Effect of 6-thioguanine on the stability of duplex DNA

The incorporation of 6-thioguanine (S6G) into DNA is a prerequisite for its cytotoxic action, but duplex structure is not significantly perturbed by the presence of the lesion [J. Bohon and C. R. de los Santos (2003) Nucleic Acids Res., 31, 1331–1338]. It is therefore possible that the mechanism of cytotoxicity relies on a loss of stability rather than a pathway involving direct structural recognition. The research described here focuses on the changes in thermodynamic properties of duplex DNA owing to the introduction of S6G as well as the kinetic properties of base pairs involving S6G. Replacement of a guanine in a G•C pair by S6G results in ∼1 kcal/mol less favorable Gibbs free energy of duplex formation at 37°C. S6G•T and G•T mismatch-containing duplexes have almost identical Gibbs free energy at 37°C, with values ∼3 kcal/mol less favorable than that of the control. Base pair stability is affected by S6G. The lifetime of the normal G•C base pair is ∼125 ms, whereas that of the G•T mismatch is below the detection limit. The lifetimes of S6G•C and S6G•T pairs are ∼7 and 2 ms, respectively, demonstrating that, although S6G significantly decreases the stability of the pairing with cytosine, it slightly increases that of a mismatch

Angiotensin-(1-7) increases osmotic water permeability in isolated toad skin

Angiotensin-(1-7) (Ang-(1-7)) increased osmotic water permeability in the isolated toad skin, a tissue with functional properties similar to those of the distal mammalian nephron. Concentrations of 0.1 to 10 μM were effective, with a peak at 20 min. This effect was similar in magnitude to that of frog skin angiotensin II (Ang II) and oxytocin but lower than that of human Ang II and arginine-vasotocin. The AT2 angiotensin receptor antagonist PD 123319 (1.0 μM) fully inhibited the response to 0.1 μM Ang-(1-7) but had no effect on the response to Ang II at the same concentration. The specific receptor antagonist of Ang-(1-7), A-779, was ineffective in blocking the response to Ang-(1-7) and to frog skin Ang II. The AT1 receptor subtype antagonist losartan, which blocked the response to frog skin Ang II, was ineffective in blocking the response to Ang-(1-7). The present results support the view of an antidiuretic action of Ang-(1-7) in the mammalian nephron.Fil: Santos, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Jerez, Susana Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Peral, Maria de Los Angeles. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Coviello, Alfredo. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Incorporation of 3-Aminobenzanthrone into 2′-Deoxyoligonucleotides and Its Impact on Duplex Stability

3-Nitrobenzanthrone (3NBA), an environmental pollutant and potent mutagen, causes DNA damage via the reaction of its metabolically activated form with the exocyclic amino groups of purines and the C-8 position of guanine. The present work describes a synthetic approach to the preparation of oligomeric 2′-deoxyribonucleotides containing a 2-(2′-deoxyguanosin-N2-yl)-3-aminobenzanthrone moiety, one of the major DNA adducts found in tissues of living organisms exposed to 3NBA. The NMR spectra indicate that the damaged oligodeoxyribonucleotide is capable of forming a regular double helical structure with the polyaromatic moiety assuming a single conformation at room temperature; the spectra suggest that the 3ABA moiety resides in the duplex minor groove pointing toward the 5′-end of the modified strand. Thermodynamic studies show that the dG(N2)-3ABA lesion has a stabilizing effect on the damaged duplex, a fact that correlates well with the long persistence of this damage in living organisms

Water renewal mechanisms of the Bay of Algeciras in the Strait of Gibraltar

The Bay of Algeciras (BA) is a marine environment subject to high levels of anthropogenic pressure. Here we analyze observations collected at the Bay and the results of an ocean circulation model to investigate its circulation and variability. Special attention is paid to the identification of the mechanisms enhancing the exchange of water with the adjacent Strait of Gibraltar and therefore contributing to maintain satisfactory levels of water quality.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Childhood T-cell acute lymphoblastic leukemia in a single Latin American center: impact of improved treatment scheme and support therapy on survival

Background and objective: T-cell acute lymphoblastic leukemia (T-ALL) in children representsa high-risk disease. There is a lack of studies assessing the outcome of T-ALL in Hispanicpopulations, in which it is a rare malignancy. We report the characteristics and results oftreatment for childhood T-cell ALL in children over 14 years at a Latin American referencecenter.Material and methods: From January 2005 to December 2018, there occurred the analysisof twenty patients ≤ 16 years of age from a low-income open population diagnosed ata university hospital in Northeast Mexico. Clinical and laboratory characteristics, treat-ment regimens and outcomes were assessed by scrutinizing clinical records and electronicdatabases. Diagnosis was confirmed by flow cytometry, including positivity for CD-2, 5, 7and surface/cytoplasmic CD3. Survival rates were assessed by the Kaplan-Meier method.Results: There was a male preponderance (70 %), with a 2.3 male-to-female ratio (p = .074), themedian age being 9.5 years. Leucocytes at diagnosis were ≥ 50 × 109/L in 13 (65 %) children,with CNS infiltration in 6 (30 %) and organomegaly in 10 (50 %). The five-year overall survival(OS) was 44.3 % (95 % CI 41.96–46.62), significantly lower in girls, at 20.8 % (95 % CI 17.32–24.51)vs. 53.1 % (95 % CI 50.30–55.82), (p = .035) in boys; there was no sex difference in the event-freesurvival (EFS) (p = .215). The survival was significantly higher after 2010 (p = .034).Conclusion: The T-cell ALL was more frequent in boys, had a higher mortality in girls and thesurvival has increased over the last decade with improved chemotherapy and supportivecare

