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Introduction: Natural products are an option to be used in different conditions in the oral cavity, such as Camellia sinensis, which due to its different properties would be beneficial in the erosion of the dental surface. Objetive: Determinar el efecto del extracto de Camellia sinensis (C. sinensis) adicionado con flúor frente a la acción erosiva de ácidos no bacterianos en la superficie de la dentina humana. Materials and Methods: Quasi-experimental, prospective, longitudinal, and in vitro study, consisting of 50 samples of human dentin, which were classified into 5 study groups: distilled water, hydrochloric acid, 2% C. sinensis extract, sodium fluoride. 2% and 2% C. sinensis extract added with 2% sodium fluoride. The surface roughness of each sample was evaluated with the SRT6200 digital roughness meter, obtaining a total average roughness and the measurements were carried out in two moments. Results: It was observed that the 2% C. sinensis extract, the 2% sodium fluoride, and the C. sinensis extract added with 2% sodium fluoride, showed a variation in surface roughness between before and after, which was not significant (p<0.05) in all cases. It should be noted that the C. sinensis plus sodium fluoride group is the one that obtained the best variation in the mean surface roughness than the other groups studied. Conclusions: The 2% C. sinensis extract, 2% sodium fluoride, and the combination of both compounds demonstrated an inhibitory effect against the erosive action of hydrochloric acid (0.01 M) on the dentin surface, not presenting a statistically significant difference in the results.

Introducción: Los productos naturales son una opción para ser usados en diferentes afecciones en la cavidad bucal, como lo podría ser la Camellia sinensis, que por sus diferentes propiedades sería de beneficio en la erosión de la superficie dental. Objetivo: Determinar el efecto del extracto de Camellia sinensis (C. sinensis) adicionado con flúor frente a la acción erosiva de ácidos no bacterianos en la superficie de la dentina humana. Materiales y Métodos: Estudio cuasi experimental, prospectivo, longitudinal ein vitro, constituido por 50 muestras de dentina de dientes permanentes, que se clasificaron en 5 grupos de estudio: Agua destilada, ácido clorhídrico, extracto de C. sinensis a 2%, fluoruro de sodio al 2% y extracto de C. sinensisa 2% adicionado con fluoruro de sodio al 2%. Se evaluó la rugosidad superficial de cada muestra con el rugosímetro digital SRT6200, obteniéndose una rugosidad media total y se realizaron las mediciones en dos momentos. Resultado: Se observó que el extracto de C. sinensisal 2%, el fluoruro de sodio al 2% y el extracto de C. sinensis adicionado con fluoruro de sodio al 2%, presentaron una variación de la rugosidad superficial entre el antes y el después, no siendo esta significativa (p<0.05) en todos los casos. Cabe resaltar que el grupo C. sinensis más fluoruro de sodio, es el que obtuvo una mejor variación de la media de rugosidad superficial, que los otros grupos estudiados. Conclusión: El extracto de C. sinensisal 2%, el fluoruro de sodio al 2% y la combinación de ambos compuestos demostraron un efecto inhibitorio frente a la acción erosiva del ácido clorhídrico (0,01 M) en la superficie de dentina, no presentando una diferencia estadísticamente significativa en los resultados.

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Introducción: La ferroptosis es un proceso no apoptótico de muerte celular regulada que depende de la presencia de iones hierro en el medio intracelular. Se caracterizada por la acumulación de especies reactivas de lípidos oxidados y radicales libres en las membranas celulares. Los inductores e inhibidores de este proceso inciden de manera circunstancial en él, con cuya respuesta celular se trabaja en función de elaborar modelos para el tratamiento del cáncer. Objetivo: Profundizar en el proceso de ferroptosis con un enfoque hacia los inductores e inhibidores, el establecimiento de modelos biofisicoquímicos y las estrategias terapéuticas para el tratamiento del cáncer. Métodos: Se realizó una revisión de los estudios más significativos sobre el tema, publicados en la Web of Science, PubMed, EBSCO, y Scopus. Resultados: Gracias al novedoso descubrimiento de la ferroptosis como impulsor de la muerte de células tumorales para tratar el cáncer, se han comenzado a desarrollar modelos teóricos que simulan el comportamiento de estas células y la complejidad en sistemas biológicos; que permiten encontrar procedimientos alternativos y menos invasivos contra esta y otras enfermedades. Conclusiones: Los inductores e inhibidores tienen una función primordial a la hora de predecir la influencia en la sensibilidad a la ferroptosis; por lo que se indagó en los mecanismos de funcionamiento de estos, que facilitará la forma de inducir en mayor o menor grado la muerte celular y disminuir la población de células cancerígenas(AU)

