University of Havana
Recent publications
Background Tumor necrosis factor-alpha (TNFɑ) is a cytokine that manages the host defense mechanism, which may play a role in the pathogenesis of COVID-19 patients. Several single-nucleotide polymorphisms, described in the promoter region of the TNFα gene, have a significant role on its transcriptional activity. These include the − 308A > G polymorphism which increases the TNFα levels with the expression of the A allele. The aim of this study was to explore whether the TNFα.− 308A > G polymorphism affects the clinical state of COVID-19 patients. The study included a total of 1028 individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which were distributed in 3 groups: asymptomatic, mild symptomatic and severe symptomatic patients. The amplification-refractory mutation system was used to determine the genotype of the TNFα.− 308A > G polymorphism. Results Results show a higher tendency of being asymptomatic in individuals carrying the GG genotype (336 of 411; OR 1.24, 95% CI 0.91–1.70). The development of a severe form of SARS-CoV-2 infection was not found in subjects with the A allele compared to those with the G allele (OR 0.96, 95% CI 0.51–1.79), except in the eastern region of the country where the risk increased (OR 4.41, 95% CI 1.14–17.05). However, the subjects carrying the A allele had a higher chance of developing symptoms (OR 1.24, 95% CI 0.91–1.70) compared to those with the G allele. Conclusion The TNFα.− 308A allele has an influence on developing symptoms of COVID-19 in Cuban patients, and that it particularly increases the risk of presenting severe forms of the disease in the eastern region of the country.
In this work, we report on self-assembling of InxGa1-xN nanostructures under strong nitrogen-rich conditions on Si (111) substrates by molecular beam epitaxy. In-situ analysis of the reflection high-energy electron diffraction patterns allowed to follow the strain evolution of the films as well as to monitor the morphological changes related to the In incorporation. Scanning electron microscopy and atomic force microscopy images of the samples evidenced the growth of different nanostructures such as nanocolumns and nanowalls depending on the In content. X-ray diffraction (XRD) measurements allowed to determine the indium concentration while Rutherford backscattering spectrometry (RBS) was used to obtain the composition and thickness of the films and to explore the way in which In and Ga atoms are incorporated in the InxGa1-xN ternary alloy. XRD and RBS complementary analysis suggests that phase separation, occurring at the higher indium concentration, induces both the In and Ga rich phases segregation towards the external surface of the growths. Therefore, the columnar surface arrangement observed on the extreme binary compounds is transformed into separated nanowalls as the indium content increases. The probable origin of this morphology change is discussed. A shift towards lower energies of the low temperature photoluminescence spectra was observed for increased In concentration and a value of the bowing band gap parameter of about 3 was estimated using the extrema binary compounds and the intermediated indium concentration samples.
A local search method is developed and applied to create trajectories over S-box spaces in this work. These trajectories show a strong linear correlation between confusion coefficient variance, transparency order, modified transparency order, and revised transparency order under the Hamming weight model. When the confusion coefficient variance values increase, the values of transparency order, modified transparency order beta zero, and revised transparency order beta zero decrease, reflecting the same theoretical resistance against side-channel attacks by power consumption. From the best of our knowledge, it is the first time that Local Search trajectories are used to discover relations between cryptography properties. The experimental results and comparisons provide evidence of the capabilities of the proposal to handle the cryptography problems.
Colorectal cancer (CRC) is one of the most lethal cancers worldwide. If detected on time, surgery can expand life expectations of patients up to five more years. However, if metastasis has grown deliberately, the use of chemotherapy can play a crucial role in CRC control. Moreover, the lack of selectivity of current anticancer drugs, plus mutations that occur in cancerous cells, demands the development of new chemotherapeutic agents. Several steroids have shown their potentiality as anticancer agents, while some other compounds, such as Taxol and its derivatives bearing a carbamate functionality, have reached the market. In this article, the synthesis, characterization, and antiproliferative activity of four steroidal carbamates on mouse colon carcinoma CT26WT cells are described. Carbamate synthesis occurred via direct reaction between diosgenin, its B-ring modified derivative, and testosterone with phenyl isocyanate under a Brønsted acid catalysis. All obtained compounds were characterized by 1H and 13C Nuclear Magnetic Resonance (NMR), High Resolution Mass Spectroscopy (HRMS); their melting points are also reported. Results obtained from antiproliferative activity assays indicated that carbamates compounds have inhibitory effects on the growth of this colon cancer cell line. A molecular docking study carried out on Human Prostaglandin E Receptor (EP4) showed a high affinity between carbamates and protein, thus providing a valuable theoretical explanation of the in vitro results.
