Ras/Akt/PKB pathway
leading to apoptosis. Cellular apoptosis occur in CRC cells, regardless of the genetic mutations acquired, by the reduction of the Bax/Bcl-2 ratio, up-regulation of BAD and
down-regulation of pBAD. Despite the robust pro-apoptotic ability of NDV, a small percentage (17%) of cells in the infected population, survived the infection even after 97
hpi. Following rescue and further propagation, these cells were found to be persistently infected with NDV. Viral progenies were actively secreted into the culture media.
However, these secreted viruses were found to be less infectious and showing reduced oncolytic activities, characteristic of DIPs. Results obtained from this study will contribute towards further understanding of the mechanisms of NDV-induced oncolysis. This information will be useful for improving NDV as a candidate for cancer
virotherapy
Structural Analysis of a Peptide (CTLTTKLYC) that Interacts with Newcastle Disease Virus
Get PDFA peptide with the sequence Cys-Thr-Leu-Thr-Thr-Lys-Leu-Tyr-Cys (CTLTTKLYC)
has previously been identified to inhibit the propagation of Newcastle disease virus
(NDV) in embryonated chicken eggs and tissue culture. It has two different
dissociation constants (&"I), in which the first constant can be used as a determinant
to classifjr NDV strains into two groups: the velogenic strains in the first group,
whereas the mesogenic and lentogenic strains are in the second group. The peptide,
C 1T 2L3 P T5K 6 L7 Y8 C9 ,d isplayed on the pIII protein of a filamentous M13 phage was
mutated by oligonucleotide-directed mutagenesis in order to identify the amino acid
residues involved in the interactions with NDV. Mutations of Cys at first position
(c')a nd Lys at the sixth position of the peptide ( K ~t)o Ala (A), which produced
mutants C'A and K~Ad,i d not affect the binding between the peptide and the virus
significantly, but substitution of Tyr at eighth position (Y8) alone with Ala (A)
dramatically reduced the interaction. This suggests that y8 couid play an important
role in the peptide-virus interaction. Double mutations were carried out on K~ and y8
to produce mutants K~A-Y~AK,~ R-Y~AK,~ A-Y'F, and K ~ - Y ~ Fto, determine
whether the mutated amino acids could improve the binding capability. However, the
mutations did not improve the binding capability significantly.
Fmoc-solid phase peptide synthesis was employed to synthesize the peptide,
CTLTTKLYC. Crude peptide was purified with HPLC and analysed with a mass
spectrometer. The secondary structure of the peptide was analysed with circular
dichroism (CD) and the three dimensional conformation of the peptide was
determined by nuclear magnetic resonance (NMR) and molecular modelling. A
mixture conformation of p-turn and P-sheet (intermolecular interaction) was
observed for the linear peptide by using CD. However, the three-dimensional
structure of the linear peptide could not be arrived due to the mixture of
conformation which made the sequence assignment of NMR extremely difficult. On
the other hand, the disulfide-constrained cyclic peptide, which has a more rigid
structure, exhibited only a P-turn structure. Two models were obtained: one of it
consists of a p-turn and a distorted p-turn, while the other structure is an extended
structure
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
