Abstract Background: Amphibians inhabit the terrestrial environment, a conquest achieved after several evolutionary steps, which were still insufficient to make them completely independent of the aquatic environment. These processes gave rise to many morphological and physiological changes, making their skin (and cutaneous secretion) rich in bioactive molecules. Among the tree frogs, the secretion is composed mainly of peptides; but alkaloids, proteins and steroids can also be found depending on the species. The most known class of biologically active molecules is the antimicrobial peptides (AMPs) that act against bacteria, fungi and protozoans. Although these molecules are well-studied among the hylids, AMPs ontogeny remains unknown. Therefore, we performed peptidomic and proteomic analyses of Pithecopus nordestinus (formerly Phyllomedusa nordestina) in order to evaluate the peptide content in post-metamorphosed juveniles and adult individuals. Methods: Cutaneous secretion of both life stages of individuals was obtained and analyzed by LC-MS/MS after reduction and alkylation of disulfide bonds or reduction, alkylation and hydrolysis by trypsin. Results: Differences in the TIC profile of juveniles and adults in both treatments were observed. Moreover, the proteomic data revealed known proteins and peptides, with slight differences in the composition, according to the life stage and the treatment. AMPs were identified, and bradykinin-potentiating peptides were observed in trypsin-treated samples, which suggests a protein source of such peptide (cryptide). Conclusion: In general, skin secretion contents were similar between juveniles and adults, varying in quantity, indicating that the different stages of life are reflected in the number of molecules and not on their diversity.

El hipotiroidismo es un trastorno endocrino en el cual la glándula tiroides tiene su función disminuida; teniendo como consecuencia paralela la perdida de homeostasia del cuerpo alterando así su adecuado funcionamiento. Para diagnosticar la enfermedad, sumado a la clínica, se recurre a medir los niveles sanguíneos de hormonas tiroideas. Como el sistema cardiovascular y la glándula tiroides están relacionados fisiológicamente, los trastornos de la glándula tiroides afectan de gran manera al sistema cardiovascular. Se detallan los mecanismos intracelulares y extracelulares de las hormonas tiroideas; y, utilizando esta información, se explican todos los cambios morfológicos y fisiológicos que esta patología causa en el corazón y en las células de músculo liso. Además, se dan a conocer las implicaciones que la enfermedad tiene a nivel del miocardio, sobre la hemodinámica, su relación con la insuficiencia cardíaca congestiva, la hipertensión y los efectos en general sobre los vasos sanguíneos, con el objetivo de describir la relación entre hipofunción tiroidea clínica y subclínica como factor de riesgo determinante para el desarrollo de alteraciones cardiovasculares.

Hypothyroidism is an endocrine disorder in which the thyroid gland has a diminished function; having as a consequence the loss of homeostasis of the body, therefore, altering its proper functioning. To diagnose this disease, physical examination, blood tests and thyroid stimulating hormone tests are utilized. Since the cardiovascular system and the thyroid gland are physiological related, the general disorders of the thyroid gland greatly affect the cardiovascular system. The intracellular and extracellular mechanisms of thyroid hormones are detailed; and, using this information, all the morphological and physiological changes that this pathology causes in the heart and on smooth muscle cells are explained. In addition, the implications of the disease on the myocardium, on hemodynamics, its relation to congestive heart failure, hypertension and general effects on blood vessels are revealed, with the objective of describing the relationship between clinical and subclinical thyroid hypofunction as a determining risk factor for the development of cardiovascular disorders.

Abstract The objective of the present work was to characterize the agricultural production systems of the municipality Morelos, Zacatecas and to calculate the profitability of its three main crops (beans, maize, and chili) under a conventional system during the agricultural year 2013. A simple random sampling was carried out with 26 farmers producing all three crops during the same agricultural cycle. The producers were typified, and the production costs per hectare, the profitability percentage, and the benefit-cost ratio (B/C) were estimated. The results show that the three crops are profitable. The cultivation of chili is the one that requires a greater investment, but it is the one that generates greater yields. It was also observed that the experience of producers, the incorporation of new technologies, and some practices of soil conservation are factors that allow a high level of productivity of the municipality.

