1,721,036 research outputs found
Corticosteroids protect oligodendrocytes from cytokine-induced cell death
No full textThe present data show that the simultaneous exposure to tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) induces cell death with characteristics of apoptosis in cultured rat oligodendrocytes; TNFalpha alone was ineffective. We have also demonstrated that different corticosteroids (aldosterone, deoxycorticosterone, dexamethasone and corticosterone) protect rat oligodendrocytes in culture from apoptosis induced by TNFalpha plus IFNgamma. This effect seems to be exerted via the interaction with both type I and type II corticosteroid receptors since all steroids considered are effective. Since oligodendrocyte apoptosis represents an important event in multiple sclerosis and in several demyelinating diseases, the present observations might be considered an interesting background for further researches directed to the possibility of controlling in vivo the death of these cells
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
Fas/CD95-mediated apoptosis in human glioblastoma cells: a target for sensitisation to topoisomerase I inhibitors.
No full textThe expression of the death receptor Fas/CD95 is cell type-specific and can be modulated by different cytotoxic treatments. In spite of a frequent expression of Fas/CD95 in high-grade gliomas, these tumours are typically refractory to conventional therapy. Using a human glioblastoma cell line (GBM), we explored the possibility of modulating susceptibility to Fas/CD95-mediated apoptosis following cytotoxic treatment. GBM cells were sensitive to the antiproliferative effects of topoisomerase I inhibitors (topotecan and a novel lipophilic analog CPT83) and taxol, less sensitive to cisplatin and, in any case, rather resistant to drug-induced apoptosis. This pattern of cellular response was consistent with p53 mutation. GBM cells expressed low levels of Fas/CD95, which was associated with low susceptibility to antibody-stimulated Fas/CD95-mediated apoptosis. A significant up-regulation of Fas/CD95 expression was detected after exposure to topotecan and CPT83, whereas cisplatin induced a low increase and taxol did not modify Fas/CD95 expression. In addition, after treatment with topoisomerase I inhibitors, the up-regulation of Fas/CD95 resulted in an increased susceptibility of GBM cells to antibody-stimulated Fas/CD95-mediated apoptosis, while no synergistic effects were detected after treatment with cisplatin or taxol. Our data suggest that Fas/CD95 up-regulation can be a common response to DNA damage, whereas sensitisation to Fas/CD95-mediated apoptosis appears to be dependent on the type of DNA damage and on the pathway of cellular response. The observed effects might have important therapeutic implications for the design of novel therapeutic strategies in the treatment of malignant gliomas
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
CD45+/CD133+ positive cells expanded from umbilical cord blood expressing PDX-1 and markers of pluripotency
No full textHuman umbilical cord blood (UCB) contains cells able to differentiate into nonhaematopoietic cell lineages. It also contains cells similar to primitive embryonic stem cells (ESCs) that can differentiate into pancreatic-like cells. However, little data has been reported regarding the possibility of expanding these cells or their differential gene expression occurring in vitro. We expanded previously frozen UCB cells by treatment with Stem Cell Factor (SCF) and Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) in the presence of valproic acid (VPA). Gene expression profiles for beta-cell differentiation and pluripotency (embryo stem cell phenotype) were analysed by RT-PCR and immunocytochemistry. There was a dramatic expansion ( <150 fold) of hematopoietic progenitors (CD45+/CD133+) that also expressed embryo markers of pluripotency (nanog, kfl-4,sox-2,oct3/4 and c-myc), nestin, pancreatic markers as pax-4, ngn-3, pdx-1 and syt-1. UCB cells can be expanded to produce large numbers of cells of hematopoietic lineage that naturally (without retroviral vectors or transposons) express a gene pattern compatible with endocrine pancreatic precursors and markers of pluripotency. Our results confirm that frozen UCB cells can be dramatically expanded along the hematopoietic cell lineage (CD45+/CD133+) which express both markers of pluripotency and a gene pattern compatible with endocrine pancreatic precursors
A mesenchymal stromal cell line resistant to paclitaxel that spontaneously differentiates into osteoblast-like cells
No full textThe mesenchymal stromal cell line SR-4987 has been established in our laboratory from the bone marrow of BDF/1 mice. Recent information on mesenchymal stem cells biology and the need to deal with well-characterized cell lines suggest to critically consider the existent data on this cell line by updating them with new investigations on growth parameters, in vitro plasticity, and drug sensitivity to anti-cancer, anti-inflammatory, and a histone deacetylase inhibitor. SR-4987 cells show a population doubling time of 24.5 ± 5.4 h, a plating efficiency of 2.87 ± 1.19%, and under stimulation maintain only in part their multipotency by differentiating towards chondro-osteogenic lineages but not into adipogenic. Surprisingly, these mesenchymal stromal cells differentiate spontaneously into osteoblast-like cells and this is significantly stimulated by valproic acid. SR-4987 cells show a dramatic resistance to paclitaxel (PTX) with a resistance index of 39.6 times (evaluated versus MOLT-4 leukemia) and of 68.2 (versus HT-29 colorectal carcinoma). SR-4987 resistance is reversed by verapamil and correlates with high expression of P-glycoprotein that is down-modulated by PTX. Taken together, our results indicated that SR-4987 line is a very interesting cell model useful to investigate both drug sensitivity resistance and physiopathological aspects related to mesenchymal cell function
ZAP-70 and Syk expression in canine lymphoid cells and preliminary results on leukaemia cases
No full textZeta-chain-associated protein (ZAP-70) and spleen tyrosine kinase (Syk) are
structurally and functionally homologous tyrosine kinases playing a role in the
T- and B-cell signal transduction. Their activation can lead to lymphokine
production, cytolitic activity, antibody secretion, cell proliferation,
differentiation, survival and phagocytosis. Anomalous ZAP-70 and Syk expression
is reported to be related to tumor formation and progression, and ZAP-70
immunoreactivity is a good prognostic marker of disease progression in human
chronic lymphocytic leukaemia (CLL). Until now, to our knowledge, there are no
reports about canine ZAP-70 and Syk expression profiles. In the present study, a
RT-PCR procedure for the quali-quantitative evaluation of canine ZAP-70 and Syk
transcripts was designed. The expression patterns of canine ZAP-70 and Syk mRNAs
were evaluated in canine leukocyte subpopulations and in peripheral whole blood
samples from healthy dogs and from dogs with different types of leukaemia.
Similarly to humans, normal canine CD4+ and CD8+ T cells showed high expression
of ZAP-70, whereas Syk was abundantly expressed in normal CD21+ B cells. The
expression profile of ZAP-70 and Syk was markedly different in canine normal and
leukaemic blood. Decreased Syk expression was detected in dogs with T-cell CLL,
whereas decreased ZAP-70 expression was detected in dogs with B-cell CLL and
B-cell acute lymphocytic leukaemia (ALL). The comparison of ZAP-70 and Syk mRNA
levels between normal and leukaemic peripheral whole blood showed that the
expression ratio ZAP-70/Syk is subjected to modification depending on the
leukaemia status of patients. The results of the present work open an interesting
topic for leukaemogenesis investigation and are the basis for further studies for
a proper evaluation of the potential utility of these parameters for the
diagnosis and prognosis of canine T- and B-cell leukaemia
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