1,772 research outputs found
Tunable injectable alginate-based hydrogel for cell therapy in Type 1 Diabetes Mellitus
Islet transplantation has the potential of reestablishing naturally-regulated insulin production in Type 1 diabetic patients. Nevertheless, this procedure is limited due to the low islet survival after transplantation and the lifelong immunosuppression to avoid rejection. Islet embedding within a biocompatible matrix provides mechanical protection and a physical barrier against the immune system thus, increasing islet survival. Alginate is the preferred biomaterial used for embedding insulin-producing cells because of its biocompatibility, low toxicity and ease of gelation. However, alginate gelation is poorly controlled, affecting its physicochemical properties as an injectable biomaterial. Including different concentrations of the phosphate salt Na2HPO4 in alginate hydrogels, we can modulate their gelation time, tuning their physicochemical properties like stiffness and porosity while maintaining an appropriate injectability. Moreover, these hydrogels showed good biocompatibility when embedding a rat insulinoma cell line, especially at low Na2HPO4 concentrations, indicating that these hydrogels have potential as injectable biomaterials for Type 1 Diabetes Mellitus treatment
Modelo competitivo de variables jerárquicas de empresas exportadoras
el objetivo de esta ponencia es describir la competitividad de empresas exportadoras del sector aguacatero, mostrando sus problemáticas, organización, objetivos, producción, y la capacidad de exportar de manera eficiente a Estados Unidos. Se considera el estudio de la competitividad de 25 empresas exportadoras de aguacate, con información de su organización, sus objetivos, su producción y la capacidad de exportar de manera eficiente. La investigación documental se enfocó en el conocimiento de las principales teorías sobre la competitividad empresarial y obtener como resultado su conceptualización y la medición de las variables que lo afectan. la técnica de jerarquización analítica se utiliza para evaluar la importancia de los problemas planteados y las causas del mismo. el método consiste en realizar comparaciones por pares entre cada una de las alternativas, que en este caso son variables, y por medio de una escala previamente específica se evalúan las magnitudes de preferencia
Intentional replantation: case report
Intentional reimplantation is a procedure in which an intentional tooth extraction is performed followed by reinsertion of the extracted tooth. We present the case of a 50-year-old male patient who came to the consultation due to incrustation detachment in tooth #37, when performing the radiographic study an extensive apical lesion was observed in tooth #36 with a sinuous path and the presence of purulent exudate. The tooth #36 was extracted, apicoectomy, retro preparation and retrograde filling were carried out for later reimplantation, showing bone regeneration after one year of evolution
Flujo vaginal. Experiencia con el diagnóstico microbiológico de 1178 casos
During the year 1985 we studied 1178 adult women, from the laboratory viewpoint, in order to define the. etiology of their vaginal discharge; in 25,3% we established the diagnosis of bacterial vaginosis (Gardnerella vaginalis associated vaginitis); in 13,9% we found candidiasis and in 2,9% trichomoniasis; the remaining 54,2% did not fit any of these categories; three patients revealed either Geotrichurn or Trichosporon the significance of which in the vagina is unknown and should be further studied.En 1985 estudiamos, desde el punto de vista del laboratorio, 1178 mujeres adultas para definir la etiología de su flujo vaginal; se diagnosticó vaginosis bacteriana (vaginitis asociada a Gardnerella vaginalis) en 25.3% de los casos, candidiasis en 13,9% y Tricomoniasis en 2.9% en tres pacientes había levaduras de los géneros Geotrichum o Trichosporon cuyo significado en la vagina es desconocido y amerita ser estudiado
Morphological, Electrical, and Chemical Characteristics of Poly(sodium 4-styrenesulfonate) Coated PVDF Ultrafiltration Membranes after Plasma Treatment
A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinylidene fluoride) (PVDF), was recovered with a negatively-charged polyelectrolyte (poly(sodium 4-styrenesulfonate)) (PSS), and the effects on its electric, chemical, and morphological properties were analyzed. Atomic force microscopy (AFM), liquid-liquid displacement porometry, Electrical Impedance Spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the modifications induced by the deposition of PSS on the PVDF positively-charged membrane and after its treatment by a radio frequency Ar-plasma. These techniques confirmed a real deposition and posterior compaction of PSS with increasing roughness and decreasing pore sizes. The evolution of the electric resistances of the membranes confirmed