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Search Results: 1 - 10 of 294570 matches for " Rocio I. R. Macias "
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Cholangiocarcinoma: Biology, Clinical Management, and Pharmacological Perspectives
Rocio I. R. Macias
ISRN Hepatology , 2014, DOI: 10.1155/2014/828074
Abstract: Cholangiocarcinoma (CCA), or tumor of the biliary tree, is a rare and heterogeneous group of malignancies associated with a very poor prognosis. Depending on their localization along the biliary tree, CCAs are classified as intrahepatic, perihilar, and distal, and these subtypes are now considered different entities that differ in tumor biology, the staging system, management, and prognosis. When diagnosed, an evaluation by a multidisciplinary team is essential; the team must decide on the best therapeutic option. Surgical resection of tumors with negative margins is the best option for all subtypes of CCA, although this is only achieved in less than 50% of cases. Five-year survival rates have increased in the recent past owing to improvements in imaging techniques, which permits resectability to be predicted more accurately, and in surgery. Chemotherapy and radiotherapy are relatively ineffective in treating nonoperable tumors and the resistance of CCA to these therapies is a major problem. Although the combination of gemcitabine plus platinum derivatives is the pharmacological treatment most widely used, to date there is no standard chemotherapy, and new combinations with targeted drugs are currently being tested in ongoing clinical trials. This review summarizes the biology, clinical management, and pharmacological perspectives of these complex tumors. 1. Primary and Metastatic Liver Cancer Primary liver cancer accounts for approximately 10–12% of deaths due to cancer. Although the incidence of this group of cancers is lower than 6% of new cancers diagnosed each year worldwide, the prognosis is usually very poor. The most frequent of these tumors are adenocarcinomas, which include hepatocellular carcinoma (HCC) derived from parenchymal cells—accounting for almost 85% of liver adenocarcinomas and cholangiocarcinoma (CCA), derived from biliary epithelial cells and accounting for the remaining 15%. Other rare primary liver tumors include hemangiosarcoma, derived from endothelial cells, and hepatoblastoma, derived from embryonic or fetal hepatocyte precursors. Even less frequent primary liver cancers are fibrosarcoma and lymphosarcoma. It should also be considered that the liver is highly vulnerable to tumor invasion from extrahepatic metastasis. The large size of the liver, its abundant blood supply, and its double-source vascularization explain why it is the second most common seat of metastasis after lymph nodes. Among the tumors that most frequently metastasize to the liver are colorectal cancer, breast cancer, melanoma, and lung cancer. 2.
Excretion of biliary compounds during intrauterine life
Rocio IR Macias, Jose JG Marin, Maria A Serrano
World Journal of Gastroenterology , 2009,
Abstract: In adults, the hepatobiliary system, together with the kidney, constitute the main routes for the elimination of several endogenous and xenobiotic compounds into bile and urine, respectively. However, during intrauterine life the biliary route of excretion for cholephilic compounds, such as bile acids and biliary pigments, is very poor. Although very early in pregnancy the fetal liver produces bile acids, bilirubin and biliverdin, these compounds cannot be efficiently eliminated by the fetal hepatobiliary system, owing to the immaturity of the excretory machinery in the fetal liver. Therefore, the potentially harmful accumulation of cholephilic compounds in the fetus is prevented by their elimination across the placenta. Owing to the presence of detoxifying enzymes and specific transport systems at different locations of the placental barrier, such as the endothelial cells of chorionic vessels and trophoblast cells, this organ plays an important role in the hepatobiliary-like function during intrauterine life. The relevance of this excretory function in normal fetal physiology is evident in situations where high concentrations of biliary compounds are accumulated in the mother. This may result in oxidative stress and apoptosis, mainly in the placenta and fetal liver, which might affect normal fetal development and challenge the fate of the pregnancy. The present article reviews current knowledge of the mechanisms underlying the hepatobiliary function of the fetal-placental unit and the repercussions of several pathological conditions on this tandem.
Persistence of Anticancer Activity in Berry Extracts after Simulated Gastrointestinal Digestion and Colonic Fermentation
Emma M. Brown, Gordon J. McDougall, Derek Stewart, Gema Pereira-Caro, Rocio González-Barrio, Philip Allsopp, Pamela Magee, Alan Crozier, Ian Rowland, Chris I. R. Gill
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049740
Abstract: Fruit and vegetable consumption is associated at the population level with a protective effect against colorectal cancer. Phenolic compounds, especially abundant in berries, are of interest due to their putative anticancer activity. After consumption, however, phenolic compounds are subject to digestive conditions within the gastrointestinal tract that alter their structures and potentially their function. However, the majority of phenolic compounds are not efficiently absorbed in the small intestine and a substantial portion pass into the colon. We characterized berry extracts (raspberries, strawberries, blackcurrants) produced by in vitro-simulated upper intestinal tract digestion and subsequent fecal fermentation. These extracts and selected individual colonic metabolites were then evaluated for their putative anticancer activities using in vitro models of colorectal cancer, representing the key stages of initiation, promotion and invasion. Over a physiologically-relevant dose range (0–50 μg/ml gallic acid equivalents), the digested and fermented extracts demonstrated significant anti-genotoxic, anti-mutagenic and anti-invasive activity on colonocytes. This work indicates that phenolic compounds from berries undergo considerable structural modifications during their passage through the gastrointestinal tract but their breakdown products and metabolites retain biological activity and can modulate cellular processes associated with colon cancer.
