1,720,963 research outputs found
Developing new biotechnological tools to improve transgene expression in pig: Generating a pig primary cell line containing lox sites for efficient Recombinase-mediated cassette exchange (RMCE) and a human replicator to prevent gene silencing
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Tumor necrosis factor alpha down-regulates c-myc mRNA expression and induces in vitro monocytic differentiation in fresh blast cells from patients with acute myeloblastic leukemia.
No full textWe have studied tumor necrosis factor alpha (TNF-alpha) for its capacity to induce differentiation and to modulate c-myc and c-fms protooncogene mRNA expression in fresh blasts from 10 patients with acute myeloblastic leukemia (AML). Bone marrow blast cells were grown in suspension cultures in the presence of 500 U/ml (62 ng/ml) of TNF-alpha for 7 days. Induction of differentiation was assessed by means of morphology, cytochemistry, immunophenotyping (CD11b, CD13, CD14, CD33), and nitroblue tetrazolium reduction. In all cases, exposure of leukemic blasts to TNF-alpha resulted in phenotypic changes consistent with induction of differentiation, although a marked variability in degree and type of response was observed. The majority of cases developed monocytic morphology and showed significant increases (chi 2 test, p less than 0.05) in phagocytic activity and/or expression of ANAE and myelomonocytic differentiation antigens (CD11b, CD14). TNF-alpha reduced c-myc mRNA level over a period of 24 hr in four of six cases studied: the two cases with no down-regulation were the least responsive in terms of myelomonocytic differentiation. These results confirm those obtained with leukemic cell lines, suggesting that TNF-alpha can induce differentiation of fresh AML blasts, mainly toward the monocytic lineage, and that induction of differentiation seems to be closely linked to down-regulation of c-myc mRNA expression over the first 24 hr rather than to attenuation of cellular proliferation per se
Tumor necrosis factor alpha modulates the messenger RNA expression of hematopoietic growth factor genes in fresh blast cells from patients with acute myeloblastic leukemia.
No full textTumor necrosis factor alpha (TNF-alpha) has been previously shown to modulate the expression of hematopoietic growth factor genes in monocytes and other mesenchymal cells. As acute myeloblastic leukemia (AML) blasts can express and produce hematopoietic growth factors, the influence of TNF-alpha on the accumulation of mRNAs for c-myc, interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF, IL-6 and IL-1 beta was evaluated in fresh blasts from 13 patients with AML. Total cellular RNA was extracted from blast cells cultured for 24 hours with or without TNF-alpha (500 U/ml). The c-myc transcript level was decreased by TNF-alpha treatment in 9/13 cases, and increased in only one case. Among the growth factor genes, the GM-CSF gene was more often and consistently influenced by TNF-alpha, increased levels of its transcript being observed in 6/13 cases following treatment with the cytokine; in no case was there a reduction of GM-CSF mRNA. G-CSF and IL-6 transcripts were more heterogeneously influenced, whereas the IL-3 transcript was never detected in our AML samples. The IL-1 beta message was present in 8/13 untreated and in 13/13 TNF-alpha treated samples. Moreover, in untreated cells, GM-CSF, G-CSF and IL-6 expression was always associated with IL-beta expression. These findings indicate that TNF-alpha can modulate the levels of growth factor transcripts in AML blasts, and raise questions about the effects of TNF-alpha on leukemic hematopoiesis, considering that TNF-alpha, IL-1 and GM-CSF can synergistically stimulate the growth of AML clonogenic cells
DNA-protein interaction dynamics at the Lamin B2 replication origin
No full textTo date, a complete understanding of the molecular events leading to DNA replication origin activation in mammalian cells still remains elusive. In this work, we report the results of a high resolution chromatin immunoprecipitation study to detect proteins interacting with the human Lamin B2 replication origin. In addition to the pre-RC component ORC4 and to the transcription factors USF and HOXC13, we found that 2 components of the AP-1 transcription factor, c-Fos and c-Jun, are also associated with the origin DNA during the late G1 phase of the cell cycle and that these factors interact with ORC4. Both DNA replication and AP-1 factor binding to the origin region were perturbed by cell treatment with merbarone, a topoisomerase II inhibitor, suggesting that DNA topology is essential for determining origin function
HMGI(Y) and HMGI-C genes are expressed in neuroblastoma cell lines and tumors and affect retinoic acid responsiveness
No full textHMGI-C and HMGI(Y) are architectural DNA-binding proteins that participate in the conformational regulation of active chromatin. Their pattern of expression in embryonal and adult tissues, the analysis of the "pygmy" phenotype induced by the inactivation of the HMGI-C gene, and their frequent qualitative or quantitative alteration in experimental and human tumors indicate their pivotal role in the control of cell growth, differentiation, and tumorigenesis in several tissues representative of the epithelial, mesenchymal, and hematopoietic lineages. In contrast, very little information is available on their expression and function in neural cells, Here, we investigated the expression of the HMGI(Y) and HMGI-C genes in neuroblastoma (NB), a tumor arising from an alteration of the normal differentiation of neural crest-derived cells and in embryonal and adult adrenal tissue. Although HMGI(Y) is constitutively expressed in the embryonal and adult adrenal gland and in all of the NE cell lines and ex vivo tumors examined. its regulation appears to be associated to growth inhibition and differentiation because we observed that HMGI(Y) expression is reduced by retinoic acid (RA) in several NR cell lines that are induced to differentiate into postmitotic neurons, whereas it is up-regulated by RA in cells that fail to differentiate. Furthermore, the decrease of HMGI(Y) expression observed in R4-induced growth arrest and differentiation is abrogated in cells that have been made insensitive to this drug by NMYC overexpression. In contrast, HMGI-C expression is down-regulated during the development of the adrenal gland, completely absent in the adult individual. and only detectable in a subset of ex vivo NE tumors and in RA-resistant NE cell lines. We provide evidence of a causal link between HMGI-C expression and resistance to the growth arrest induced by Ri in NE cell lines because exogenous HMGI-C expression in HMGI-C-negative and RA-sensitive cells is sufficient to convert them into RA-resistant cells. Therefore, we suggest that HMGI-C and HMGI(Y) may participate in growth- and differentiation-related tumor progression events of neuroectodermal derivatives
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
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