Abstract Introduction and Objective: There is an important worldwide demand to develop biological substitutes that restore, maintain or improve tissue function based on the combined use of biomaterials that function as scaffolds, using cells that induce regeneration, to repair injured or diseased tissues. Our objective is to culture and characterize the Wharton gelatin epidermal and mesenchymal cells on ultrathin chitosan matrices in order to evaluate the biocompatibility and its potential use as dermal substitutes. Methods: Two cellular models of human origin were used with the prior informed consent of healthy donors, mesenchymal stem cells obtained from Wharton's gelatin and epidermal cells, isolated by digestion with dispase of skin samples. Both cell types planted at a rate of 5,000 cel/cm2 and cell adhesion was evaluated by the quantitative CellTiter 96® (MTS) method and qualitatively using the DAPI labeling of the cell nuclei. Results: Through this study, homogenous cultures of both cell types, keratinocytes and mesenchymal stem cells were established. The 2 cell types showed an appropriate cellular adhesion and viability on the ultrathin membranes of chitosan, both by the MTS assay and by the qualitative evaluation with DAPI. Conclusions: It was demonstrated that chitosan membranes can be used as appropriate supports for these cell types, which could be used as living dermal dressings in the treatment of chronic ulcers and burns, since the system combines the regenerative and bacteriostats properties of chitosan with high cutaneous regenerative potential presented by both mesenchymal stem and epidermal cells.

Resumen Introducción y Objetivo: Existe una importante demanda mundial para desarrollar sustitutos biológicos que restauren, mantengan o mejoren la función tisular, basándose en el uso combinado de biomateriales que funcionen como andamios y empleando células que induzcan regeneración para reparar los tejidos lesionados o enfermos. El objetivo de este estudio es cultivar y caracterizar células epidérmicas y mesenquimales de gelatina de Wharton sobre matrices de quitosano ultradelgadas con la finalidad de evaluar la biocompatibilidad y su potencial uso como sustitutos dérmicos. Material y Método: Empleamos 2 modelos celulares de origen humano previo consentimiento informado de los donantes sanos, células madre mesenquimales obtenidas a partir de gelatina de Wharton y células epidérmicas aisladas mediante digestión con dipasa de muestras de piel. Sembramos ambos tipos celulares en proporción de 5.000 cel/cm2 y evaluamos la adhesión celular por método cuantitativo CellTiter 96® (MTS) y cualitativamente empleando marcaje con DAPI de los núcleos celulares. Resultados: Logramos establecer cultivos homogéneos de ambos tipos celulares, queratinocitos y células madre mesenquimales a partir de gelatina de Wharton. Los dos tipos celulares mostraron una apropiada adhesión celular y viabilidad, tanto por el ensayo de MTS como por la evaluación cualitativa con DAPI, sobre las membranas ultradelgadas de quitosano. Conclusiones: Demostramos que las membranas de quitosano pueden emplearse como soportes apropiados para estos tipos celulares, los cuales podrían utilizarse como apósitos dérmicos vivos en el tratamiento de úlceras crónicas y quemaduras, ya que el sistema combina las propiedades regenerativas y bacteriostáticas del quitosano con el alto potencial regenerativo cutáneo que presentan tanto las células madre mesenquimales como las células epidérmicas.

T. margaritae cumple un papel importante en la descomposición de restos vegetales y animales en las costas venezolanas. El objetivo fue determinar las diferencias en la composición lipídica entre sexos y talla de la especie. Para esto, especímenes de T. margaritae fueron recolectados en la zona supralitoral de dos playas arenosas: Mangle Quemao y las Mercedes de Paparo. Posteriormente se separaron por talla y sexo determinándoles su peso, densidad, biomasa y perfil lipídico. Todas las categorías presentaron tallas similares entre localidades. Los pesos fueron superiores en los organismos de Mangle Quemao. Los lípidos totales presentaron proporciones similares entre sexos, talla y localidad (3-5%), al igual que los fosfololípidos (20-30%), glicolípidos (<1%) y esteroles (4%), exceptuando los triglicéridos (TAG), siendo estos superiores en Mangle Quemao. Esto último pudiendo estar relacionado con la diferencia de pesos entre localidades. Los ácidos grasos más abundantes en ambas localidades fueron 16:0 y 18:1(n-9). Se identificaron otros 9 marcadores con variaciones en su distribución. Con base en los biomarcadores se puede catalogar a T. margaritae como una especie carnívora- generalista, siendo sus poblaciones influenciadas por la disponibilidad de alimento que a su vez, podría inducir diferencias de peso, TAG y biomarcadores.

Lipids in the amphipod Talorchestia margaritae (Amphipoda: Talitridae) and its relationship with the ecology of the species. T. margaritae, an endemic species inhabiting Venezuelan coasts, plays an important ecological role in plant and animal decomposition. To understand this issue in some animal groups, especially small ones, lipid composition analysis has been an interesting tool to describe their trophic relationships and food preferences. In order to assess this and visualize the components of their diet, we determined the lipid composition differences between males and females and among age classes in this species. Two sandy beaches were selected: Mangle Quemao and Las Mercedes de Paparo, from which sand samples of known volume were collected at the supralittoral area in 2007. Organisms were separated by age and sex classes, and their size, weight, density, biomass, total lipids (TL), lipid classes and fatty acid markers present in their tissues were determined. The sizes were similar for all age classes between the two locations, while the weights were higher for Mangle Quemao. The TL and lipid classes showed similar proportions between sexes, age classes and locations (TL: 3-5%; Phospholipids: 20-30%; Glycolipids: <1%; sterols: 4%). On the other hand, Triglycerides (TAG) were higher in Mangle Quemao, which may be related to the difference between the weights of two locations. The most abundant fatty acid biomarkers in the two studied sites were 16:0 and 18:1(n-9); this last one is characteristic of a carnivorous diet. The other nine markers were identified with changes in their distribution in organisms at Mangle Quemao and between males and females of both populations. Based on observed fatty acids markers we can assume T. margaritae as a generalist carnivore. Those populations were influenced by available food; inducing differences in weight, TAG proportion and markers diversity. Rev. Biol. Trop. 58 (3): 841-855. Epub 2010 September 01.

Trypanosoma cruzi epimastigotes were extracted under various conditions in order to examine the role of divalent cations in the solubilization of microtubule proteins. When epimastigotes were homogenized in the presence of 5 mM Mg+2 and 5 mM Ca+2, a protein kinase responsible for phosphorylating tubulin, as well as the tubulin that became phosphorylated, remained tightly associated with the parasite particulate and detergent-resistant fractions. On the contrary, tubulin kinase and its substrate were predominantly released into the parasite cytosolic and detergent-soluble fractions, when epimastigotes were extracted in the presence of 5 mM EDTA and 5 mM EGTA. These evidences demonstrated a divalent cation-dependent solubilization of the enzyme responsible for the phosphorylation of tubulin in T. cruzi epimastigotes and suggested a tight association between tubulin and this kinase. Under all conditions tested, tubulin kinase activity in epimastigote extracts was lower than the addition of the corresponding value in the parasite cytosolic and membranous fractions, suggesting the presence of a kinase inhibitor or regulatory subunit which also seemed to be modulated by divalent cations. Additionally, inhibition experiments in the presence of heparin, 2,3-bisphosphoglycerate and GTP established that the parasite tubulin kinase corresponded to a protein kinase CK2