Herein we report the synthesis and characterization of a new copper(I) complex with triphenylphosphine (PPh3) and N‐(2‐thiophenecarbonyl)‐N’‐(3‐Cl, 4‐F‐phenyl)thiourea (HL), as ligands. The complex was characterized by vibrational (FTIR and FT‐Raman) and multinuclear (1H, 13C {1H}, 31P{1H}) NMR spectroscopies. The crystalline structure of the complex was determined by single‐crystal X‐ray diffraction, confirming that a neutral binuclear compound, identified as [Cu(PPh3)(L‐κ2‐N,μ‐S)]2, was obtained. The anionic thiourea ligand coordinates to the metal through the sulfur and nitrogen atoms in an unusual bidentate κ2‐N,μ‐S coordination mode. The complex is a dimer sited on a crystallographic center of symmetry. Each Cu2(μ‐S)2 cation bridges trough the sulfur atoms of two symmetry related thiourea moieties and is also coordinated to the nitrogen atom of the thiourea ligand and the phosphorus atom from PPh3 co‐ligand, forming a slightly distorted tetrahedral geometry. An intramolecular N−H⋅⋅⋅O=C hydrogen bond is observed in the anionic ligand, forming a six‐membered ring that stabilizes the N−H thioamide group. Hirshfeld surface analysis shows that the molecules are connected by weak intermolecular contacts C⋅⋅⋅C, H⋅⋅⋅C and H⋅⋅⋅H which add to the stability of the crystalline packing. The in vitro cytotoxicity study of the complex indicates that it is more active against human lung carcinoma cells (A549), when compared to the free ligand. A neutral binuclear copper(I) complex with acylthiourea and triphenylphosphine ligands is prepared. The anionic thiourea coordinates via a rather unusual bidentate κ2‐N,μ‐S coordination mode. Hirshfeld surface analysis shows that in the crystal the molecules are connected by weak intermolecular contacts. The complex is active against human lung carcinoma cells when compared to the free ligand.
The paper focuses on deriving the macroscale viscoelastic constitutive laws using asymptotic expansion method. Both the differential and integral form of the linear viscoelastic constitutive relation of the phases is used in deriving the effective incremental potential and effective constitutive relation, respectively. The integral form is handled by considering the correspondence principle and the Laplace–Carson (LC) transform. A closed-form expression for the effective viscoelastic properties in LC domain is obtained by means of the asymptotic homogenization method (AHM). In addition, AHM coupled with finite element simulation of a representative volume element with periodic boundary conditions is used (AHM + FE). The last step in both approaches is the numerical inversion to the time domain. Solution in time domain is obtained with numerical Laplace inversion algorithms. In case of the differential form, using variational approach, the effective incremental potential in time domain is directly obtained using mean-field method. Different homogenization approaches are exemplified for evaluation of the effective relaxation behavior of composite (viscoelastic matrix reinforced by unidirectional elastic fibers), and they are compared. In the approaches based on LC transform, effective modulus and Poisson’s ratio agree well with each other for any property contrast and fiber volume fraction. However, in case of relatively low property contrast, mean field overpredicts as compared to LC approaches in the fiber direction, whereas at relatively higher property contrast, it is vice versa. The difference increases at higher volume fractions due to synergistic effect of the error due to geometrical assumptions involved in the localization tensor and interaction effects of the fiber inclusions. A good agreement in all directions is observed among the three schemes at intermediate volume fractions and property contrast. This study serves as benchmark for further theoretical improvements and experimental investigations.