Computational treatment of traveling-wave solutions of a population model with square-root dynamics
J. E. Macias-Diaz,I. E. Medina-Ramirez
Advanced Studies in Biology , 2013,
Abstract: Motivated by a recent report by R. E. Mickens, we design an efficient,non-standard, two-step, nonlinear, explicit, exact finite-differencemethod to approximate solutions of a population equation with squarerootreaction law. Mickens’ report establishes the existence of nonnegative,traveling-wave solutions of that model which are boundedfrom above by 1, and which are spatially and temporally monotone.As its analytic counterpart, the computational technique proposed inthe present manuscript is capable of preserving the non-negativity andthe boundedness of initial profiles under suitable and flexible conditionson the computational parameters. We provide theoretical results on theexistence and uniqueness of non-negative and bounded solutions of themethod, and we establish that our technique conditionally preserves thespatial and temporal monotonicity of the approximations. The numericalsimulations obtained through a computer implementation of ourfinite-difference scheme support the fact that the method preserves allof the mathematical characteristics of approximations mentioned above.
Cambios en las Herramientas Pedagógicas. Videos de casos sobre emprendimientos innovadores locales: Videos on innovating local entrepreneurial cases
Pedraza A,Aura Cecilia; Bravo I,Edna Rocio;
Revista EAN , 2011,
Abstract: the purpose of this study was to explore the results obtained when using videos on local entrepreneurial cases which complement the learning process in the subject called company creation at escuela de estudios industriales y empresariales de la universidad industrial de santander (uis). this quantitative study shows that the application of this teaching practice improves the students' perceptions on the successfulness of the learning process.
Measuring Cosmological Parameters with the JVAS and CLASS Gravitational Lens Surveys
P. Helbig,R. D. Blandford,I. W. A. Browne,A. G. de Bruyn,C. D. Fassnacht,N. Jackson,L. V. E. Koopmans,J. F. Macias-Perez,D. R. Marlow,S. T. Myers,R. Quast,D. Rusin,P. N. Wilkinson,E. Xanthopoulos
Physics , 1999,
Abstract: The JVAS (Jodrell Bank-VLA Astrometric Survey) and CLASS (Cosmic Lens All-Sky Survey) are well-defined surveys containing about ten thousand flat-spectrum radio sources. For many reasons, flat-spectrum radio sources are particularly well-suited as a population from which one can obtain unbiased samples of gravitational lenses. These are by far the largest gravitational (macro)lens surveys, and particular attention was paid to constructing a cleanly-defined sample for the survey itself and for the underlying luminosity function. Here we present the constraints on cosmological parameters, particularly the cosmological constant, derived from JVAS and combine them with constraints from optical gravitational lens surveys, `direct' measurements of $\Omega_{0}$, $H_{0}$ and the age of the universe, and constraints derived from CMB anisotropies, before putting this final result into the context of the latest results from other, independent cosmological tests.
Análisis del comportamiento de flujo de fluidos en un horno de reverbero agitado con diferentes impulsores, mediante la modelación física y numérica
Juárez, R.,Flores, A.,Macias, E.,Reyes, N.
Revista de Metalurgia , 2009,
Abstract: A fluid flow analysis and particle trajectory in a 5 t molten capacity scaled 1:2 model of a reverberatory furnace was performed using both physical and numerical simulation. The design of the system allowed studying the behavior of the liquid in a system agitated by impellers. The parameters studied were, rotating speed, shape and height of the impeller. The physical and numerical simulations were used to determine circulation and mixing times, fluid flow patterns and velocity profiles in the agitation and melting chambers. Using experimental data, it was possible to establish the interaction between turbulent flow and circulating solid particles. The original design of the reverberatory furnace was modified based on the physical and numerical simulation analysis. The new design showed an increased magnesium removal rate by means of a more efficient and faster mixing. Utilizando la simulación física y numérica, en este trabajo se presenta un análisis del flujo de fluidos y la trayectoria de partículas, en un modelo escala 1:2 de un horno de reverbero de 5 t. La caracterización del sistema sirvió para determinar el comportamiento del líquido en un sistema agitado mediante impulsores de diferentes formas rotando a diferentes velocidades y alturas, lo cual ha permitido determinar tiempos de circulación, de mezclado, patrones de flujo y patrones de velocidad en las cubas de agitación y fusión. Además, se aportan datos experimentales de la interacción entre flujos turbulentos y partículas sólidas. Los resultados obtenidos sugirieron cambios en la geometría del dise o de un horno convencional, propiciando mezclado más rápido y eficiente e incrementando la eficiencia en la remoción de magnesio.