Introduction: Ferroptosis is a non-apoptotic process of regulated cell death that depends on the presence of iron ions in the intracellular medium. It is characterized by the accumulation of reactive species of oxidized lipids and free radicals in cell membranes. The inducers and inhibitors of this process circumstantially affect it, whose cellular response is used to develop models for cancer treatment. Objective: To deepen the ferroptosis process focusing on inducers and inhibitors, the establishment of biophysiochemical models and therapeutic strategies for cancer treatment. Methods: A review was carried out of the most significant studies on the subject, published in the Web of Science, PubMed, EBSCO and Scopus. Results: Thanks to the novel discovery of ferroptosis as a conductor of tumor cell death to treat cancer, theoretical models have begun to be developed that simulate the behavior of these cells and the complexity in biological systems; that allow finding alternative and less invasive procedures against this and other diseases. Conclusions: Inductors and inhibitors have a primary role in predicting the influence on sensitivity to ferroptosis; therefore, the mechanisms of operation of these were investigated, which will facilitate the way to induce cell death to a greater or lesser degree and reduce the population of cancer cells(AU)

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Introduction: The tea plant, Camellia sinensis, is one of the most popular non-alcoholic beverages in the world. The main components of Camellia sinensis include amino acids, fatty acids, phenolic compounds, flavins and purine alkaloids (xanthines). For this reason, in the field of medicine, Camellia sinensis has been used as an anticancer, anxiolytic, antidiabetic, antiobesity, anti-inflammatory, analgesic, antipyretic, chemopreventive, cytotoxic and apoptogenic, genoprotective, hepatoprotective, nephroprotective, hemato-protective, and in wound healing, among other uses. Objective: To carry out a systematic review of the use of C. sinensis as supportive therapy in the treatment of oral disorders. Materials and Methods: This systematic review was carried out following the PRISMA guidelines. The search was carried out in the PubMed, ScienceDirect and Google Academic databases. Articles from studies of Camellia sinensis were reviewed and those from a secondary source, such as literature review articles, were excluded Results: A total of 12 full-text articles were selected for review, in which the properties of Camellia sinensis are detailed. Conclusions: According to the bibliography reviewed, C. sinensis exhibits anticariogenic properties, applications in the treatment of dental erosion, applications in the treatment of gingivitis and bacterial plaque, and applications in the prevention of oral cancer; however, more controlled clinical trials are needed to confirm its effectiveness and safety of use.

Introducción: La planta del té es una de las bebidas no alcohólicas más populares en todo el mundo. Entre los principales componentes de Camellia sinensis tenemos los aminoácidos, ácidos grasos, compuestos fenólicos, flavinas y alcaloides de purina (xantinas). Por ello en medicina, la Camellia sinensis se ha utilizado como anticancerígeno, ansiolítico, antidiabético, antiobesidad, antiinflamatorio, analgésico, antipirético, quimiopreventivo, citotóxico y apoptógeno, genoprotector, hepatoprotector, nefroprotector, hematoprotector, cicatrizantes de heridas, entre otros. Objetivo: Realizar una revisión sistemática del uso de C. sinensis como apoyo en el tratamiento de afecciones bucales. Materiales y Métodos: Esta revisión sistemática se llevó a cabo siguiendo los lineamientos PRISMA. La búsqueda se realizó en las bases de datos PubMed, Science Direct y Google Academic. Se revisaron los artículos de estudios de Camellia sinensis y se excluyeron aquellos de fuente secundaria, como los de revisión de la literatura. Resultados: Se seleccionaron un total de 12 artículos de texto completo para la revisión. En los que se detalla las propiedades de la Camellia sinensis. Conclusión: De acuerdo a la bibliografía revisada, la C. sinensis exhibió efecto anticariogénico, aplicación en el tratamiento de la erosión dental, aplicación en el tratamiento de gingivitis y placa bacteriana, y aplicación en la prevención del cáncer bucal, sin embargo, se necesitan realizar más ensayos clínicos controlados que confirmen su efectividad y seguridad de uso.

