Estudio teórico y experimental del sistema 9 Be + 51 V y sistemas similares

En este trabajo de tesis se presenta el estudio sistemático de los sistemas 7Li + 51V, 9Be + 51V y 8B + 58Ni. Para los sistemas ( 7Li, 9 Be) + 51V se midieron las secciones eficaces de fusión a energías cercanas a la barrera Coulombiana (EB,lab=11.75 y 16.16 MeV, respectivamente) empleando la técnica de rayos γ. El experimento para medir la fusión se llevó a cabo en el Laboratorio del Acelerador Tan- dem, del Instituto Nacional de Investigaciones Nucleares (ININ), siendo éstas las primeras mediciones realizadas para estos proyectiles a las energías consideradas. De forma simultánea, se hizo el análisis de los posibles núcleos residuales usando los códigos computacionales de fusión-evaporación PACE2, LILITA y CASCADE. Los resultados obtenidos fueron comparados con los datos experimentales me- didos. De forma preliminar, para el sistema 7Li + 51V, se hicieron cálculos usando la teoría de canales acoplados de reacción para estimar la contribución de la sección eficaz de transferencia de un protón a la producción del núcleo residual 52Cr. Para el sistema 8B + 58Ni, se hizo un análisis teórico de canales acoplados con el continuo discretizado y canales acoplados de reacción para estudiar los procesos de rompimiento y de transfe- rencia de un protón, 58Ni(8B,7Be)59Cu, a energías alrededor de la barrera Coulombiana (EB,lab=22.95 MeV). Para calcular las secciones eficaces correspondientes se usó un potencial de Modelo Óptico se- mimicroscópico, el cual combina un potencial real de doble convolución, un potencial de polarización y un potencial imaginario tipo Woods-Saxon. A partir de la comparación de nuestros cálculos con datos experimentales se determinaron los factores espectroscópicos Sexpt y astrofísicos S17(0) del protón en la interacción 8B → 7Be+p

Involvement of the nitric oxide, fos protein and brain stem in the retention of brain glucose during hypoxia [Participación del óxido nítrico, proteína fos y el tallo cerebral en la retención de glucosa encefálica durante la hipoxia]

It has been said that the nucleus tractus solitarii (NTS), one structure of the brain stem and path of apherences of chemoreceptors of carotid sinus-body, is involved in the increased glucose retention by the brain in case of hypoxia. It is likely that nitric oxide and Fos protein also take part in this response. This paper analyzes the role of nitric oxide in the NTS on the change of glucose retention by the brain and the expression of inmunoreactive protein Fos (ir-Fos) in rats in vivo. The injection of a NO donor such as sodium nitroprusiate in the NTS four minutes before the stimulation of carotid sinus-body chemoreceptors decreased glucose retention by the brain but increased the expression of ir-Fos in a higher number of neurons in NTS with respect to control group rats which only received artificial cerebrospinal fluid before the stimulation. In contrast, the use of a selective NO inhibitor such as NO-nitro-L-arginine methyl ester (L-NAME) in the NTS four minutes before the stimulation of the chemoreceptors with NaCN, increased the glucose retention by the brain but reduced the number of neurons with ir-Fos expression when compared with the control group or the sodium nitroprusiate injection. The immunohistochemical detection of ir-Fos expression in the brain stem cells indicated that stimulation of carotid sinus-body chemoreceptors activated NO-dependent paths in the NTS to regulate glucose retention by the brain. The study of this cell population in the NTS will be important to define its characterization

Involvement of the nitric oxide, fos protein and brain stem in the retention of brain glucose during hypoxia [Participación del óxido nítrico, proteína fos y el tallo cerebral en la retención de glucosa encefálica durante la hipoxia]

It has been said that the nucleus tractus solitarii (NTS), one structure of the brain stem and path of apherences of chemoreceptors of carotid sinus-body, is involved in the increased glucose retention by the brain in case of hypoxia. It is likely that nitric oxide and Fos protein also take part in this response. This paper analyzes the role of nitric oxide in the NTS on the change of glucose retention by the brain and the expression of inmunoreactive protein Fos (ir-Fos) in rats in vivo. The injection of a NO donor such as sodium nitroprusiate in the NTS four minutes before the stimulation of carotid sinus-body chemoreceptors decreased glucose retention by the brain but increased the expression of ir-Fos in a higher number of neurons in NTS with respect to control group rats which only received artificial cerebrospinal fluid before the stimulation. In contrast, the use of a selective NO inhibitor such as NO-nitro-L-arginine methyl ester (L-NAME) in the NTS four minutes before the stimulation of the chemoreceptors with NaCN, increased the glucose retention by the brain but reduced the number of neurons with ir-Fos expression when compared with the control group or the sodium nitroprusiate injection. The immunohistochemical detection of ir-Fos expression in the brain stem cells indicated that stimulation of carotid sinus-body chemoreceptors activated NO-dependent paths in the NTS to regulate glucose retention by the brain. The study of this cell population in the NTS will be important to define its characterization

