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Browsing by Author "Restrepo Betancur, Giovanni"

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    Criopreservación de semen canino por congelación rápida por dimetilformamida
    (Corporación Universitaria Lasallista, 2011) Restrepo Betancur, Giovanni; Gómez Oquendo, Jorge; Vásquez Araque, Neil
    Introduction. Several factors influence the fertilizing capacity of cryopreserved canine semen. Structural alterations and the osmotic and toxic effects on sperm have focused interest on developing new cryopreservation and cryoprotection techniques with a bigger potential for conserving the semen´s fertilization capacity. Objective. To compare the effect of fast freezing with glycerol and dimethylformamide on the post-freezing quality of canine semen. Materials and methods. In a cryopreservation process by fast freezing, four treatments were implemented (glycerol at 3% and 5%, y dimethylformamide at 3% and 5%). After thawing, individual mobility, sperm morphology and the membrane´s integrity of sperm were evaluated. The statistic evaluation was made by the use of a variance analysis and a Fisher´s minimal significant difference test. Results. For the individual mobility, a superiority was found for the 5% glycerol (58%±7.8) over 5% DMF (44.5%±17.7), 3% glycerol (18%±10.1), and 3% DMF (11.8%±10.5). For the membrane´s integrity, 5%DMF had the highest media value (33.4%±9.7), above 3% glycerol (27.5%±4.3) y 3% DMF (24.2%±5.3), but it had no statistic difference over 5% glycerol (31.4%±3.8). For the sperm morphology, no statistic difference was found between 5% glycerol (67%±11.9), 3% glycerol (65.6±12.5), and 5%DMF (60%±16.5), but there was a difference between these and 3% DMF (50.1%±18.3). Conclusions. Glycerol and DMF, in 5% concentrations, provide a similar protection to semen during fast freezing cryopreservation.
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    Efecto de los suplementos fluido folicular y suero fetal bovino sobre la maduración in vitro de oocitos equinos
    (Corporación Universitaria Lasallista, 2011-06-03) Restrepo Betancur, Giovanni; Giraldo Giraldo, John Jairo; Gómez Oquendo, Jorge; Vásquez Araque, Neil; Vásquez Correa, Eliana María; Ortega Flórez, Jorge Andrés; Córdoba, Luís Fernando
    Abastract: Introduction. The production of embryos in horses is a technique that provides higher reproduction efficiency for animals with a high genetic value. The access to it and its success are limited, though, due to the difficulties to reach efficient fertilization rates by the use of in vitro conventional fertilization, and given the need of many technical and economic resources for ICSI (intracytoplasmic sperm injection), among other limitations for embryo development in vitro. A fundamental step for embryo production in horses is the in vitro maturation, because it determines the capability an egg has to become an embryo. Several media, fluids and molecules have been evaluated, aiming to improve this process, but an optimal composition of the maturation medium for horse oocytes is not yet known. Objective. To evaluate two components for in vitro maturation: The bovine fetal serum and the horse’s follicular fluid, to understand the physiological reproductive conditions of mares in our environment and what component is better for the maturation as an indicator of the oocyte´s ability to develop itself as an embryo. Materials y Methods. For the in vitro maturation, the bovine fetal serum and the horse´s follicular fluid, they were individually included in a 20% proportion in TCM-199 medium, additionally supplemented with gonadotropins (FSH and LH), antibiotics, glutamine, insulin, transferrin and selenium. Groups of 5 oocytes were incubated during a 36 hours period in controlled environmental conditions, at 39°C, 5% of CO2 and 90% of relative humidity. Results. Higher percentages of maximum expansion of the cluster could be seen for oocytes supple mented with bovine fetal serum (47.5%) compared with those maturated with horse’s follicular fluid (16,2%). No statistic difference was found for the in vitro maturation percentages between treatments. Conclusion. The bovine fetal serum as a supplement for in vitro maturation has a beneficial effect on the cluster expansion of horse’s oocytes.
