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Search Results: 1 - 10 of 224236 matches for " Luis Carrión-Rivera "
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Mutual Coupling Effects Analysis in a Cross-Rhombic Antenna Array
Jorge Sosa-Pedroza,Luis Carrión-Rivera,Sergio Pe a-Ruiz,Fabiola Martínez-Zu iga
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/817105
Abstract: We present an analysis of mutual coupling effects on radiation pattern and individual coupling in a conformal array of cross rhombic antennas. Analysis is made using both full-wave simulation and numerical approaches implemented in Matlab. The array consists of a truncated hexagonal pyramid, with a cross rhombic antenna in each pyramidal face, including the one on the top, having a 7-antennas-array. Results of radiation pattern and S11 parameters are presented, showing mutual coupling effects among the elements.
América Latina, una región en desarrollo marcada por la mala distribución de la riqueza
Aragón-Rivera,Efraim;
Papel Politico , 2010,
Abstract: this article defines the concepts of including, excluding, marginality, marginalization and vulnerability inside the latin-american region, which with the flow of the society carries from its capitalist origins unequal forms in the structural functioning of the production system, causing the inequality in the income and wealth distribution, causes of the endemic poverty that suffers the region and that only with the achievement of vigorous public social policies can diminish.
Efecto de una intervención educativa en la calidad de vida del paciente hipertenso
Barrón-Rivera,Adalberto Jorge; Torreblanca-Roldán,Federico Luis; Sánchez-Casanova,Landy Isabel; Martínez-Beltrán,Miguel;
Salud Pública de México , 1998, DOI: 10.1590/S0036-36341998000600007
Abstract: objective. to evaluate the effect of an educational program on the quality of life of the hypertense patient. material and methods. a randomized clinical trial was performed on 150 adult hypertense patients who were divided into 2 groups. the experimental group received a short educational program on hypertension and the effects on the patients′ life style, specifically concerning their control of the disease. the control group did not receive the educational program. quality of life of both groups was determined by an analogous visual scale, before and 6 months after the educational program. data were analyzed by the paired t- and wilcoxon tests. results. the degree of improvement with respect to physical strength and emotional condition differed between groups (p<0.05). in the areas of thought capacity, social participation, perceived quality of life and sexual function only the experimental group showed changes (p<0.05). conclusions. an educational program is effective to modify the quality of life of the hypertense patient.
Efecto de una intervención educativa en la calidad de vida del paciente hipertenso
Barrón-Rivera Adalberto Jorge,Torreblanca-Roldán Federico Luis,Sánchez-Casanova Landy Isabel,Martínez-Beltrán Miguel
Salud Pública de México , 1998,
Abstract: Objetivo. Evaluar el efecto de una intervención educativa sobre la calidad de vida del paciente hipertenso. Material y métodos. Se estudiaron 150 adultos hipertensos en un primer nivel de atención mediante un ensayo clínico aleatorizado a dos grupos. El grupo experimental fue objeto de una intervención educativa sobre hipertensión y la repercusión del estilo de vida en el control de tal enfermedad. El grupo testigo no recibió intervención. En ambos grupos se determinó la calidad de vida mediante una escala análoga visual, antes y seis meses después de la intervención educativa. Los datos se analizaron mediante las pruebas t-pareada y Wilcoxon. Resultados. El grado de mejoría, en relación con la fuerza física y el estado anímico, difirió entre grupos (p< 0.05); en las áreas correspondientes a la capacidad de pensamiento, la convivencia social-familiar, la percepción de calidad de vida y el funcionamiento sexual, sólo el grupo experimental mostró cambios (p< 0.05). Conclusiones. La intervención educativa es efectiva para modificar la calidad de vida del paciente hipertenso.
Creatine supplementation upregulates excitation-contraction coupling in C2C12 myotubes
Aida Calderón-Rivera, Ana Victoria Vega, Guillermo Avila
Journal of Receptor, Ligand and Channel Research , 2010, DOI: http://dx.doi.org/10.2147/JRLCR.S6595
Abstract: eatine supplementation upregulates excitation-contraction coupling in C2C12 myotubes Original Research (3775) Total Article Views Authors: Aida Calderón-Rivera, Ana Victoria Vega, Guillermo Avila Published Date May 2010 Volume 2010:3 Pages 63 - 71 DOI: http://dx.doi.org/10.2147/JRLCR.S6595 Aida Calderón-Rivera, Ana Victoria Vega, Guillermo Avila Department of Biochemistry, Cinvestav-IPN, Mexico City, Mexico Abstract: The main goal of this work was to investigate whether creatine (Cr) might be able to regulate skeletal muscle excitation-contraction (EC) coupling. Myotubes from a C2C12 cell line were exposed to Cr (25 mM, 2–4 hours). Subsequently, the activity of L-type Ca2+ channels and voltage-gated Ca2+ release (VGCR) were investigated using the whole-cell patch-clamp technique. Cr upregulated VGCR by 2.4-fold, in the absence of major alterations in L-type Ca2+ channel activity, the extent of caffeine-induced sarcoplasmic reticulum Ca2+ release, or the termination kinetics of Ca2+ transients. Thus, stimulation of VGCR cannot be explained by upregulation of the activity of either L-type Ca2+ channels or sarcoplasmic reticulum Ca2+-ATPase. We also investigated possible long-term regulation of L-type Ca2+ channels by Cr. However, chronic treatment with Cr (2–4 days) affected neither the density of ICaL nor the corresponding voltagedependence of activation. The later result was obtained in the face of a 1.7-fold stimulation of myogenesis. Therefore, it cannot be explained by possible desensitization of Cr metabolism. These data could suggest that the functional expression of L-type Ca2+ channels is not affected by prior acute stimulation of VGCR. Previous work has shown that Cr supplementation enhances muscle strength. Thus, it will be interesting to investigate whether this effect can be at least partially explained by acute stimulation of VGCR.