The replacement of the disulfide bridge by other types of side chain linkages has been a continuous endeavor in the development of cyclic peptide drugs with improved metabolic stability. Octreotide is a potent and selective somatostatin analog that has been used as an anticancer agent, in radiolabeled conjugates for the localization of tumors and as targeting moiety in peptide‐drug conjugates. Here, we describe an on‐resin methodology based on a multicomponent macrocyclization that enables the substitution of the disulfide bond by a tertiary lactam bridge functionalized with a variety of exocyclic moieties, including lipids, fluorophores, and charged groups. Conformational analysis in comparison with octreotide provides key information on the type of functionalization permitting the conformational mimicry with the bioactive peptide.
In this chapter, the Cuban educational experience is presented, based on the scientific investigation Approach to the characterization of the preschool Cuban child, carried out by the Latin American Reference Center for Preschool Education (CELEP) during the last two decades. The value of this investigation lies in knowing the characteristics of the first 6 years of life in order to implement quality education with a positive influence on the transition to primary school. The research emphasises results about socio-affective development, since teachers do not always consider this across both pedagogical and affective domains. The analysis is fundamentally qualitative, based on an extensive bibliographic search which illustrates Cuban reality. The results reflect the predominance of positive emotional states in both boys and girls. Play is still a fundamental activity, but it has to be well conducted in order to make children gradually ‘ready’ for ‘study activities’, that will be very important in the school stage. The chapter aims to provide valid information for teachers, pedagogues, psychologists, and professionals who are already trained or are in training, as well as families, in order to contribute to successful educational practices in the transition process.
Flexoelectric materials exhibit coupling between electric polarization and mechanical strain gradient. At the nano-scale and micro-scale, these materials offer a promising potential for the development of mechanical transducers and energy harvesters. This work proposes a new imperfect interface model simulating the behavior of a thin flexoelectric layer (adhesive) of vanishing thickness, embedded between two flexoelectric media (adherents). The adhesive is assumed to be mechanically compliant and electrically lowly-conducting. The interface model is obtained by using the asymptotic analysis. The contact laws, expressed in terms of the jumps and means values of the displacements, normal derivatives of the displacements, and electric potential across the interface, represent a formal generalization of the soft elastic and piezoelectric interface conditions. A simple application, considering a one-dimensional three-layer composite micro-bar subject to electro-mechanical loads, is developed in order to analytically/numerically assess the asymptotic model. Nonlocal phenomena and end-effects, related to a flexoelectric length-scale parameter, are highlighted. The example illustrates the usefulness of the proposed approach toward the design of thin nano- and microscale devices exploiting the flexoelectric effect.
EGFR signaling is an important regulator of SARS-CoV induced lung damage, inflammation and fibrosis. Nimotuzumab is a humanized anti-EGFR antibody registered for several cancer indications. An expanded access study was conducted to evaluate the safety and recovery rate of severe and critical patients with confirmed SARS-CoV-2 infection, treated with nimotuzumab in combination with the standard of care in the real-world scenario. The antibody was administered as an intravenous infusions every 72 h, up to 5 doses. In order to assess the impact of nimotuzumab, the recovery rate was compared with a paired retrospective cohort. Control patients received standard treatment according the national protocol but not nimotuzumab. Overall, 1,151 severe or critical patients received nimotuzumab in 21 hospitals of Cuba. Median age was 65 and 773 patients had at least one comorbidity. Nimotuzumab was very well-tolerated and mild or moderate adverse events were detected in 19 patients. 1,009 controls matching with the nimotuzumab patients, were selected using a “propensity score” method. The 14-day recovery rate of the nimotuzumab cohort was 72 vs. 42% in the control group. Controls had a higher mortality risk (RR 2.08, 95% CI: 1.79, 2.38) than the nimotuzumab treated patients. The attributable fraction was 0.52 (95% CI: 0.44%; 0.58), and indicates the proportion of deaths that were prevented with nimotuzumab. Our preliminary results suggest that nimotuzumab is a safe antibody that can reduce the mortality of severe and critical COVID-19 patients.
