1,721,154 research outputs found
Circulating tumour DNA as a biomarker in resectable and irresectable stage IV colorectal cancer; a systematic review and meta-analysis
No full textBackground: For patients with metastatic colorectal cancer, stratification for treatment (surgery or chemotherapy) is often based on crude clinicopathological characteristics like tumour size and number of lesions. Circulating tumour DNA (ctDNA) acts as a potential biomarker of disease trajectory and biology, allowing better stratification. This study aims to systematically review ctDNA in stage IV colorectal cancer to assess its potential role as a prospective biomarker to guide management decisions. Methods: A literature search was performed to identify studies where the measurement of ctDNA in stage IV colorectal cancer was correlated with a clinical outcome (radiological response, secondary resection rate, PFS, DFS or OS). Results: Twenty-eight studies were included, reporting on 2823 patients. Circulating tumour DNA was detectable in between 80% and 90% of patients prior to treatment. Meta-analysis identified a strong correlation between detectable ctDNA after treatment (surgery or chemotherapy) and overall survival (HR 2.2, 95% CI 1.79–2.69, p < 0.00001), as well as progression-free survival (HR 3.15, 95% CI 2.10–4.73, p < 0.00001). ctDNA consistently offered an early marker of long-term prognosis in irresectable disease, with changes after one cycle of systemic therapy demonstrating prognostic value. In resectable disease treated with curative intent, detection of ctDNA offered a lead time over radiological recurrence of 10 months. Conclusion: Circulating tumour DNA is detectable in the majority of resectable and irresectable patients. The presence of ctDNA is clearly associated with shorter overall survival, with changes in ctDNA an early biomarker of adverse disease behaviour. Prospective trials are essential to test its clinical efficacy.</p
Molecular, physiological, and biochemical properties of sclerotia metamorphosis in Rhizoctonia solani
No full text11 p.-4 fig.-1 tab.Rhizoctonia solani Kuhn (Basidiomycota, Cantharellales) is the main causal agent of rice sheath blight (RSB), which causes serious yield losses worldwide. The lack of rice varieties with resistance against RSB, which has a high sclerotia (dense masses of hyphal cells that function as compact survival structures in the fungal life cycle, enabling the fungus to endure adverse conditions and serve as reservoirs for subsequent growth and reproduction) survival rate, and the wide host range of R. solani, create basic challenges in the control of RSB. Overwinter sclerotium is the primary source of infection during the tillering stage of rice growth. In R. solani, a loose type of sclerotia is present. The sclerotia are primarily formed of compact masses of monilioid cells, but they may also be composed of undifferentiated hyphae. Three stages of sclerotial metamorphosis process are based on phenotypic changes, including the mycelium stage, the initial sclerotia stage (formation of monilioid cells), and sclerotia maturation. The metamorphosis of sclerotia involves the energy metabolism pathways and signal transduction pathways in the cell. In addition, there is evidence that the expression of genes encoding cell cycle activities may be important for sclerotia formation. During sclerotia metamorphosis, R. solani significantly expresses genes that encode antioxidants and respond to stimuli. The oxidative bursts begin in the initial sclerotia metamorphosis stage; at this time, reactive oxygen species (ROS) are mostly produced at the hyphal branches. In this sense, two classes of proteins related to glycosyltransferases B and the RNA recognition motif superfamily play a critical role in the sclerotial metamorphosis process in R. solani as scavengers of free radicals. The analysis of metabolic differences during sclerotia metamorphosis indicates that the NO metabolism may play an important role in sclerotia metamorphosis. Moreover, an increase in glycerophosphoethanolamines (PE) and glycerophosphoserines (PS) levels may indicate an advanced state of differentiation in mature R. solani sclerotia. Understanding the mechanisms involved in the sclerotial metamorphosis of R. solani can introduce new strategies for the management of RSB. In this review, we discuss the putative signaling and regulation mechanisms (such as quorum sensing) involved in the metamorphosis of sclerotia.Peer reviewe
Estudio de la formación de biofilms mixtos con microorganismos de interés industrial
No full text1 p.-2 fig.Los biofi lms consisten en estructuras adheridas a una superfi cie viva o inerte, integradas por microorganismos que normalmente producen una matriz extracelular polimérica y que pueden comunicarse
entre ellos. La formación del biofi lm es un proceso que suscita mucho interés debido,sobre todo, a la resistencia que confi ere a las células que lo integran frente a diversos estreses (temperatura, pH, antibióticos). Sin embargo, la formación de biofi lms entre distintos microorganismos(biofilm mixtos) con potencial biotecnológico no ha sido tan estudiada.
En este trabajo se ha probado la capacidad de formación de biofi lms en medio rico y presencia de oxígeno de distintas especies de hongos y bacterias con interés biotecnológico. Se han cuantificado los biofi lms formados por estos microorganismos sobre superfi cies plásticas, tanto de manera individual como en consorcios, usando el método de tinción con cristal violeta y apoyándose en imágenes obtenidas por microscopía electrónica de barrido (SEM). Los microorganismos utilizados han sido previamente descritos como degradadores de biomasa lignocelulósica(Ophiostoma piceae, Talaromyces amestolkiae) o como productores de compuestos con interés industrial (Yarrowia lipolytica, Saccharomyces cerevisiae, Pseudomonas putida o Escherichiacoli). Igualmente se ha testado un microorganismo electrogénico, con capacidad de donar electrones a un electrodo (Shewanella oneidensis).
En algunos consorcios, especialmente en los formados por hongo filamentoso y bacteria, se ha observado que las interacciones entre ambos microorganismos potencian la formación de biofilm. Estos biofilms mixtos presentan un gran potencial en fermentaciones diseñadas para realizar en un solo paso distintos procesos, como biorremediación y/o de moléculas con interés biotecnológico, contribuyendo a fomentar la economía circular.La financiación para la realización de este proyecto proviene del Consejo Europeo de Innovación (EIC) (HORIZON-EIC-2022-PATHFINDERCHALLENGES-01) bajo el acuerdo de financiación ID 101114746.Peer reviewe
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
Insight on the cellular signaling mechanisms in Yarrowia lipolytica strains
No full text1 p.-4 fig.Yarrowia lipolytica is a very interesting tool to produce value-added products in industry, mainly due to its biotechnological characteristics such as the secretion of proteins and organic acids, the accumulation of high amounts of intracellular lipids and its tolerance to several stresses. This yeast has also been used in bioremediation processes due to its ability to grow on hydrophobic carbon sources such as recalcitrant alkanes. To optimize the use of Y. lipolytica in industrial fermentation processes, not only in individual cultures but also in microbial consortia, here we explore the potential cell to cell signaling mechanisms in this species, in particular the putative quorum sensing (QS) systems. The QS phenomenon is a cell density-dependent signaling mechanism by which microorganisms communicate with each other through the secretion and detection of specific molecules. This mechanisms has been described in other yeasts, such as Candida albicans and Saccharomyces cerevisiae, which regulates yeast-hyphae morphological transition or biofilm formation, involving signals molecules such as farnesol, tryptophol, and 2-phenylethanol. Also, the genetic basis of this mechanism has been studied, and, besides its complexity, some specific genes stand out for their central role in this process, as the adenylyl cyclase Cyr1p in C. albicans. Here, we explore the potential signaling mechanisms in Y. lipolytica by assaying the phenotypic effect on different signal molecules and cell population concentrationPeer reviewe
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
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