A new bilayer chitosan scaffolding as a dural substitute: Experimental evaluation

Objective: To evaluate whether bilayer chitosan scaffolding (BChS) can provide a watertight dural closure and permit regeneration by fibroblasts in an experimental in vivo model. Methods: In the in vitro phase, BChS was elaborated and the following characteristics were evaluated: pore size, thickness, water absorption capacity, tensile strength, strain, and toughness. In the second in vivo phase, 27 durectomized New Zealand rabbits were randomly assigned into three duraplasty groups with autologous dura, collagen matrix (CM), or BChS. In all groups, fluid leakage pressure was measured at 10, 21, or 180 days. Histology response to regeneration was evaluated through hematoxylin and eosin stain. Results: BChS was standardized to obtain bilayer scaffoldings with a nonporous layer and a porous layer. The pore size was 10 ?m, total thickness was 400 ?m, strain was 57.8%, and tensile strength was 5.5 gr/mm 2. The physical characteristics of BChS allowed dural closure without cerebrospinal fluid (CSF) leak. There were no differences in fluid leakage pressures between the BChS, dura, and CM groups. Histologic analysis showed fibroblast migration with adequate dural regeneration. Conclusions: BChS is an ideal alternative for a watertight dural closure because it can be sutured, and it induces organized regeneration with fibroblasts without evidence of fibrosis. � 2012 Elsevier Inc. All rights reserved

Особенности силовой подготовки студентов 1 курса БГУИР : метод. рекомендации для преподавателей и студентов

В данных рекомендациях в краткой форме изложены основные методические принципы силовой подготовки студентов 1 курса университета. Предложены примерные комплексы упражнений для юношей и девушек, направленные на развитие силовых качеств основных мышечных групп. Издание предназначено для преподавателей и студентов

Ultrastructural analysis of guided nerve regeneration using progesterone- and pregnenolone-loaded chitosan prostheses

Recently, numerous guide chambers for the treatment of injured nerves made up of different biomaterials have been designed, capable of hosting living cells or carrying neurotrophic or neuroactive substances to be directly released to the injured tissue. In this study, chitosan prostheses containing neurosteroids (progesterone and pregnenolone) were used for bridging a 10-mm gap in the rabbit facial nerve. Gas chromatography was used to quantify neurosteroid content in the prostheses prior to and after subcutaneous implantation at different periods of up to 60 days. The regeneration of the nerve fibers were evaluated at 15 and 45 days after axotomy by means of ultrastructural morphometric analysis. Different nerve fibers regenerative patterns were seen depending the groups studied and the analyzed stages. At 15 days after axotomy, the newly regenerating tissue revealed Schwann cells holding nonmyelinated nerve fiber bundles in an incipient and organized regenerative pattern. At 45 days, the regenerating tissue showed myelinated nerve fibers of different sizes, shapes, and myelin sheath thickness. Although the regeneration of the nerve fibers under neurosteroid treatment showed statistically significant differences in comparison with vehicle regenerated tissue, progesterone-loaded chitosan prostheses produced the best guided nerve regeneration response. These findings indicate that chitosan prostheses allowed regeneration of nerve fibers in their lumen, and when containing neurosteroids produced a faster guided nerve regeneration acting as a long-lasting release delivery vehicle. © 2005 Wiley Periodicals, Inc