Background: In recent years, physical exercise has been investigated for its potential as a therapeutic tool in patients with end-stage renal disease (ESRD) undergoing hemodialysis maintenance treatment (HD). It has been shown that regular practice of moderate-intensity exercise can improve certain aspects of immune function and exert anti-inflammatory effects, having been associated with low levels of pro-inflammatory cytokines and high levels of anti-inflammatory cytokines. Purpose: The aim of this review is to examine the studies carried out in this population that analyzed the effect of intradialytic exercise on the inflammatory state and evaluate which exercise modality is most effective. Methods: The search was carried out in the MEDLINE, CINAHL Web of Science and Cochrane Central Register of Controlled Trials databases from inception to June 2022. The PEDro scale was used to assess methodological quality, and the Cochrane Risk of Bias Tool and MINORS were used to evaluate the risk of bias. The quality of evidence was assessed with GRADE scale. The outcome measures were systemic inflammation biomarkers. Results: Mixed results were found in terms of improving inflammation biomarkers, such as CRP, IL-6 or TNFα, after exercise. Aerobic exercise seems to improve systemic inflammation when performed at medium intensity while resistance training produced better outcomes when performed at high intensity. However, some studies reported no differences after exercise and these results should be taken with caution. Conclusions: The low quality of the evidence suggests that aerobic and resistance exercise during HD treatment improves systemic inflammation biomarkers in patients with ESRD. In any case, interventions that increase physical activity in patients with ESRD are of vital importance as sedentary behaviors are associated with mortality. More studies are needed to affirm solid conclusions and to make intervention parameters, such as modality, dose, intensity or duration, sufficiently clear. Keywords: chronic kidney disease; hemodialysis; inflammation; exercise
Do ecomorphological differences predict the co–existence of cave bats in Cuba? Identifying mechanisms that influence the coexistence of species is primordial to understanding patterns and processes in biodiversity. Here we aimed to assess the association between coexistence and morphology of cave bats in Cuba and differences in morphologic and dietary aspects. We assembled lists of species from 108 localities with at least three co–inhabiting species. Fourteen species of bats in at least three localities were included. Based on the literature we also obtained the mean values of five morphological variables and the basic composition of diet. We calculated coexistence patterns using EcoSim v7.72 based on the average number of checkerboard units that appeared between each pair of species. We evaluated the predictive capacity of the morphological variables and diet over the degree of coexistence between species using a neural regression network. The best neural network was accepted (correlation of 0.87, training error < 0.006). The prediction error was 13.5 % (± 1.1) of the value of the coexistence index. Our findings indicate that the composition of cave bat assemblages in Cuba has not come about by chance. Rather, we found that the most functionally different species tended to coexist. This finding is consistent with the effect of competitive relationships driving the composition of species of cave bats in Cuba.
Earth construction is a revisited topic due to the low-cost self-production employed in communities and locations where conventional materials (concrete and steel) are not available. One of the properties popularly recognized for earth-based buildings is the pleasant indoor thermal sensation. This article presents the development of a model to characterize the indoor air temperature applied to adobe houses in San Carlos, Tamaulipas, Mexico. The model is developed from the heat transfer equations in an ideal case where the temperature is modified by conduction through the wall, and the interior air is heated by convection. In the ideal case, it is considered that there are no doors or windows open because it is what commonly occurs in earth-based houses during the warmest period of the year. It was found that for a thickness greater than 10 cm there is no significant increase in temperature assuming an outside temperature above 40 °C and an initial indoor temperature of 25 °C. The model characterizes and predicts a strong relationship between the physical properties of the air and the wall, the thickness of the wall, the dimensions and shape of the room, and the roughness of the outer wall. This consideration makes it possible to quantitatively estimate comfortability based on indoor temperature and wall thickness, which is an expected behavior according to the literature. This is important because not only has an impact on the construction of new buildings but also on the critical maintenance of existing houses.
We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to developmental asynchrony and unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.