Resumen El objetivo del presente trabajo fue caracterizar los sistemas de producción agrícola del municipio de Morelos, Zacatecas, y calcular la rentabilidad de sus tres principales cultivos (frijol, maíz y chile), bajo un sistema convencional, durante el año agrícola 2013. Se realizó un muestreo aleatorio simple a 26 agricultores que producen los tres cultivos durante el mismo ciclo agrícola. Se tipificaron a los productores y se estimaron los costos de producción por hectárea, el porcentaje de rentabilidad y la relación beneficio-costo (B/C). Los resultados demuestran que los tres cultivos son rentables. El cultivo de chile es el que requiere de una inversión mayor, pero es el que genera la rentabilidad más alta. De igual forma, se observó que la experiencia de los productores, la incorporación de nuevas tecnologías y algunas prácticas de conservación del suelo son factores que permiten un alto nivel de productividad del municipio.

Resumen En este trabajo se propone un método integrado para la estimación de la competitividad de fabricación de las empresas utilizando su rendimiento comparativo en sus objetivos de fabricación. El método desarrollado utiliza un extenso análisis de la literatura, junto con un análisis de expertos a través del método Delphi para identificar los factores que influyen en la competitividad de la industria bajo estudio. Diferentes coeficientes estadísticos tales como el alfa de Cronbach, W de Kendall, kappa de Fleiss y la correlación intraclase se utilizan para asegurar la fiabilidad de los instrumentos y de la opinión de los expertos. El análisis exploratorio de factores (EFA por sus siglas en inglés) y un posterior análisis factorial confirmatorio (CFA por sus siglas en inglés) se utilizan como el medio para obtener el modelo de medición con el que se calcula un indicador de la competitividad de fabricación. Un caso de estudio empírico utilizando el método propuesto se lleva a cabo en una muestra de plantas maquiladora de ropa.

Abstract This paper proposes an integrated method for estimating the manufacturing competitiveness of companies using their comparative performance in their manufacturing objectives. The developed method uses an extensive analysis of the literature along with expert analysis through the Delphi method to identify the factors influencing competitiveness in the industry under study. Different statistical coefficients such as Cronbach’s alpha, Kendall’s W, Fleiss’ kappa and Intraclass Correlation are used to assure reliability in the instruments and the experts’ opinion. Exploratory factor analysis (EFA) and a subsequent confirmatory factor analysis (CFA) are used as the means to obtain the measurement model with which to calculate an indicator of manufacturing competitiveness. An empirical case study using the proposed method is performed in a sample of apparel maquiladora plants.

Abstract Background Rabies is an incurable neglected zoonosis with worldwide distribution characterized as a lethal progressive acute encephalitis caused by a lyssavirus. Animal venoms and secretions have long been studied as new bioactive molecular sources, presenting a wide spectrum of biological effects, including new antiviral agents. Bufotenine, for instance, is an alkaloid isolated from the skin secretion of the anuran Rhinella jimi that inhibits cellular penetration by the rabies virus. Antimicrobial peptides, such as ocellatin-P1 and ocellatin-F1, are present in the skin secretion of anurans from the genus Leptodactylus and provide chemical defense against predators and microorganisms. Methods Skin secretion from captive Leptodactylus labyrinthicus was collected by mechanical stimulation, analyzed by liquid chromatography and mass spectrometry, and assayed for antiviral and cytotoxic activities. Synthetic peptides were obtained using solid phase peptide synthesis, purified by liquid chromatography and structurally characterized by mass spectrometry, and assayed in the same models. Cytotoxicity assays based on changes in cellular morphology were performed using baby hamster kidney (BHK-21) cells. Fixed Rabies virus (Pasteur Virus – PV) strain was used for virological assays based on rapid fluorescent focus inhibition test. Results Herein, we describe a synergic effect between ocellatin-F1 and bufotenine. This synergism was observed when screening the L. labyrinthicus skin secretion for antiviral activities. The active fraction major component was the antimicrobial peptide ocellatin-F1. Nevertheless, when the pure synthetic peptide was assayed, little antiviral activity was detectable. In-depth analyses of the active fraction revealed the presence of residual alkaloids together with ocellatin-F1. By adding sub-effective doses (e.g. < IC50) of pure bufotenine to synthetic ocellatin-F1, the antiviral effect was regained. Moreover, a tetrapetide derived from ocellatin-F1, based on alignment with the virus’s glycoprotein region inferred as a possible cell ligand, was able to maintain the synergic antiviral activity displayed by the full peptide. Conclusions This novel antiviral synergic effect between a peptide and an alkaloid may present an innovative lead for the study of new antiviral drugs.

