1,720,968 research outputs found
Identification of novel therapeutic targets for high risk neuroblastoma patients: development of a lentiviral shRNA screen
No full textTrotz intensiver Forschung an Radiochemotherapieschemata liegt die
5-Jahresüberlebensrate von Kindern mit Neuroblastom vom Hochrisikotyp noch
immer bei nur 50%. Ein neuer, vielversprechender Ansatz ist die Kombination
konventioneller Therapieprinzipien mit der spezifischen Inhibition zellulärer
Signalwege, die für Tumorigenese verantwortlich sind. Imatinib ist ein
Beispiel für dieses Konzept, das die 5-Jahresüberlebensrate von Patienten mit
Chronisch Myeloischer Leukämie von 30% auf 89% verbesserte. Das Ziel dieser
Arbeit war die Entwicklung eines synthetischen RNA-Interferenzscreens
basierend auf einer Neuroblastomzelllinie mit hoher Doxorubicinresistenz und
die Durchführung einer Pilotstudie zur Identifizierung potentieller
therapeutischer Ziele für die Behandlung des Neuroblastoms. Im Rahmen dieser
Arbeit wurde ein auf Durchflusszytometrie basierter Assay entwickelt, der mit
SH-EP als Reporterzelllinie die Identifizierung von shRNA-mir-
Expressionsvektoren erlaubt, die Neuroblastomzellproliferation verringern oder
Doxorubicin induzierten Zelltod erhöhen. SH-EP Zellen wurden mit pGIPZ
lentiviralen shRNA-mir Expressionsvektoren transduziert und anschließend drei
Tage lang mit Puromycin selektioniert. Nach weiteren drei Tagen Wachstum +/-
Doxorubicin wurden DNA-Gehalt und Zellviabilität mittels Durchflusszytometrie
und dem Zellvitalitätstest MTT bestimmt. shRNA-mir-Expressionsvektoren gegen
PLK1 und p53 wurden als Positivkontrollen etabliert, die Zellproliferation
inhibieren und Zelltod verstärken, bzw. Doxorubicinresistenz erhöhen. Die
Fähigkeit des Systems, therapeutische Ziele zu identifizieren, wurde mit 275
shRNA-mir-Expressionsvektoren gegen 69 Gene der Familie der F-box Proteine,
Schlüsselregulatoren zellulärer Signalwege, exemplarisch nachgewiesen. Dieser
Screen war in der Lage, drei Gene zu identifizieren, von denen bekannt ist,
dass sie eine Rolle in der Pathogenese des Neuroblastoms spielen: Fbxo5/Emi1,
Fbxw11/β-TrCP2 und Fbxo45. Der Assay wies eine hohe Trennschärfe auf, da der
Unterschied zwischen dem Signal der Positivkontrollen und dem Median
regelmäßig mehr als 2σ betrug. Aufgrund dieser erfolgreichen Pilotstudie
scheint es nun sinnvoll, weitere Genfamilien, deren Mitglieder bekanntermaßen
Schlüsselpositionen in wachstumsregulierenden Signalwegen besetzen, mit dem
entwickelten System zu untersuchen. Die Herausforderung besteht darin, den
Durchsatz des Systems dadurch zu erhöhen, Durchflusszytometrie mit einem
ähnlich sensitiven, aber weniger zeitaufwändigen Read-out zu ersetzen, wie zum
Beispiel automatisierter Mikroskopie oder einem Fluoreszenz basierten
Reportersystem. Damit wird es möglich sein, die Fragestellung des Screens
auszuweiten und die Suche nach neuen therapeutischen Zielen für Patienten mit
Neuroblastom vom Hochrisikotyp zu beschleunigen.Even after extensive research on radiochemotherapy, the 5-year survival rate
of children with high risk neuroblastoma still does not exceed 50%. A
promising, new approach is the combination of conventional therapies with
specific inhibition of cell signaling that promotes tumorigenesis. Imatinib
set an impressive example for this concept by increasing the 5-year survival
rate of chronic myeloic leukemia patients from 30% to 89%. In order to
identify genes that could be inhibited to improve the therapeutic outcome of
high risk neuroblastoma patients, we sought to establish an RNA-interference
based synthetic lethal screen, using a highly doxorubicin resistant
neuroblastoma cell line. We developed a flow cytometry-based assay, which
enables the identification of shRNAmir expression vectors that reduce tumor
cell proliferation or augment doxorubicin-induced cell death, employing SH-EP
as neuroblastoma reporter cell line. SH-EP cells transduced with pGIPZ
lentiviral shRNAmir expression vectors were selected with puromycin for three
days. After subsequent growth in fresh medium +/-doxorubicin for three days,
cell cycle distribution and cell viability were measured using flow cytometry
and MTT assay. shRNAmir expression vectors targeting PLK1 and p53 were
established as positive controls that markedly inhibit cell proliferation and
increase cell death, or elevate doxorubicin resistance, respectively. The
capacity of the system to identify potential therapeutic targets was assessed
by knocking down the family of F-box proteins, key regulators of cellular
signaling, using 275 shRNAmir expressions vectors targeting 69 genes. This
screen recapitulated three genes known to play a role in neuroblastoma:
Fbxo5/Emi1, Fbxw11/β-TrCP2 and Fbxo45. The employed positive controls, being
more than two standard deviations from the mean, indicated the desirably high
sensitivity of the assay. This successful pilot study now rationalizes a knock
down strategy of larger groups of genes related to tumorigenesis, such as
phosphatases and kinases. One major challenge will be to increase the
throughput of the system by replacing flow cytometry with an equally sensitive
but less time-consuming read-out, like automated microscopy or a fluorescence
based reporter assay. This will allow broadening the scope of the screen and
accelerate the quest for new drugable targets to increase the chance of
successfully treating high risk neuroblastoma patients
Leukämie- und Immunzell-Koevolution in hämatologischen Neoplasien
Full text linkHigh-risk blood malignancies such as acute myeloid leukemia or advanced
chronic lymphocytic leukemia remain difficult-to-treat clinical challenges.
Immunotherapies including allogeneic stem cell transplantation or targeted
immunomodulation using immune checkpoint blockade can provide long-term disease
control, but their success rate is still not satisfactory. Single cell genomics is an
approach that can effectively monitor immune and leukemia cell dynamics by
providing detailed insight into changes in cellular compositions, cell states and
interactions. This work provides examples how integrated immune and leukemia
monitoring at single cell resolution reveals the determinants of response or non-
response to immunotherapy and tracks the clonal evolution of malignant cell
populations as therapeutic resistance develops. It also furthers the toolkits available
to us by extending standard single cell RNA sequencing with targeted genotyping and
explores the ability to utilize mitochondrial DNA mutations as an alternative natural
barcoding system for the study of leukemic subclones. Together, this sets the stage
for more stream-lined single cell studies that foreshadow the adoption of these
technologies into clinical hematologic practice
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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