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Central America is home to one of the most abundant herpetofauna in the Americas, occupying only 7% of the continent's total area. Vipers and lizards are among the most relevant venomous animals in medical practice due to the consequences of envenomation from the bite of these animals. A great diversity of biomolecules with immense therapeutic and biotechnological value is contained in their venom. This paper describes the prominent leading representatives of the family Viperidae, emphasizing their morphology, distribution, habitat, feeding, and venom composition, as well as the biotechnological application of some isolated components from the venom of the animals from these families, focusing on molecules with potential anti-thrombotic action. We present the leading protein families that interfere with blood clotting, platelet activity, or the endothelium pro-thrombotic profile. In conclusion, Central America is an endemic region of venomous animals that can provide many molecules for biotechnological applications.

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Objective: The study objective was to evaluate the safety and clinical and echocardiographic outcomes of a new surgical technique in adult patients diagnosed with a giant left atrium. Methods: We analyzed a cohort of patients who underwent left atrium reduction surgery between January 2016 and June 2020 performed by a specialized surgical team in 2 national reference centers in Lima, Peru. We assessed the major adverse valvular-related events and the New York Heart Association functional class as primary clinical outcomes. Also, our primary echocardiographic endings were the diameter, area, and volume of the left atrium. We assessed these variables at 3 time periods: baseline (t0), perioperative period (t1), and extended follow-up (t2: 12 ± 3.4 months). We carried out descriptive and bivariate exploratory statistical analysis for dependent measures. Results: We included 17 patients, 70.6% of whom were women. Rheumatic mitral valve disease (76.5%) was the main etiology. We performed 14 (82.4%) mitral valve replacements and 3 repairs. Major adverse valvular-related events occurred in 1 patient (5.9%) (hemorrhagic stroke) at t1. A significant reduction in the size of the left atrium was observed: diameter (77 mm vs 48 mm, P < .001), area (75 cm2 vs 31 cm2, P < .001), and volume (332 cm3 vs 90 cm3, P < .001). Compared with t0 and t1, these echocardiographic findings remained without significant changes during t2. Conclusions: Our surgical left atrium reduction technique was associated with improved clinical functionality and reduced left atrium measures in patients with a giant left atrium undergoing mitral valve surgery.

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The performance of Candida antarctica lipase B (CALB) has been evaluated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4)/water mixtures in a wide range of molar fractions (χBMIMBF4) with and without 1-dodecyl-3-methylimidazolium tetrafluoroborate (C12-MIMBF4), a surfactant derived from BMIMBF4. The main aim of this work is to evaluate the influence of χBMIMBF4 over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate p-nitrophenyl laureate in each χBMIMBF4. The kinetic study for χBMIMBF4 at around 0.2 proved to be a border point in enzymatic activity. At χBMIMBF4 = 0.1, the lipase activity increases in the presence of C12-MIMBF4. However, at higher concentrations, BMIMBF4 has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF4 molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF4 acts directly on the changes induced on the enzyme upon its interaction with the micellar interface. This study opens a green perspective toward the biocatalysis field.

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The photoinduced degradation of the azo dye Disperse Red 1 was studied in a microheterogeneous system comprising titanium oxide (TiO2 ) and sodium dodecyl sulfate, exposed to UV light. Degussa P25, Anatase and TiO2 synthesized in acidic conditions were supported on raschig rings. The TiO2 photocatalyzed degradation is enhanced in the vicinity of the surfactant critical micelle value. Further increase on the surfactant concentration leads to a loss in photodegradation performance up to values equivalent to that observed without surfactant. Surfactant influence can be explained by two different phenomena taking place. The increasing concentration of surfactant leads to an increase in micellar concentration, inducing the incorporation of the dye to the hydrophobic moiety of the micelles, rendering the hydroxyl radical unable to interact with the dye. Similarly, the increased concentration of micelles at the photocatalyst/water interface might lead to a decrease in the number of active sites on the TiO2 surface able to either generate reactive species and/or interact with de dye molecules. Additives such as H2 O2 , NaCl, Na2 SO4, and Na2 CO3 are able to override the influence of the surfactant both positively and negatively, being the final outcome of the influence highly dependent on the crystalline form of the TiO2 photocatalyst.

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As a model for the removal of complex organic contaminants from industrial water effluents, the heterogeneous photocatalytic degradation of Rhodamin 6G was studied using TiO2-derived catalysts, incorporated in water as suspension as well as supported in raschig rings. UV and Visible light were tested for the photo-degradation process. TiO2 catalysts were synthesized following acid synthesis methodology and compared against commercial TiO2 catalyst samples (Degussa P25 and Anatase). The bandgap (Eg) of the TiO2 catalysts was determined, were values of 2.97 and 2.98 eV were obtained for the material obtained using acid and basic conditions, respectively, and 3.02 eV for Degussa P25 and 3.18 eV for anatase commercial TiO2 samples. Raschig rings-supported TiO2 catalysts display a good photocatalytic performance when compared to equivalent amounts of TiO2 in aqueous suspension, even though a large surface area of TiO2 material is lost upon support. This is particularly evident by taking into account that the characteristics (XRD, RD, Eg) and observed photodegradative performance of the synthesized catalysts are in good agreement with the commercial TiO2 samples, and that the RH6G photodegradation differences observed with the light sources considered are minimal in the presence of TiO2 catalysts. The presence of additives induce changes in the kinetics and efficiency of the TiO2-catalyzed photodegradation of Rh6G, particularly when white light is used in the process, pointing toward a complex phenomenon, however the stability of the supported photocatalytic systems is acceptable in the presence of the studied additives. In line with this, the magnitude of the chemical oxygen demand, indicates that, besides the different complex photophysical processes taking place, the endproducts of the considered photocatalytic systems appears to be similar.

