1,720,968 research outputs found
Hypoxia mediates cancer development and progression through HIF-1a and microRNA regulation
Get PDFBackground: MicroRNAs (miRNAs) are small non coding RNAs which play a role in several cellular
processes such as apoptosis, cell differentiation, proliferation and stress response. Thus, changes in
miRNA expression are associated with the development and progression of human disease like
cancer and many other systemic diseases. MiRNAs expression could be influenced by different
stimuli such as oxidative stress, inflammatory response and hypoxia. Lately, some hypoxia-inducible
miRNAs (HRMs, hypoxia-regulated miRNAs) have been identified. These HRMs are often activated
in different types of cancers, suggesting their role in tumorigenesis.
Obstructive sleep apnea (OSA) is a breathing disorder characterized by recurrent obstructions of the
upper airway associated with increased inspiratory efforts, intermittent hypoxemia and sleep
fragmentation. Recent experiments suggest that cancer could be a disease associated with this sleep
breathing disorder. The mechanisms that regulate gene expression during hypoxia are not fully
understood but miRNAs expression seems to have an important role in various processes.
On these basis, the main aims of this experimental thesis are: i) to evaluate the roles of continuous
hypoxia (CH) and miRNAs in cancer; ii) to evaluate how hypoxia could influence the expression of
specific miRNAs in cells; iii) to assess the differences in the expression profile of specific miRNAs
induced by continuous and intermittent hypoxia; iv) to evaluate changes in miRNAs expression in
controls or patients affected by OSA and/or cancer and in colorectal cancer cells exposed to
intermittent hypoxia (IH), and to evaluate their impact on tumor progression in vitro.
Materials and Methods: For this purpose, I used qRT-PCR to detect miRNAs expression both CaCo2
cells exposed to CH or IH, to 2 to 24/32h, with or without acriflavine (ACF), a HIF-1 inhibitor and in
patients’ sera. MTT and transwell invasion test were applied to investigate the proliferation and
migration of CaCo2 exposed to IH and treated with miRNA inhibitors or ACF. HIF-1 activity was
evaluated in CaCo2 cells after IH.
Results: The levels of almost all analyzed miRNAs (miR-21, miR-23b, miR-26a, miR-27b, and miR-
145) were greater in continuous hypoxia versus normoxia. Furthermore, the expression of nearly all
miRNAs was higher in IH than in CH.
In addition, the levels of miR-21, miR-26a and miR-210 increased in OSA and ONCO-OSA patients
compared to controls. MiR-23b increased in ONCO-OSA patients, and miR-27b and miR-145
increased in OSA but not ONCO-OSA patients.
MiR-21, miR-26a, miR-23b and miR-210 increased in cells after IH. Proliferation and migration were
increased by IH and reduced after either miRNA inhibition or ACF treatment. MiRNA inhibition
reduces HIF-1α gene expression. Conversely, the expression of these miRNAs was significantly
decreased after ACF treatment.
Conclusions: We identified a series of miRNAs, induced by the hypoxic environment, in malignancies
associated with hypoxia, especially OSA-associated intermittent hypoxia.
These data would demonstrate that there is a different response between the condition of
intermittent versus chronic hypoxia, and the former appears to be much more harmful in terms of
stimulation of the expression of some miRNAs. These miRNAs could be implicated in cancer
development and progression through a regulatory loop involving HIF-1
Effects of a Tennis Match on Perceived Fatigue, Jump and Sprint Performances on Recreational Players
Get PDFBackground: Tennis is an intermittent sport, characterized by hundreds of repetitive explosive efforts, including accelerations, and jumps. A single match can last up to 5 hours and players are called to play several matches often separated by less than 48h of recovery. Objective: The study aimed to investigate the effects of a standardized tennis match on perceived fatigue and jump and sprint performances on a group of recreational tennis players and to observe if such variables were affected by residual effects of fatigue 24 hours after the match. Methods: Twelve recreational tennis players performed a 120 min match. Before, immediately after and 24h after the match, players completed a set of three countermovement jumps, three 10m sprints, and reported their perception of general fatigue. Results: Significant differences between the three conditions have been found for the perceived fatigue: indeed fatigue was higher both in the immediate post (F(1,10)= 54.422, η2 = 0.845, p<0.001) and 24h post-match (F(1,10)= 10.947, η2 = 0.523, p=0.08), with respect to the pre-match condition. No significant differences were detected in the other variables. Conclusion: During a tournament, the performance of tennis players may be weakened and the recovery prejudiced. To identify fluctuations of and factors linked to fatigue may help tennis practitioners to apply adequate recovery strategies with athletes, limiting performance decrements within a tournament, and indirectly preventing injuries
Different Expression of Micro-RNA in the Subcutaneous and Visceral Adipose Tissue of Obese Subjects
No full textObesity is a pathology characterized by an excessive accumulation of adipose tissue and it is a condition associated with complex alterations affecting different organs and systems. Obesity has great influences on cardiovascular and respiratory morbidity and mortality, and impairs the multiple aspects of metabolism. Since micro-RNAs (miRNAs) are thought to play a role in the regulation of various pathological processes, in this complex framework, the investigation of these classes of noncoding regulatory RNA seems to be promising. Selected group of obese subjects was recruited. We analyzed the expression of seven miRNAs from obese adipose tissue supposed to have a role in the pathogenesis of cardiovascular and respiratory disease related to obesity and we compared it with the expression of the same miRNAs in a group of nonobese controls. In this study what emerged is miR-27b and miR-483 significant downregulation in subcutaneous adipose tissue from obese group compared with nonobese ones. For visceral adipose tissue, a significant decrease in miR-27b and miR-223 expression was observed in obese group. Moreover, a different expression of miR-26a and miR-338 in the obese group was found. Those findings could help the individuation of previously unknown key players in the development of different diseases usually associated with obesity, such as cardiovascular and pulmonary diseases. Clinical Trials.gov ID: Ref 17/CE/2014
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
Obstructive Sleep Apnea: A Look towards Micro-RNAs as Biomarkers of the Future
No full textSleep-disordered breathing (SDB) includes a broad spectrum of diseases, of which obstructive sleep apnea syndrome (OSA) is the most clinically significant manifestation. OSA is a respiratory disorder characterized by episodes of complete or partial obstruction of the upper airways that disturb ventilation and sleep architecture. In recent years, interest in the clinical implications of OSA seems to have increased, probably due to the numerous studies that have shown the existence of an important correlation between OSA and cardiovascular, dysmetabolic, and neoplastic changes. The guidelines currently available highlight the importance of diagnosis and effective treatment for OSA, underlining the need for new biomarkers that are useful in clinical practice, feasible, and reproducible to guide medical decision making. In this review, we intend to provide an overview of the potential role of microRNAs as new indicators for OSA management. MicroRNAs (miRNAs) are small non-coding RNA molecules that play an important role in RNA silencing and regulation of gene expression at the post-transcriptional level. These can bind specifically to their target genes by forming silencing complexes, thus inducing degradation or altered gene expression. A wide range of miRNAs have been extensively studied in a variety of diseases including cancer, and recently, miRNAs have been shown to have enormous potential to function as diagnostic and clinical biomarkers of disease. This review includes recent studies that establish the inevitable role of miRNAs in the pathogenesis of OSA
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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