Unpolarized states and hidden polarization

Recently, numerous guide chambers for the treatment of injured nerves made up of different biomaterials have been designed, capable of hosting living cells or carrying neurotrophic or neuroactive substances to be directly released to the injured tissue. In this study, chitosan prostheses containing neurosteroids (progesterone and pregnenolone) were used for bridging a 10-mm gap in the rabbit facial nerve. Gas chromatography was used to quantify neurosteroid content in the prostheses prior to and after subcutaneous implantation at different periods of up to 60 days. The regeneration of the nerve fibers were evaluated at 15 and 45 days after axotomy by means of ultrastructural morphometric analysis. Different nerve fibers regenerative patterns were seen depending the groups studied and the analyzed stages. At 15 days after axotomy, the newly regenerating tissue revealed Schwann cells holding nonmyelinated nerve fiber bundles in an incipient and organized regenerative pattern. At 45 days, the regenerating tissue showed myelinated nerve fibers of different sizes, shapes, and myelin sheath thickness. Although the regeneration of the nerve fibers under neurosteroid treatment showed statistically significant differences in comparison with vehicle regenerated tissue, progesterone-loaded chitosan prostheses produced the best guided nerve regeneration response. These findings indicate that chitosan prostheses allowed regeneration of nerve fibers in their lumen, and when containing neurosteroids produced a faster guided nerve regeneration acting as a long-lasting release delivery vehicle. " 2005 Wiley Periodicals, Inc.",,,,,,"10.1002/jbm.b.30243",,,"http://hdl.handle.net/20.500.12104/45534","http://www.scopus.com/inward/record.url?eid=2-s2.0-21444441396&partnerID=40&md5=d335b886a33765afdc8b08f3120c9f99",,,,,,"1",,"Journal of Biomedical Materials Research - Part B Applied Biomaterials",,"58

Comparación de los niveles de igg en cerdos pelón Mexicano y yorkshire x landrace en diferentes etapas de maduración inmunológica

By means of immunoglobulin G (IgG) levels, serum immunological response was compared between the Mexican Pelón (PM) and the Yorkshire x Landrace (YL) commercials, in four different stages of immunological maturation (28, 32 , 45 and 60 days of age), comparing between the two lines (regardless of sex), between males and females of the two lines and between genders of the same line. Twelve 12 pigs of the breed PM and 12 YL (6 females and 6 males) were analyzed. IgG levels in the PM were higher in the last three stages: post-weaning (P <0.05) post-vaccination (P <0.01) and immunological maturation (P <0.01). Between males of the two lines no significant differences were found although the levels in the PM were higher in all stages than in the YL. The IgG levels between the females of both lines were higher in the PM than in the CCO with significant differences in the second and third stages of (P <0.05), whereas in the first stage only the IgG levels in YL females were higher (P <0.05). In YL IgG levels were higher in females in the first stage (P <0.05). It could be inferred that the immune response of the Mexican Pelon piglet tends to be greater than that of the commercial pig F1 of the Yorkshire x Landrace crossing, perhaps due to its immunological memory, rusticity, and to its better adaptation to the environment. Thus, it is possible that the Mexican Pelón pig may be a reservoir of genetic determinants of natural resistance to different diseases as suggested.Por medio de los niveles de inmunoglobulina G (IgG), en suero se comparó la capacidad de respuesta inmunológica entre los cerdos Pelón Mexicano (PM) y los comerciales Yorkshire x Landrace (YL), en cuatro etapas diferentes de maduración inmunológica (28, 32, 45 y 60 días de edad), realizando la comparación entre las dos líneas (sin importar el sexo), entre machos y hembras de las dos líneas y entre sexos de la misma línea. Se analizaron 12 lechones de la raza PM y 12 YL (6 hembras y 6 machos). Los niveles de IgG en los PM fueron mayores en las tres últimas etapas: post-destete (P<0.05) post-vacunación (P<0.01) y maduración inmunológica (P<0.01). Entre machos de las dos líneas no se encontraron diferencias significativas aunque los niveles en los PM fueron mayores en todas las etapas que en los YL. Los niveles de IgG entre las hembras de ambas líneas fueron mayores en los PM que en los CCO con diferencias significativas en la segunda y tercera etapa de (P<0.05) mientras que sólo en la primera etapa los niveles de IgG en hembras YL fueron mayores (P<0.05). En los YL los niveles de IgG fueron mayores en las hembras en la primera etapa (P<0.05). Se pudiera inferir que la respuesta inmune del cerdito Pelón Mexicano tiende a ser mayor que la del cerdo comercial F1 del cruce Yorkshire x Landrace, debido quizá a su memoria inmunológica, rusticidad, y a su mejor adaptación al medio. Así, es posible que el cerdo Pelón Mexicano pueda ser reservorio de determinantes genéticos de resistencia natural a diferentes enfermedades como se ha sugerido