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    Efecto del etilenglicol sobre la morfología post-desvitrificación de oocitos bovinos inmaduros
    (Corporación Universitaria Lasallista, 2010) Gómez Oquendo, Jorge; Restrepo Betancur, Giovanni; Vásquez Araque, Neil
    Introducción. Almacenar oocitos bovinos inmaduros de forma eficiente permite contar con fuentes casi ilimitadas de recursos genéticos, valiosos para los procesos biotecnológicos de la reproducción y para la investigación. Diversos métodos se han empleado para la criopreservación de este tipo de células, entre de los cuales la vitrificación ha demostrado ser el más exitoso. Sin embargo, los resultados aún son limitados por las bajas tasas de sobrevivencia de los oocitos vitrificados. Objetivo. Determinar entre tres concentraciones del crioprotector etilenglicol cuál previene en mayor proporción las alteraciones sobre la morfología post-desvitrificación de oocitos bovinos inmaduros. Materiales y métodos. Para un protocolo de dos pasos de vitrificación en pajilla abierta estirada (OPS) de oocitos bovinos inmaduros, se evaluaron tres combinaciones en la concentración de etilenglicol: 1, (7.5% y 15%); 2, (10% y 20%) y 3, (20% y 40%). Resultados. Los resultados mostraron que un protocolo que utiliza 20% y 40% de etilenglicol en dos soluciones de vitrificación, produce menores alteraciones en la morfología posdesvitrificación de los oocitos bovinos inmaduros. Conclusiones: La utilización de las concentraciones de 20% y 40% de etilenglicol en un protocolo de vitrificación de dos pasos en OPS tiene un mayor efecto preventivo sobre los daños morfológicos asociados a la vitrificación de oocitos bovinos inmaduros.
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    Estrés oxidativo en el semen equino criopreservado
    (Corporación Universitaria Lasallista, 2012) Restrepo Betancur, Giovanni; Pizarro López, Edison; Rojano, Benjamín Alberto
    The scarce fertility of the cryopreserved equine sperm has significantly limited its use in reproductive biotechnology. Oxidative stress is one of the facts that are related the most to this phenomenon, due to the increase in the levels of species that react to oxygen in the sperm as a result of the thermal shock, the toxicity of cryoprotectors and the alteration in the disposal and the functionality of the endogenous antioxidants during cryopreservation. This revision article analyzes the effect of oxidative stress on the cryopreserved equine sperm´s fertility
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    Evaluación de dos diluyentes para la criopreservación de semen de caballos de la raza criollo colombiano
    (Corporación Universitaria Lasallista, 2014) Restrepo Betancur, Giovanni; Usuga Suarez, Alexandra; Montoya Páez, Juan David; David Celis, Álvaro; Antonio Henao, Andrés
    Introduction. The composition of the extenders for cryopreservation of stallion semen is crucial in cryotolerance and post-thaw fertilizing capacity of sperm cells. Objective. Evaluate two extenders for freezing the semen of Colombian creole stallions. Materials and methods. Semen of four Colombian creole stallions was cryopreserved by fast freezing protocol with Equipro® and Gent® extenders. Evaluation of sperm post-thaw motility was performed by a Sperm Class Analyzer system (SCA®) to examine total motility (TM), progressive motility (PM), velocity curvilinear (VCL), velocity straight line (VSL) and velocity average path (VAP). The sperm vitality (SV) and normal morphology (NM) were assessed by eosin-nigrosin staining; the plasmatic membrane integrity was determined by the hypo-osmotic swelling test (HOS). For statistical evaluation were adjusted generalized linear models (GLM) and the treatments averages were compared by the Tukey test. Associations between variables were assessed by Pearson correlation analysis. Results. Statistical difference (P≤ 0.05) was found for TM with averages of 50.9% ± 19.4% and 42.2% ± 15.1% for Equipro® and Gent®, respectively. Except for VSL no difference was found between the other evaluated parameters. There was a high association between motility parameters, vitality and membrane integrity. Conclusions. Equipro® extender produces superior post-thaw total motility rates than Gent® extender in sperm of Colombian creole stallions.
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    Evaluación de la estimulación ovárica y la calidad de oocitos bovinos obtenidos por aspiración folicular
    (Corporación Universitaria Lasallista, 2017) Giraldo Giraldo, John Jairo; Ordoñez Ramirez, Sebastián; Gómez Oquendo, Jorge; Restrepo Betancur, Giovanni
    Introduction. Ultrasound-guided follicular aspiration (UGFA) coupled with the in-vitro production of embryos is an important alternative for the use of genetic resources of bovine females of high productive potential. However, the reduced quality of oocytes recovered with this technique is one of the aspects with the highest impact on the efficiency to obtain embryos. Materials and methods. This research compared follicular development with the quality of oocytes recovered by UGFA, in bovine females conventionally over-stimulated with FSH or FSH and hCG. Results. A higher quality of oocytes recovered from animals stimulated with FSH and hCG was seen compared to the ones stimulated with FSH only. Conclusions. Inclusion of Hcg in a scheme for the ovarian over-stimulation with FSH of bovine females subject to follicular aspiration becomes a favorable effect on the quality of recovered oocytes.