The industrial production of plants promoter like auxins is gaining interest, in consequence it is important to un- derstand the metabolism of the microorganisms involved and the optimal conditions for their industrial production. In this study the metabolic model of Bacillus subtilis was used to estimate intracellular fluxes and the robustness of the principal branching points of aerobic propionate metabolism for the 3-indoleacetic acid (IAA) production. The robustness analyzes of the metabolic network showed the enzymes that participate in the synthesis of erythrose 4-phosphate and glyceraldehyde 3-phosphate as possible limiting metabolites in the synthesis of IAA and might be a target for metabolic engineering strategies. The phenotype phase plane analysis allowed the identification of the opti- mal rate growth conditions to produce the auxin (less than 0.1 h ).
Drought severely affects soybean productivity, challenging breeding/management strategies to increase crop resilience. Hormone-based biostimulants like brassinosteroids (BRs) modulate growth/defence trade-off, mitigating yield losses; yet, natural molecule's low stability challenges the development of cost-effective and long-lasting analogues. Here, we investigated for the first time the effects of BR functional analogue DI-31 in soybean physiology under drought by assessing changes in growth, photosynthesis, water relations, antioxidant metabolism, nodulation, and nitrogen homeostasis. Moreover, DI-31 application frequencies' effects on crop cycle and commercial cultivar yield stabilisation under drought were assessed. A single foliar application of DI-31 favoured plant drought tolerance, preventing reductions in canopy development and enhancing plant performance and water use since the early stages of stress. The analogue also increased the antioxidant response, favouring nitrogen homeostasis maintenance and attenuating the nodular senescence. Moreover, foliar applications of DI-31 every 21 days enhanced the absolute yield by ~ 9% and reduced drought-induced yield losses by ~ 7% in four commercial cultivars, increasing their drought tolerance efficiency by ~ 12%. These findings demonstrated the practical value of DI-31 as an environmentally friendly alternative for integrative soybean resilience management under drought.
El artículo analiza el discurso fundamentalista religioso cubano sobre el matrimonio igualitario y la educación sexual integral, durante mayo y junio de 2021, en un corpus formado por cuatro declara­ciones de iglesias. Partiendo del análisis semántico del discurso y del análisis del discurso ideológico, se realiza un estudio en dos momentos: primero, un análisis cuantitativo lexicométrico; y luego, un análisis cualitativo, centrado en la identificación y descripción de cuatro representaciones discursivas. Durante el análisis, se vinculan también, cuando corresponde, las estructuras discursivas e ideológi­cas. Los resultados muestran que se trata de un discurso construido sobre oposiciones antagónicas, que reduce el campo discursivo a dos posicionamientos enfrentados. Los emisores se presentan como víctimas, como (representantes de una) mayoría y como autoridad moral y racional; y construyen a su Otro ideológico como victimarios y como una minoría inmoral e irracional no representativa. Es un discurso connotativo, que busca persuadir por medio de emociones, aunque incorpora también llamados a la racionalidad. Se presenta como heredero y defensor de la historia e identidad nacio­nales, y sugiere una organización jerárquica de la ideología fundamentalista religiosa, donde tiene prioridad la hegemonía cultural.
The dynamics of gases made of particles interacting dissipatively {known as granular gases{ can be fully described by the translational and rotational motion of the individual particles; however, most of the results in the field refer to the limit of smooth particles, which implies that the rotational degrees of freedom are suppressed. Here we investigate the opposite limit: we consider a granular gas where the translational degrees of freedom are suppressed, and the key degrees of freedom are rotational. Our results indicate that for many-particle systems of pure rotators collective effects almost completely suppressed. This is in a sharp contrast to granular gases of smooth particles and other conventional matter where the translational degrees of freedom dominate the kinetics.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
2,409 members
Eduardo Ortega
  • Laboratorio de Fisiología Vegetal, Departamento de Biología Vegetal
Annia Hernández - Rodríguez
  • Facultad de Biología
Estael Ochoa
  • Departamento de Química Orgánica
Octavio Calzadilla
  • Departamento de Física General
Olimpia Carrillo Farnés
  • Departamento de Bioquímica
Information
Address
San Lázaro y L, 10400, Havana, Cuba
Head of institution
Dra. Miriam Nicado García
Website
http://www.uh.cu