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In this work we introduce a simple mathematical model, based on master equations, to describe the time evolution of the popularity of hashtags on the Twitter social network. Specifically, we model the total number of times a certain hashtag appears on user's timelines as a function of time. Our model considers two kinds of components: those that are internal to the network (degree distribution) as well as external factors, such as the external popularity of the hashtag. From the master equation, we are able to obtain explicit solutions for the mean and variance and construct confidence regions. We propose a gamma kernel function to model the hashtag popularity, which is quite simple and yields reasonable results. We validate the plausibility of the model by contrasting it with actual Twitter data obtained through the public API. Our findings confirm that relatively simple semi-deterministic models are able to capture the essentials of this very complex phenomenon for a wide variety of cases. The model we present distinguishes from other existing models in its focus on the time evolution of the total number of times a particular hashtag has been seen by Twitter users and the consideration of both internal and external components.

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Introducción: La metástasis del cáncer es la transferencia de células tumorales de un órgano a otro mediante una serie de multipasos secuenciales interrelacionados. Este proceso es uno de los principales retos en el tratamiento del cáncer debido a su heterogeneidad biológica. El proceso de metástasis es considerado la principal causa de muerte en esta enfermedad, reportándose que más de 90 por ciento de las muertes por cáncer son debidos a esta etapa. Objetivo: Actualizar los conocimientos sobre metástasis en tumores sólidos y su asociación con transición epitelial-mesenquimal (EMT) en relación a la evolución y emergencia del cáncer. Método: Se realizó una revisión, no sistemática, de los estudios más significativos sobre el tema, publicados en la Web of Science, Pubmed, Ebsco, Scopus e Infomed. Conclusiones: La metástasis es la principal causa de muerte del cáncer, por lo que entender las bases del mecanismo de la formación de tumores metastásicos permitirá realizar terapias más eficaces para tratar el cáncer(AU)

Introduction: Cancer metastasis is the transfer of tumor cells from one organ to another through a series of interrelated sequential multi-steps. This process is one of the main challenges in cancer treatment due to the biological heterogeneity. The metastasis process is considered the main cause of death in this disease, accounting for more than 90 percent of cancer deaths. Objective: To identify the most recent advances on solid tumor metastasis and the association with epithelial-mesenchymal transition (EMT) in relation to the evolution and emergence of cancer. Method: A non-systematic review was carried out of the most significant studies on the subject, published in Web of Science, Pubmed, Ebsco, Scopus and Infomed. Conclusions: Metastasis is the main cause of cancer death, so understanding the bases of the mechanism for metastatic tumor formation will allow for more effective therapies(AU)

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The calculation of absolute binding affinities for protein-inhibitor complexes remains as one of the main challenges in computational structure-based ligand design. The present work explored the calculations of surface fractal dimension (as a measure of surface roughness) and the relationship with experimental binding free energies of Plasmepsin II complexes. Plasmepsin II is an attractive target for novel therapeutic compounds to treat malaria. However, the structural flexibility of this enzyme is a drawback when searching for specific inhibitors. Concerning that, we performed separate explicitly solvated molecular dynamics simulations using the available high-resolution crystal structures of different Plasmepsin II complexes. Molecular dynamics simulations allowed a better approximation to systems dynamics and, therefore, a more reliable estimation of surface roughness. This constitutes a novel approximation in order to obtain more realistic values of fractal dimension, because previous works considered only x-ray structures. Binding site fractal dimension was calculated considering the ensemble of structures generated at different simulation times. A linear relationship between binding site fractal dimension and experimental binding free energies of the complexes was observed within 20 ns. Previous studies of the subject did not uncover this relationship. Regression model, coined FD model, was built to estimate binding free energies from binding site fractal dimension values. Leave-one-out cross-validation showed that our model reproduced accurately the absolute binding free energies for our training set (R2  = 0.76; <|error|> =0.55 kcal/mol; SDerror  = 0.19 kcal/mol). The fact that such a simple model may be applied raises some questions that are addressed in the article.