crosslinking and compaction with shielding of the sulfonated groups from PSS. In this way, a membrane with a negatively-charged active layer and a pore size which was 60% lower than the original membrane was obtained. The composition of the additive used by manufacturers to modify PVDF to make it positively charged was obtained by different procedures, all of which depended upon the results of X-ray photoelectron spectroscopy, leading to fairly consistent results. This polymer, carrying positive charges, contains quaternary nitrogen, as confirmed by XPS. Moreover, Raman spectroscopy confirmed that PVDF changes from mostly the β to the α phase, which is more stable as a substrate for the deposited PSS. The aim of the tested modifications was to increase the retention of divalent anions without reducing permeability.Fil: Sandoval Olvera, Ivette G.. Universidad de Guanajuato; MéxicoFil: González Muñoz, Pilar. Universidad de Guanajuato; MéxicoFil: Diaz, Dario Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Maroto Valiente, Ángel. Universidad de Guanajuato; MéxicoFil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Carmona, Francisco J.. Universidad de Extremadura; EspañaFil: Palacio, Laura. Universidad de Valladolid. Facultad de Ciencias; EspañaFil: Calvo, José I.. Universidad de Valladolid. Facultad de Ciencias; EspañaFil: Hernández, Antonio. Universidad de Valladolid. Facultad de Ciencias; EspañaFil: Ávila Rodríguez, Mario. Universidad de Guanajuato; MéxicoFil: Prádanos, Pedro. Universidad de Valladolid. Facultad de Ciencias; Españ
Specific Recognition of Influenza A/H1N1/2009 Antibodies in Human Serum: A Simple Virus-Free ELISA Method
Although it has been estimated that pandemic Influenza A H1N1/2009 has infected millions of people from April to October 2009, a more precise figure requires a worldwide large-scale diagnosis of the presence of Influenza A/H1N1/2009 antibodies within the population. Assays typically used to estimate antibody titers (hemagglutination inhibition and microneutralization) would require the use of the virus, which would seriously limit broad implementation.An ELISA method to evaluate the presence and relative concentration of specific Influenza A/H1N1/2009 antibodies in human serum samples is presented. The method is based on the use of a histidine-tagged recombinant fragment of the globular region of the hemagglutinin (HA) of the Influenza A H1N1/2009 virus expressed in E. coli.The ELISA method consistently discerns between Inf A H1N1 infected and non-infected subjects, particularly after the third week of infection/exposure. Since it does not require the use of viral particles, it can be easily and quickly implemented in any basic laboratory. In addition, in a scenario of insufficient vaccine availability, the use of this ELISA could be useful to determine if a person has some level of specific antibodies against the virus and presumably at least partial protection
Biofortification with magnesium nanofertilizer on bioactive compounds and antioxidant capacity in green beans
The use of nanofertilizers has the potential to be used to enrich edible organs with nutrients (biofortification) and improve the biosynthesis of bioactive compounds and their antioxidant capacity. Therefore, the objective of this study was to evaluate the effect of biofortification with magnesium (Mg) nanofertilizer on the accumulation of bioactive compounds and antioxidant capacity in green bean cv. Strike compared to a conventional fertilizer (Mg sulfate). Two sources of Mg were applied via foliar: Nanofertilizer and Mg Sulfate at doses of 0, 50, 100, 200, and 300 mg/L of Mg. The accumulation of total polyphenols, flavonoids, anthocyanins, bioactive compounds, and antioxidant capacity was evaluated in pods. The results obtained in this research confirm the effect of green bean pods biofortified with Mg nanofertilizers on the production and accumulation of bioactive compounds and antioxidant capacity, improving the nutrition and nutraceutical quality of green beans. The 50 mg/L dose of Mg nanofertilizer was the most effective treatment to increase bioactive compounds and antioxidant capacity compared to high doses of Mg sulfate (300 mg/L). This is one of the first studies focused on biofortification with Mg nanofertilizers and their effect on the nutraceutical quality of green beans
Evaluation of chromosome organization and microtubule arrangement in goat (capra aegragrus) oocytes after vitrification, in vitro maturation and fertilization, and early embryo development
Objective: Evaluate the use of Ethylene Glycol (EG), Dimethyl Sulfoxide (DMSO), Sucrose and Fetal Bovine Serum (FBS) as cryoprotectants and their effect on the organization of chromosomes and the arrangement of microtubules, during the vitrification process in goat oocytes matured in vitro and in the development of preimplantation embryos produced in vitro.