Creatine supplementation upregulates excitation-contraction coupling in C2C12 myotubes
Aida Calderón-Rivera,Ana Victoria Vega,Guillermo Avila
Journal of Receptor, Ligand and Channel Research , 2010,
Abstract: Aida Calderón-Rivera, Ana Victoria Vega, Guillermo AvilaDepartment of Biochemistry, Cinvestav-IPN, Mexico City, MexicoAbstract: The main goal of this work was to investigate whether creatine (Cr) might be able to regulate skeletal muscle excitation-contraction (EC) coupling. Myotubes from a C2C12 cell line were exposed to Cr (25 mM, 2–4 hours). Subsequently, the activity of L-type Ca2+ channels and voltage-gated Ca2+ release (VGCR) were investigated using the whole-cell patch-clamp technique. Cr upregulated VGCR by 2.4-fold, in the absence of major alterations in L-type Ca2+ channel activity, the extent of caffeine-induced sarcoplasmic reticulum Ca2+ release, or the termination kinetics of Ca2+ transients. Thus, stimulation of VGCR cannot be explained by upregulation of the activity of either L-type Ca2+ channels or sarcoplasmic reticulum Ca2+-ATPase. We also investigated possible long-term regulation of L-type Ca2+ channels by Cr. However, chronic treatment with Cr (2–4 days) affected neither the density of ICaL nor the corresponding voltagedependence of activation. The later result was obtained in the face of a 1.7-fold stimulation of myogenesis. Therefore, it cannot be explained by possible desensitization of Cr metabolism. These data could suggest that the functional expression of L-type Ca2+ channels is not affected by prior acute stimulation of VGCR. Previous work has shown that Cr supplementation enhances muscle strength. Thus, it will be interesting to investigate whether this effect can be at least partially explained by acute stimulation of VGCR.Keywords: L-type calcium channel, ryanodine receptor, intracellular calcium
Obtención de fibras policristalinas de b-Ca3(PO4)2 para su empleo como material de relleno en procesos de reparación ósea
Franco-Vázquez, J.,Souto-Serante, A.,Rey-Rodríguez, P.,Guitián-Rivera, F.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2007,
Abstract: b-TCP is a calcium phosphate ceramic widely employed by orthopaedic restorative surgery as a filler material in bone healing processes, due to its great osteoconductive capacity and great resorption rates. This material is available in several forms such as powders, dense and porous blocks, etc, depending on the pathology and the osseous defect to be treated. As an alternative to the b-TCP forms already available in the market, this work describes how to produce polycrystalline fibres by extruding plastic mixtures prepared with b-TCP powders, methyl cellulose (MC) and water. The rheology of the mixtures was studied versus time and frequency. The obtained fibres have different sizes and characteristics upon to the composition and rheology of the mixtures. The obtained diameters are between 150 μm and 350 μm. Finally, it has been prepared biphasic composites b-TCP/Hidroxylapatite (HA) with controlled microstructure, by employing the obtained fibres. El b-Ca3(PO4)2 (b-TCP) es un fosfato cálcico ampliamente empleado como material de relleno por la cirugía ortopédico restauradora en procesos de curación ósea, debido a su capacidad osteoconductora y alta tasa de biorreabsorción. Se emplea con distintas formas, tales como granulados, piezas compactas, piezas porosas, etc, dependiendo de la patología y el tipo de defecto óseo a tratar. Como alternativa a las formas ya existentes en el mercado, en el presente trabajo se obtuvieron fibras policristalinas de b-TCP por extrusión de masas plásticas preparadas a partir de polvo de b-TCP y metilcelulosa (MC) en agua. Se estudió la reología de las pastas y su comportamiento frente al esfuerzo y a la temperatura. Las fibras presentan distintos grosores, y características, que se obtienen variando el diámetro de las boquillas, la composición y la reología de las pastas. Los diámetros obtenidos van desde 350 μm a 150 μm. Finalmente se obtuvieron composites bifásicos b-TCP-Hidroxiapatito con microestructura controlada, utilizando las fibras de b-TCP como fase dispersa.