MILCA, a Modified Internal Linear Combination Algorithm to extract astrophysical emissions from multi-frequency sky maps
G. Hurier,J. F. Macias-Perez,S. R. Hildebrandt
Physics , 2010, DOI: 10.1051/0004-6361/201321891
Abstract: The analysis of current Cosmic Microwave Background (CMB) experiments is based on the interpretation of multi-frequency sky maps in terms of different astrophysical components and it requires specifically tailored component separation algorithms. In this context, Internal Linear Combination (ILC) methods have been extensively used to extract the CMB emission from the WMAP multi-frequency data. We present here a Modified Internal Linear Component Algorithm (MILCA) that generalizes the ILC approach to the case of multiple astrophysical components for which the electromagnetic spectrum is known. In addition MILCA corrects for the intrinsic noise bias in the standard ILC approach and extends it to an hybrid space-frequency representation of the data. It also allows us to use external templates to minimize the contribution of extra components but still using only a linear combination of the input data. We apply MILCA to simulations of the Planck satellite data at the HFI frequency bands. We explore the possibility of reconstructing the Galactic molecular CO emission on the Planck maps as well as the thermal Sunyaev-Zeldovich effect. We conclude that MILCA is able to accurately estimate those emissions and it has been successfully used for this purpose within the Planck collaboration.
Stability and Unobstructedness of Syzygy Bundles
L. Costa,P. Macias Marques,R. M. Miró-Roig
Mathematics , 2009,
Abstract: It is a longstanding problem in Algebraic Geometry to determine whether the syzygy bundle $E_{d_1,..., d_n}$ on $\PP^N$ defined as the kernel of a general epimorphism $\xymatrix{\phi:\cO(-d_1)\oplus...\oplus\cO(-d_n)\ar[r] &\cO}$ is (semi)stable. In this note, we restrict our attention to the case of syzygy bundles $E_{d,n}$ on $\PP^N$ associated to $n$ generic forms $f_1,...,f_n\in K[X_0,X_1,..., X_N]$ of the same degree $d$. Our first goal is to prove that $E_{d,n}$ is stable if $N+1\le n\le\tbinom{d+2}{2}+N-2$. This bound improves, in general, the bound $n\le d(N+1)$ given by G. Hein in \cite{B}, Appendix A. In the last part of the paper, we study moduli spaces of stable rank $n-1$ vector bundles on $\PP^N$ containing syzygy bundles. We prove that if $N+1\le n\le\tbinom{d+2}{2}+N-2$ and $N\ne 3$, then the syzygy bundle $E_{d,n}$ is unobstructed and it belongs to a generically smooth irreducible component of dimension $n\tbinom{d+N}{N}-n^2$, if $N \geq 4$, and $n\tbinom{d+2}{2}+n\tbinom{d-1}{2}-n^2$, if N=2.
Tratamientos y dise os alternativos de las instalaciones de riesgo de proliferación de Legionella neumophila Alternatives treatment in the installations for legionellosis risk reduction
José Macias Macias
Revista de Salud Ambiental , 2006,
Abstract: La dilatada experiencia del autor en el campo de la ingeniería de mantenimiento hospitalario, ha servido de base para sugerir distintas alternativas para prevenir la aparición de la bacteria Legionella neumophila en las instalaciones de riesgo. Lo que se pretende con las recomendaciones propuestas de dise o, uso y tratamiento de dichas instalaciones, es crear en ellas entornos hostiles para la vida microbiana y especialmente para la legionela, combinando métodos físicos y químicos. De esta forma lograremos disminuir las poblaciones de la bacteria, por debajo de los niveles que a la luz de los conocimientos actuales, resultan infectivos. Se describen opciones diferentes a los métodos de tratamiento tradicionales, que permiten obtener los mismos resultados minimizando los riesgos, tanto para las personas como para el medio ambiente. También se exponen los resultados de varios experimentos, mediante los cuales se ha intentado conocer como se comportan las instalaciones y los materiales que las componen, frente a la agresión que producen los métodos biocidas. Y por último, se comparan los distintos tipos de instalaciones centralizadas de producción y almacenamiento de agua caliente y se estudian las ventajas e inconvenientes de cada una de ellas. Las propuestas que se formulan pretenden tres cosas y por este orden: controlar las poblaciones de legionela evitando que originen la enfermedad en las personas, proteger las instalaciones en las que puede desarrollarse la bacteria, y en la medida de lo posible, evitar da os al medio ambiente derivados del vertido de sustancias peligrosas. The author's extensive experience in the field of hospital maintenance engineer, has served as a basis to suggest alternatives to prevent the occurrence of Legionella neumophila bacteria in hazard installations. The intention with the recommendations proposed design, use and management of such facilities is to create in them hostile environments for microbial life and especially for legionella, combining physical and chemical methods. In this way we can decrease the bacteria populations, below the levels in light of current knowledge, are infective. Describes different options to traditional treatment methods, which can obtain the same results while minimizing risks for both people and the environment. It also presents the results of several experiments, by which an attempt to know how they behave facilities and materials that compose them, against the aggression that produce biocides methods. Finally, we compare the different types of centralized production and storage of hot wa
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