1,720,972 research outputs found
Bovine serum amine oxidase and spermine cause apoptosis in cancer cells detected by flow cytometry, real time RT-PCR and proteomic analyses
No full textNeuroblastoma (NB) is the most common cancer in infancy and most frequent cause of death from extracranial solid tumors in children. Therefore, besides the current treatments that include chemotherapy, surgery, and radiation, new therapies need to be developed. The in situ formation of cytotoxic polyamine metabolites by bovine serum amino oxidase (BSAO) is a recent approach in cancer therapy. It was demonstrated that BSAO and spermine (SPM) addition to cancer cells induces cell growth inhibition by apoptosis caused by H2O2 and aldehydes, produced by the oxidative reaction. The induction of apoptosis in NB cells was evaluated by flow cytometry after Annexin V-FITC labelling and DNA staining with propidium iodide. The percentages of Annexin V-positive cells matched quite well with that of cells showing hypodiploid sub-G1 peak. An increase in mitochondrial membrane depolarization (MMD) was found in neuroblastoma cells treated with the enzymatic system. We analysed by real time RT-PCR the transcript of some genes involved in the apoptotic process, to determine possible down or up regulation of mRNAs after the treatment of the SJ-N-KP cell line with BSAO and SPM. The experiments were carried out considering the pro-apoptotic genes P53, PUMA and CASPASE-3. After treatment with BSAO and SPM, the SJ-N-KP cells displayed increased mRNA levels for all these pro-apoptotic genes. Interestingly, the pro-apoptotic Sirt-1 inhibitor microRNA miR-34a significantly increases in SJ-N-KP cells treated with BSAO and SPM. These data support the concept that BSAO/SPM treatment induces high levels of apoptosis. Previously we demonstrated that multidrug resistant (MDR) colon adenocarcinoma cells (LoVo DX) are more sensitive than the corresponding wild type cells (LoVo WT) to H2O2 and aldehydes. Transmission electron microscopy observations showed evident mitochondria alterations. The mitochondrial activity was checked by flow cytometry studies, labelling cells with the probe JC1. After treatment with BSAO/SPM the cells showed a marked increase in MMD. In order to have more information on the effect of BSAO/SPM in cancer cells, a proteomics approach was performed using LoVo cells and prostate cancer (LNCaP) cells treated with and without BSAO/SPM. In total 721 unique proteins were identified in LNCaP cells (more than 4700 in LoVo cells) of which 40 were differentially expressed by more than 1.3 folds. The canonical pathways that exhibited the largest differences between BSAO treated and untreated cells in the presence of SPM include mitochondrial dysfunction. We conclude that the mechanism of the cytotoxicity of BSAO/SPM is partly related to mitochondrial dysfunction
Polyamine metabolites induce apoptosis in cancer cells detected by real time RT-PCR and mass spectroscopy analyses
No full textIn situ formation of cytotoxic polyamine metabolites by an enzyme-catalyzed reaction is a recent approach in cancer chemotherapy. We demonstrate that multidrug resistant (MDR) colon adenocarcinoma cells (LoVo DX) are more sensitive than the corresponding wild type cells (LoVo WT) to H 2 O 2 and aldehydes, the products of bovine serum amine oxidase (BSAO)-catalyzed oxidation of spermine (SPM). Both cytotoxic metabolites were responsible for the loss of cell viability. Transmission electron microscopy observations showed that BSAO and SPM induced evident mitochondria alterations, more pronounced in LoVo DX than in LoVo WT cells. The mitochondrial activity was checked by flow cytometry studies, labelling cells with the probe JC1, that displayed a basal hyperpolarized status of the mitochondria in LoVo DX cells. After treatment with BSAO and SPM, the cells showed a marked increase in mitochondrial membrane depolarization (MMD), higher in LoVo DX than in LoVo WT cells. An increasing in MMD was also found in neuroblastoma SJ-NKP cell line treated with BSAO and 18 μM SPM concentration. We analysed by real time RT-PCR the transcript of some genes involved in the apoptotic process, to determine possible down or up regulation of mRNAs after the treatment of SJ- NKP cell line with BSAO and SPM. Experiments were carried out considering the pro- apoptotic genes P53, PUMA and CASPASE-3. After treatment with BSAO and SPM, the SJ-NKP cells displayed increased mRNA levels for all these pro-apoptotic genes. Interestingly, the pro-apoptotic Sirt-1 inhibitor microRNA miR-34a significantly increases in SJ-NKP cells treated with BSAO and SPM. These data support the concept that BSAO/SPM treatment induces high levels of apoptosis. In order to have more information on the effect of BSAO and SPM in tumor cells, a proteomics approach was performed using LoVo cells and prostate cancer (LNCaP) cells treated with and without BSAO/SPM. In total 721 unique proteins were identified in LNCaP cells (more than 4700 in LoVo cells) of which 40 were differentially expressed by more than 1.3 folds. The diseases and biofunctions analyses in the heat map show increase in cell death of tumor cells. The canonical pathways that exhibited the largest differences between BSAO treated and untreated cells in the presence of SPM include both mitochondrial dysfunction and eIF-2 signaling. Therefore, we conclude that the mechanism of the cytotoxicity of BSAO/SPM is partly related to mitochondrial dysfunction
Retinoic acid modulates stem cell factor secretion by human neuroblastoma cell lines
No full textThe hemopoietin stem cell factor (SCF) and its receptor c-kit are expressed in some tumoral cells, including neuroblastoma (NB) cells. We have investigated the effect of retinoic acid (RA), one of the most active differentiating agents on human NB cells, on the SCF production by human neuroblastoma cell lines. SCF concentration was determined by immunoenzymatic assay in the supernatants of seven neuroblastoma cell lines. All cell lines except one showed detectable amounts of SCF in the supernatant in basal culture conditions. A progressive increase pattern of the SCF concentration over time, was common to all SCF secreting cell lines, both unstimulated and RA-stimulated. Moreover, after 48 and 72 hours-exposure to RA, SCF concentrations were higher than in the untreated controls (p<0.01). Membrane SCF mRNA isoform was also detected by reverse-transcription polymerase chain reaction. These effects demonstrated that RA, besides inducing neuronal differentiation, enhanced SCF production in neuroblastoma cell lines
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
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
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