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Alkaline leaching with highly selective ammoniacal complexing agents is an interesting alternative for the treatment of copper concentrates. This treatment is beneficial for copper recovery because it allows the formation of soluble amines complexes, with cupric tetramine (  Cu ( NH 3 ) 4 2 + ) being the most stable. In order to suppress the unit operation of solvent extraction (SX) and move directly to the electrochemical process, an electro-electrodialysis (EED) process using ion exchange membranes to obtain copper is proposed. The study contemplates the operation with synthetic ammonia solutions containing copper at different concentrations and current density under standard conditions of pressure and temperature. The presented data demonstrate that the concentration of copper in the solution and the excess of ammonia are inversely related to the efficiency of the current and the voltage of the cell, whereas an increase in current density causes an increase in current efficiency, contrary to what happens in sulfuric systems.

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Nucleophilic aromatic substitution reactions of 4-chloroquinazoline toward aniline and hydrazine were used as a model system to experimentally show that a substrate bearing heteroatoms on the aromatic ring as substituent is able to establish intramolecular hydrogen bond which may be activated by the reaction media and/or the nature of the nucleophile.

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ß-lactam antibiotics, such as penicillin share a very unstable chemical structure. In water-based solutions, such as those used for clinical applications, the ß-lactam ring is readily opened due to a nucleophilic or electrophilic attack, leading to the loss of antimicrobial activity. Since the achievement and maintenance of optimum therapeutic levels of ß-lactam antibiotics is critical for the resolution of many infectious clinical situations, and to avoid antibiotic resistance generation, the design of new non-aqueous dosage forms is urgent. Recently, natural deep eutectic solvents (NADES) have emerged as alternative non-toxic and non-aqueous solvents for different biomedical applications. In this work, we formulated and characterized a NADES composed by betaine and urea (BU). Using this solvent, we evaluated the stability of clavulanic acid (CLV) and imipenem (IMP) and characterized their antimicrobial activities calculating the minimal inhibitory concentration. Characterization of BU solvent by infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR) indicated that the obtained solvent has a microstructure mainly based on hydrogen bonding interactions and water addition strongly affects its dynamic. The stability of ß-lactam antibiotic IMP and CLV using this solvent was increased by 7 fold and 2.5 fold respectively compared to water when analysed seven days after being dissolved. Microbiological assays showed that antibacterial activity at day seven was significantly decreased for both CLV and IMP when dissolved in water, while no change in their antibacterial properties was observed when antibiotics were dissolved in BU. The increased stability of IMP and CLV in BU may be related to the inert behaviour of the solvent and the higher dynamic restriction that helps antibiotics to maintain a more stable conformation. These data suggest the potential use of BU as a solvent to prevent degradation of ß-lactam antibiotics.

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There are numerous studies on systems comprising an enzyme encapsulated in unilamellar liposomes and its substrate initially present in the external aqueous media. Most of these studies are focused on enzyme stability and activity in a restricted media. However, the rate of the process is also determined by the capacity of the substrate to permeate towards the liposome inner pool. In spite of this, there are few studies aimed at a quantitative evaluation of the substrate permeation rate and its lifetime inside the liposome pool. In the present work, we describe, in terms of a very simple mechanism, the permeation of glucose and hydrogen peroxide in DPPC unilamellar liposomes. To this aim, we evaluated the rate of the process employing encapsulated glucose oxidase and catalase in the kinetic diffusion controlled limit. Under this condition, the rate of the process becomes zero order in the enzyme and allows a direct evaluation of the rate constant for the permeation process and the lifetime of a substrate molecule incorporated into the liposome inner pool.

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Sticholysin II (St II) is a haemolytic toxin isolated from the sea anemone Stichodactyla helianthus. The high haemolytic activity of this toxin is strongly dependent on the red cell status and the macromolecule conformation. In the present communication we evaluate the effect of human serum albumin on St II haemolytic activity and its capacity to form pores in the bilayer of synthetic liposomes. St II retains its pore forming capacity in the presence of large concentrations (up to 500 µM) of human serum albumin. This effect is observed both in its capacity to produce red blood cells haemolysis and to generate functional pores in liposomes. In particular, the capacity of the toxin to lyse red blood cells increases in the presence of human serum albumin (HSA). Regarding the rate of the pore forming process, it is moderately decreased in liposomes and in red blood cells, in spite of an almost total coverage of the interface by albumin. All the data obtained in red cells and model membranes show that St II remains lytically active even in the presence of high HSA concentrations. This stubbornness can explain why the toxin is able to exert its haemolytic activity on membranes immersed in complex plasma matrixes such as those present in living organisms.