Stimulation of the Protective Response to Actinomycetoma by Nocardia brasiliensis in Mice Treated with Candida albicans Antigens  [PDF]
Alejandro Palma-Ramos, Violeta Karen Espinosa-Antunez, Laura Estela Castrillón-Rivera, Oralia Nájera-Medina, María Elisa Vega-Memije, Roberto Arenas-Guzmán, María Elisa Drago-Serrano, Teresita Sainz-Espu?es
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.46036
Abstract:

Actinomycetoma is a chronic subcutaneous lesion caused by the pathogenic bacterium Nocardia (N.) brasiliensis. Yeast antigens of Candida (C.) albicans increase the interferon (IFN)-γ and TCD4+ cells levels that enhance the phagocytic killing of N. brasiliensis, able to survive inside phagocytes and to grow in clustered colonies that form grains. The aim of this work was to test the effect of a crude protein extract of C. albicans on the levels of IFN-γ producing TCD4+ cells and on the outcome of actinomycetoma lesion. Five BALB/c mice with N. brasiliensis infection at left hind footpad were treated four times every other day with C. albicans crude protein extract (CPE). Five uninfected mice treated with CPE or infected mice treated with sterile phosphate-saline buffer were included as positive and negative control groups, respectively. Footpad thickness was recorded in all groups. Once the treatments were finished, single cell suspensions from blood and spleen were prepared for assessing the amount (%) of IFN-

Detection of β-Glucuronidase Activity within Actinomadura madurae Grains of Human Actinomycetoma  [PDF]
Alejandro Palma-Ramos, Samantha Reyes-Mayén, Laura Estela Castrillón-Rivera, Silvia Elena Fernández-López, Carmen Padilla-Desgarennes, María Elisa Vega-Memije, Roberto Arenas-Guzmán, María Elisa Drago-Serrano, Teresita Sainz-Espu?es
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.46038
Abstract:

Actinomycetoma syndrome by Actinomadura (A.) madurae is characterized by a subcutaneous chronic lesion that affects fascia, muscle and bone. A. madurae produces colonies that form grains of less than 1 mm in diameter. Grains are surrounded and infiltrated by neutrophils involved in the grain disruption by enzymes like β-glucuronidase released after the neutrophil degranulation. The aim of this work was to evaluate the polysaccharide degradation of grains treated with β-glucuronidase and to detect the presence and activity of β-glucuronidase within the A. madurae grains. Actinomadura madura grains from patients infected were processed to quantify the total content of polysaccharide with the phenol-sulfuric acid reaction. Grains were treated with β-glucuronidase at different conditions to evaluate the optimal polysaccharide degradation. Grains were analyzed to detect the enzyme by using anti-human β-glucuronidase antibody while enzymatic activity was assessed by evaluating the release of reduced sugars and by in situ enzymatic activity. Optimal degradation of polysaccharide in the grains treated with β-glucuronidase was found with 300 units/ml of enzyme and 24 hr of incubation at 37°

Gasterópodos asociados al alga calcárea Halimeda opuntia (Udoteaceae) en Puerto Rico
García-Ríos,Cedar I; Soto-Santiago,Francisco J; Colón-Rivera,Ricardo J; Medina-Hernández,Javier R;
Revista de Biología Tropical , 2008,
Abstract: gastropods associated with the calcareous alga halimeda opuntia (udoteaceae) in puerto rico. gastropod communities associated with the calcareous green alga halimeda opuntia are described and compared for two puerto rico coral reefs: one in the northeast with front tradewinds (windward zone) and one in the southwest (leeward zone). we analyzed the content of 21 lots (2432 g) of h. opuntia from leeward zone and 15 lots (2448 g) from the windward zone. in total we recovered 526 gastropods (prosobranchs) classified in 54 taxa. thirteen species of gastropods represented 79.6% of the community. differences between species richness and mean density values were not significant (p>0.100). forty species were identified from leeward and thirty one (31) species from windward. gastropod mean density was 13.9 /100g of algae in leeward and 7.6/100g in windward. significant differences were found for the simpson diversity index (0.91 in the leeward and 0.82 in the windward community; t=3.44, α=0.005). we found no correlation between the weight of the algae and the frequency of the gastropods (r2=0.0893 in leeward, 0.0249 windward and 0.0923 for both). the relationship between species composition in lots of windward and leeward study sites was explored via polar ordination and no segregation was found. when compared, the gastropod communities found in h. opuntia collected in coral reefs in puerto rico were more similar within them than any other communities found in other genera of seaweed and in other environments. our results agree with the hypothesis that h. opuntia offers the interstitial community a protected microhabitat from water movement impact. h. opuntia creates more homogenous conditions than those of the habitat where we found the algae. rev. biol. trop. 56 (4): 1665-1675. epub 2008 december 12.
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