Simetrías potenciales de un modelo matemático que describe las vibraciones de una viga

En este trabajo presentamos un estudio, desde el punto de vista de la teoría de las simetrías potenciales clásicas y no clásicas para ecuaciones en derivadas parciales, del modelo que describe las vibraciones de una viga

Machine learning model through ensemble bagged trees in predictive analysis of university teaching performance

The objective of this study is to analyze and discuss the metrics of the Machine Learning model through the Ensemble Bagged Trees algorithm, which will be applied to data on satisfaction with teaching performance in the virtual environment. Initially the classification analysis through the Matlab R2021a software, identified an Accuracy of 81.3%, for the Ensemble Bagged Trees algorithm. When performing the validation of the collected data, and proceeding with the obtaining of the predictive model, for the 4 classes (satisfaction levels), total precision values of 82.21%, Sensitivity of 73.40%, Specificity of 91.02% and of 90.63% Accuracy. In turn, the highest level of the area under the curve (AUC) by means of the Receiver operating characteristic (ROC) is 0.93, thus considering a sensitivity of the predictive model of 93%. The validation of these results will allow the directors of the higher institution to have a database, to be used in the process of improving the quality of the educational service in relation to teaching performance.Campus Lima Nort

Desarrollo de una metodología para la zonificación de Haití en función del riesgo potencial frente a brotes de cólera

Este trabajo pretende proyectar los diferentes contagios de cólera en Haití. Cólera es una de las grandes epidemias más graves a nivel mundial capaz de provocar gran cantidad de mortalidad en una población que no esté preparada para enfrentarla, ya sea previniéndola o tratando la enfermedad. La amplia experiencia con el cólera ha demostrado que es imposible evitar su introducción en un país, pero si puede evitarse mediante medidas de control apropiadas

Revisión de la implementación del machine learning en la seguridad de la información

La presente revisión tiene como objetivo dar a conocer cómo se está implementando el machine learning en la seguridad de la información. Por tal motivo se optó por la metodología PRISMA para identificar artículos en diferentes bases de datos en los últimos 5 años. Se utilizó las siguientes bases de datos: Scopus, Science Direct, Research Gate y Google Académico. Posteriormente se aplicaron los criterios de inclusión y exclusión, dando un resultado de 16 artículos donde se implementa el machine learning en la seguridad de la información para dar respuesta a las preguntas planteadas. En conclusión, las diversas técnicas y/o algoritmos del machine learning aplicados en la seguridad de la información es una necesidad de las organizaciones en la actualidad para la protección de la información, siendo unos de los algoritmos más usados las Redes Neuronales Artificiales (ANN) y el área donde mayormente se implementa el machine learning para la seguridad de la información es Internet de las cosas (IoT)

Changes in the protein profile of Habanero pepper (Capsicum chinense J.) somatic embryos during development

Protein profile was studied during the development of Capsicum chinense somatic embryos. The total protein content and profile of polypeptides (by sodium dodecyl sulfate polyacrylamide gel electrophoresis) of somatic embryos at different developmental stages (globular, heart-shaped, torpedo and cotyledonary stages) were analyzed. The protein profile of zygotic embryos included nine exclusive bands with molecular weights of 4.0, 5.2, 8.1, 13.7, 20.9, 23.7, 41, 50 and 69.3 kDa; these bands were not observed in the protein profile of somatic embryos. Coincidently, five of these bands possessed similar molecular weights to those reported for storage proteins in other plant species. Protein content showed a clear decreasing tendency with increasing somatic embryo development. The lowest protein content was detected in somatic embryos at the cotyledonary stage (0.436 µg/mg fresh weight), and the highest content was found in somatic embryos at the globular stage (2.98 µg/mg fresh weight). Total proteins two-dimensional electrophoresis (2-DE) analysis of mature zygotic embryo (prior to the desiccation) and cotyledonal somatic embryo, showed significant differences in the protein profile of both types of embryos. Zygotic embryo showed the proteins expression of isoelectric point between 4 to 7 and 7 to 10, and molecular weights between 25 to 36 KDa, which were not expressed in the cotyledonal somatic embryo. The low protein content during the development of the somatic embryos, particularly at the cotyledonary stage, is a factor that could be related with the low rate of conversion to plantlets and the high frequency of deformed somatic embryos of C. chinense.Key words: Recalcitrance, maturation, germination, conversion