Design/methodology/approach: In vitro matured oocytes were divided into 3 groups (control group, cryoprotectant exposed group, vitrified group). A mixture of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS was used for the vitrification using the Cryotop device. In vitro matured oocytes were warmed and afterwards each group was divided into two more groups. Both groups were subjected to immunofluorescence, the first group to observe the damage produced to the chromosomes and microtubules and the second group to observe the effect on the in vitro embryo development.
Results: The combined use of 15% EG, 15% DMSO, 0.4 M Sucrose and 20% FBS during vitrification did not prevent cryoinjuries in goat oocytes and in vitro produced embryos, since embryo development was disrupted before the blastocyst stage by stopping cleavage at the morula stage. This disruption was associated with chromosome decondensation and the absence of a microtubule network, thereby hindering chromosomal segregation.
Limitations on study/implications: The effect of conventional cryoprotectants on chromosomes and microtubules arrangement on vitrified goat oocytes and in vitro embryo production.
Findings/conclusions: The combined use of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS as vitrification cryoprotectants did not prevent cryoinjuries in caprine oocytes and did not improve caprine embryo development in vitro
Functional traits determine plant co-occurrence more than environment or evolutionary relatedness in global drylands
Plant–plant interactions are driven by environmental conditions, evolutionary relationships (ER) and the functional traits of the plants involved. However, studies addressing the relative importance of these drivers are rare, but crucial to improve our predictions of the effects of plant–plant interactions on plant communities and of how they respond to differing environmental conditions. To analyze the relative importance of – and interrelationships among – these factors as drivers of plant–plant interactions, we analyzed perennial plant co-occurrence at 106 dryland plant communities established across rainfall gradients in nine countries. We used structural equation modelling to disentangle the relationships between environmental conditions (aridity and soil fertility), functional traits extracted from the literature, and ER, and to assess their relative importance as drivers of the 929 pairwise plant–plant co-occurrence levels measured. Functional traits, specifically facilitated plants’ height and nurse growth form, were of primary importance, and modulated the effect of the environment and ER on plant–plant interactions. Environmental conditions and ER were important mainly for those interactions involving woody and graminoid nurses, respectively. The relative importance of different plant–plant interaction drivers (ER, functional traits, and the environment) varied depending on the region considered, illustrating the difficulty of predicting the outcome of plant–plant interactions at broader spatial scales. In our global-scale study on drylands, plant–plant interactions were more strongly related to functional traits of the species involved than to the environmental variables considered. Thus, moving to a trait-based facilitation/competition approach help to predict that: (1) positive plant–plant interactions are more likely to occur for taller facilitated species in drylands, and (2) plant–plant interactions within woody-dominated ecosystems might be more sensitive to changing environmental conditions than those within grasslands. By providing insights on which species are likely to better perform beneath a given neighbour, our results will also help to succeed in restoration practices involving the use of nurse plants
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