Background Rabies is a fatal zoonotic neglected disease that occurs in more than 150 countries, and kills more than 55.000 people every year. It is caused by an enveloped single stranded RNA virus that affects the central nervous system, through an infection initiated by the muscular nicotinic acetylcholine receptor, according to many authors. Alkaloids, such as acetylcholine, are widespread molecules in nature. They are present in numerous biological fluids, including the skin secretion of many amphibians, in which they act (together with proteins, peptides and steroids) as protection agents against predators and/or microorganisms. Among those amphibians that are rich in alkaloids, there is the genus Rhinella.Methods Bufotenine was isolated from Rhinela jimi skin secretion after a liquid-liquid partition (H2O:CH2Cl2) and reversed phase high-performance liquid chromatography analyses (RP-HPLC). Bufotenine was also extracted from seeds of Anadenanthera colubrina in acetone solution and purified by RP-HPLC, as well. Structural characterization was performed by mass spectrometry and nuclear magnetic resonance analyses. Cytotoxic tests of bufotenine were performed over baby hamster kidney (BHK-21) cells using MTT test. For the antiviral activity,Rabies virus strain Pasteur vaccine (PV) was used on fluorescence inhibition test and fluorescent foci inhibition test, with both simultaneous and time course treatment of the cells with the virus and bufotenine.Results In the present work we describe the effects of bufotenine, obtained either from toads or plants, that can inhibit the penetration of rabies virus in mammalian cells through an apparent competitive mechanism by the nicotinic acetylcholine receptor. Moreover, this inhibition was dose- and time-dependent, pointing out to a specific mechanism of action.Conclusions This work do not present or propose bufotenine as a drug for the treatment of rabies due to the hallucinogen and psychotropic effects of the molecule. However, continued studies in the elucidation of the antiviral mechanism of this molecule, may lead to the choice or development of a tryptamine analogue presenting potential clinical use.

Background Among the tropical parasitic diseases, those caused by protozoans are considered a challenge to public health, being represented by leishmaniasis and Chagas disease. In view of the low effectiveness and toxicity of the current therapy, animal venoms such as amphibian secretions have been used as a promising source of new drug prototypes. The present work aimed to achieve bioguided fractionation of metabolites present in a cutaneous secretion of the caecilian Siphonops annulatus (Amphibia: Gymnophiona: Siphonopidae) with antileishmanial and antitrypanosomal activity.Methods Through liquid-liquid partition and chromatographic techniques, the secretion was fractionated using bioguided assays. The 50% inhibitory concentration (IC50) of the main fraction (SaFr1) was studied against Leishmania (L.) infantumpromastigotes and intracellular amastigotes, trypomastigotes ofTrypanosoma cruzi and mammalian cells; viability was detected by the colorimetric MTT assay. By using a spectrofluorimetric assay with the probe SYTOX® Green and transmission electron microscopy (TEM), we also investigated the potential damage caused by SaFr1 in the plasma membrane and mitochondria of Leishmania.Results The bioguided assay enabled isolation of a highly purified fraction (SaFr1) with an IC50 of 0.065 μg/mL against promastigotes and 2.75 μg/mL against trypomastigotes. Due to its high toxicity to peritoneal macrophages, SaFr1 showed no selectivity towards the intracellular forms ofLeishmania. Ultrastructural studies withLeishmania demonstrated severe mitochondrial damage and the formation of large cytoplasmic vacuoles, leading to the parasite’s death within a few hours. Nevertheless, it caused no alteration in the plasma membrane permeability as detected by the fluorescent probe and TEM.Conclusions The present study demonstrated for the first time the antiparasitic activity of the skin secretion of the caecilian S. annulatus againstLeishmania and T. cruzi, confirming that skin secretions of these amphibians, similarly to those of anurans and salamanders, are also potential tools for the development of new drug candidates against neglected diseases.