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The thermodynamical formalism of irreversible processes offers a theoretical framework appropriate to explain the complexity observed at the macroscopic level of dynamic systems. In this context, together with the theory of complex systems and systems biology, the thermodynamical formalism establishes an appropriate conceptual framework to address the study of biological systems, in particular cancer.The Chapter is organized as follows: In Subheading 1, an integrative view of these disciplines is offered, for the characterization of the emergence and evolution of cancer, seen as a self-organized dynamic system far from the thermodynamic equilibrium. Development of a thermodynamic framework, based on the entropy production rate, is presented in Subheading 2. Subheading 3 is dedicated to all tumor growth, as seen through a "phase transitions" far from equilibrium. Subheading 4 is devoted to complexity of cancer glycolysis. Finally, some concluding remarks are presented in Subheading 5.

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We examine the relationship between exponential correlation functions and Markov models in a bacterial genome in detail. Despite the well known fact that Markov models generate sequences with correlation function that decays exponentially, simply constructed Markov models based on nearest-neighbor dimer (first-order), trimer (second-order), up to hexamer (fifth-order), and treating the DNA sequence as being homogeneous all fail to predict the value of exponential decay rate. Even reading-frame-specific Markov models (both first- and fifth-order) could not explain the fact that the exponential decay is very slow. Starting with the in-phase coding-DNA-sequence (CDS), we investigated correlation within a fixed-codon-position subsequence, and in artificially constructed sequences by packing CDSs with out-of-phase spacers, as well as altering CDS length distribution by imposing an upper limit. From these targeted analyses, we conclude that the correlation in the bacterial genomic sequence is mainly due to a mixing of heterogeneous statistics at different codon positions, and the decay of correlation is due to the possible out-of-phase between neighboring CDSs. There are also small contributions to the correlation from bases at the same codon position, as well as by non-coding sequences. These show that the seemingly simple exponential correlation functions in bacterial genome hide a complexity in correlation structure which is not suitable for a modeling by Markov chain in a homogeneous sequence. Other results include: use of the (absolute value) second largest eigenvalue to represent the 16 correlation functions and the prediction of a 10-11 base periodicity from the hexamer frequencies.

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Searching for generic behaviors has been one of the driving forces leading to a deep understanding and classification of diverse phenomena. Usually a starting point is the development of a phenomenology based on observations. Such is the case for power law distributions encountered in a wealth of situations coming from physics, geophysics, biology, lexicography as well as social and financial networks. This finding is however restricted to a range of values outside of which finite size corrections are often invoked. Here we uncover a universal behavior of the way in which elements of a system are distributed according to their rank with respect to a given property, valid for the full range of values, regardless of whether or not a power law has previously been suggested. We propose a two parameter functional form for these rank-ordered distributions that gives excellent fits to an impressive amount of very diverse phenomena, coming from the arts, social and natural sciences. It is a discrete version of a generalized beta distribution, given by f(r) = A(N+1-r)(b)/r(a), where r is the rank, N its maximum value, A the normalization constant and (a, b) two fitting exponents. Prompted by our genetic sequence observations we present a growth probabilistic model incorporating mutation-duplication features that generates data complying with this distribution. The competition between permanence and change appears to be a relevant, though not necessary feature. Additionally, our observations mainly of social phenomena suggest that a multifactorial quality resulting from the convergence of several heterogeneous underlying processes is an important feature. We also explore the significance of the distribution parameters and their classifying potential. The ubiquity of our findings suggests that there must be a fundamental underlying explanation, most probably of a statistical nature, such as an appropriate central limit theorem formulation.

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We report here the use of the mutual information theory for the certification of annotated rice coding sequences of both GenBank and TIGR databases. Considering coding sequences larger than 600 bp, we successfully screened out genes with aberrant compositional features. We found that they represent about 10% of both datasets after cleaning for gene redundancy. Most of the rejected accessions showed a different trend in GC3% vs GC2% plot compared to the set of accessions that have been published in international journals. This suggests the existence of a bias in the pattern recognition algorithms used by gene prediction programs.

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Con el objetivo de identificar factores anatómicos vinculables a las variables significaciones hemodinámica y clínica de las venas comunicantes incompetentes de la pierna, se estudiaron mediante disección cadavérica, un total de100 miembros inferiores. En el 91 por ciento se hallo una comunicante principal, que presentaba patrones de anastomosis variables entre los colectores superficiales y el sistema profundo , y que recibía en un 12 por ciento de los casos, gruesas colaterales musculares subfasciales. En caso de incompetencia valvular, es probable que estas variaciones anatómicas puedan incidir en la transmisión y magnitud del reflujo, debiendo determinarse susignificación en estudios clínicos

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