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Changes in the intrinsic protein fluorescence with the additive concentration provide one of the most employed methodologies for the evaluation of the binding constant and the number of binding sites. In the last years, more than 175 studies have been published where the double logarithmic plot shown below is used toward determining the number of equivalent binding sites (n). Log [(F° - F)/F] = log K + n log [Q0 ]. However, the value of n evaluated by this procedure is unrelated to the number of equivalent binding sites; rather it represents the stoichiometry of the binding step. The confusion on the meaning of n arises upon assuming that the binding process is represented by the forward and backward elementary steps shown below, implying that binding of the n solutes takes place simultaneously, i.e. there are no intermediate species. nQ + P ⇆ Qn P. The conclusion that n is unrelated to the number of equivalent binding sites is supported by the fact that in all the systems considered (99% of them) n values are close to one and much smaller than those obtained by ultrafiltration. It is then remarkable, the profusion of publications in peer-reviewed, specialized journals including a conceptual error that confuses Hill's coefficient and/or the stoichiometry of the binding step with the number of independent binding sites. Here, we discuss the origin of this common misconception and provide alternative methods to determine the number of binding sites.

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The effect of human serum albumin (HSA) addition on the rate of hydrolysis of N-glutaryl-L-phenylalanine p-nitroanilide (GPNA) catalyzed by α-chymotrypsin has been measured in phosphate buffer saline at pH = 7.4. The presence of HSA (up to 200 µM) leads to a decrease in the rate of the process. The reaction follows a Michaelis-Menten mechanism under all the conditions employed. To take into account the effect of substrate depletion due to its binding to albumin ultrafiltration experiments were carried out from which the binding of GPNA to HSA was derived. After correction of the kinetic data taking into account the binding of GPNA to HSA, the activity of the enzyme, and the derived Michaelis constant and catalytic rate constant tends to remain almost independent of the presence of albumin, indicating that the depletion of the substrate due to its binding to HSA is the main factor affecting the enzyme activity.

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Este estudio tiene por objetivo mostrar la influencia de la cátedra de Educación Física en los estilos de vida de la población escolar del Departamento del Huila. El presente es un estudio de tipo descriptivo transversal. 255.194 escolares del Departamento del Huila. Se consideraron los docentes de las instituciones educativas que participaron en el estudio. Para el cálculo del tamaño de la muestra se utilizó el programa MacStat 2.0 con una P de 0,5, nivel de confianza de 95% (t=1,96) y un e de 0,04, lo cual arrojó un tamaño de muestra de 589 estudiantes. Se utilizó el (International Physical Activity Questionnaire - IPAQ Formato Corto). Para evaluar la percepción de los estudiantes y los docentes se utilizó como técnica la encuesta y como instrumento un cuestionario.Se encontró que la clase de Educación Física ha influido en el estudiante para la realización de actividad física, pero no de manera determinante; falta cultura sobre salud y actividad física en los docentes. Deben innovar y ser más creativos a la hora de incentivar a los niños para la práctica de actividades no sedentarias.

To establish the influence of the physical education classes in the lifestyles of the students in the Department of Huila. This is a descriptive cross-sectional study 255.194 students from the department of Huila. The teachers of the participant educative institutions were taken into account in the study. To calculate the size of the sample the Mac Stat 2.0 program was used with a P of 0,5, a trust level of 95% (t=1,96) and e of 0,04 which gave a sample size of 589 students.Was used the international physical activity questioner IPAQ to eva luate the student’s and teacher’s perceptions, the technique used was the survey and as instrument a questionnaire.The physical education classes have the students to do physical activities, but not in a determinate way, there is a lack of culture about health and physical activity in teachers. They should innovative and be more creative when fostering non-sedentary activities in boys and girls.

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The rate of N-glutaryl-L-phenylalanine p-nitroanilide hydrolysis catalyzed by alpha-chymotripsin has been measured in aqueous solutions of cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and dodecyltrimethylammonium bromide at concentrations below and above their critical micellar concentrations (CMC). For the three surfactants considered superactivity was observed, with maximum catalytic efficiencies taking place near the corresponding CMCs. The effect of the surfactants after the CMCs is mostly due to a decreased thermodynamic activity of the substrate due to its incorporation into the micelles. After addition of the surfactants, the Michaelis constant values (corrected to take into account the free substrate concentration) tend to decrease, passing through an ill defined minimum, afterwards reaching a constant value. The catalytic rate constants show the same profiles that the catalytic efficiency, being maxima near the surfactants CMCs. This maximum is more important for the surfactant having the shorter tail. This result is explained by considering that the hydrophobicity of the surfactant influences more the CMC than its association to the enzyme.

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