1,047 research outputs found

    Mitochondrial Thioredoxin-Glutathione Reductase from Larval Taenia crassiceps (Cysticerci)

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    Mitochondrial thioredoxin-glutathione reductase was purified from larval Taenia crassiceps (cysticerci). The preparation showed NADPH-dependent reductase activity with either thioredoxin or GSSG, and was able to perform thiol/disulfide exchange reactions. At 25°C specific activities were 437 ± 27 mU mg−1 and 840 ± 49 mU mg−1 with thioredoxin and GSSG, respectively. Apparent Km values were 0.87 ± 0.04 μM, 41 ± 6 μM and 19 ± 10 μM for thioredoxin, GSSG and NADPH, respectively. Thioredoxin from eukaryotic sources was accepted as substrate. The enzyme reduced H2O2 in a NADPH-dependent manner, although with low catalytic efficiency. In the presence of thioredoxin, mitochondrial TGR showed a thioredoxin peroxidase-like activity. All disulfide reductase activities were inhibited by auranofin, suggesting mTGR is dependent on selenocysteine. The reductase activity with GSSG showed a higher dependence on temperature as compared with the DTNB reductase activity. The variation of the GSSG- and DTNB reductase activities on pH was dependent on the disulfide substrate. Like the cytosolic isoform, mTGR showed a hysteretic kinetic behavior at moderate or high GSSG concentrations, but it was less sensitive to calcium. The enzyme was able to protect glutamine synthetase from oxidative inactivation, suggesting that mTGR is competent to contend with oxidative stress

    Thermal and mechanical properties of recycled poly(Lactic acid)

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    Biodegradable polymers have experienced increased attention in recent years because of their wide range of applications in biomedical, packaging and agriculture fields. PLA, poly(lactic acid), is a linear aliphatic biodegradable thermoplastic polyester, with good mechanical properties, thermal stability, processability and low environmental impact, widely used as an alternative to conventional polymers. PLA products can be recycled after use either by remelting and reprocessing the material, or by hydrolysis to basic lactic acid [1]. The object of this communication is the study of the possible variation in physical properties induced by sub sequent reprocessing cycles of PLA

    Caracterización química y cuantificación del rendimiento de extracción de pigmento en siete accesiones mexicanas de Bixa orellana

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    Achiote (Bixa orellana) is a plant used for obtaining a natural dye rich on carotenoids (mainly bixin and norbixin); it is also the plant species with the highest content of tocotrienols in nature. In the present work, the pigment extraction yield of seven Mexican accessions of Bixa orellana was quantified. Also color parameters and content of tocotrienols, tocopherols, norbixin, bixin, total phenolic compounds and antioxidant capacity were evaluated in the corresponding annatto extracts. The highest percentage of pigment extraction yield was obtained with KOH (4.84%). Accessions 43 (L*= 4.01 ± 0.79, C*= 7.33 ± 1.07, h= 25.76 ± 6.35) and 50 (L*= 3.17 ± 0.64, C*= 6.81 ± 0.53, h= 26.41 ± 4.41) had the lowest color values, meaning these accessions had a darker and redder color. Four accessions showed the highest content of bixin: accession 48 (3.1%), 45 (2.6%) 43 (2.4%) and 47 (2.2%). Accession 50 had showed the highest content of total phenolic compounds and of tocotrienols (T3), mainly the isoform δ-T3 (5.03 ± 0.64 mg g−1 Seed Dry Weight), as well as the highest antioxidant capacity.El achiote (Bixa orellana) es una planta utilizada para obtener un colorante natural rico en carotenoides (principalmente bixina y norbixina); además, es la especie vegetal con el mayor contenido de tocotrienoles. En este trabajo, se determinó el rendimiento de extracción de pigmento de siete accesiones mexicanas de Bixa orellana. También se evaluaron los parámetros de color y el contenido de tocotrienoles, tocoferoles, norbixina, bixina, compuestos fenólicos totales y la capacidad antioxidante en extractos de annato. El mayor porcentaje de rendimiento de extracción de pigmento fue obtenido con KOH (4.847905%). Las accesiones 43 (L*= 4.01 ± 0.79, C*= 7.33 ± 1.07, h= 25.76 ± 6.35) y 50 (L*= 3.17 ± 0.64, C*= 6.81 ± 0.53, h= 26.41 ± 4.41) presentaron los valores más bajos de los párametros de color, lo que significa que estas accesiones tuvieron un color más oscuro y más rojo. Cuatro accesiones mostraron el mayor contenido de bixina: accesión 48 (3.1%), 45 (2.6%) 43 (2.4%) and 47 (2.2%). La accession 50 mostró el mayor contenido de compuestos fenólicos totales y de tocotrienoles (T3), principalmente la isoforma δ-T3 (5.03 ± 0.64 mg g-1 Peso Seco), así como también la mayor capacidad antioxidante.Fil: Raddatz Mota, D.. Universidad Autónoma Metropolitana; MéxicoFil: Pérez Flores, L. J.. Universidad Autónoma Metropolitana; MéxicoFil: Carrari, Fernando Oscar. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Insani, Ester Marina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Asis, Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Mendoza Espinoza, J. A.. Universidad Nacional Autónoma de México; MéxicoFil: Díaz de León Sánchez, F.. Universidad Autónoma Metropolitana; MéxicoFil: Rivera Cabrera, F.. Universidad Autónoma Metropolitana; Méxic

    Hot topics, urgent priorities, and ensuring success for racial/ethnic minority young investigators in academic pediatrics.

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    BackgroundThe number of racial/ethnic minority children will exceed the number of white children in the USA by 2018. Although 38% of Americans are minorities, only 12% of pediatricians, 5% of medical-school faculty, and 3% of medical-school professors are minorities. Furthermore, only 5% of all R01 applications for National Institutes of Health grants are from African-American, Latino, and American Indian investigators. Prompted by the persistent lack of diversity in the pediatric and biomedical research workforces, the Academic Pediatric Association Research in Academic Pediatrics Initiative on Diversity (RAPID) was initiated in 2012. RAPID targets applicants who are members of an underrepresented minority group (URM), disabled, or from a socially, culturally, economically, or educationally disadvantaged background. The program, which consists of both a research project and career and leadership development activities, includes an annual career-development and leadership conference which is open to any resident, fellow, or junior faculty member from an URM, disabled, or disadvantaged background who is interested in a career in academic general pediatrics.MethodsAs part of the annual RAPID conference, a Hot Topic Session is held in which the young investigators spend several hours developing a list of hot topics on the most useful faculty and career-development issues. These hot topics are then posed in the form of six "burning questions" to the RAPID National Advisory Committee (comprised of accomplished, nationally recognized senior investigators who are seasoned mentors), the RAPID Director and Co-Director, and the keynote speaker.Results/conclusionsThe six compelling questions posed by the 10 young investigators-along with the responses of the senior conference leadership-provide a unique resource and "survival guide" for ensuring the academic success and optimal career development of young investigators in academic pediatrics from diverse backgrounds. A rich conversation ensued on the topics addressed, consisting of negotiating for protected research time, career trajectories as academic institutions move away from an emphasis on tenure-track positions, how "non-academic" products fit into career development, racism and discrimination in academic medicine and how to address them, coping with isolation as a minority faculty member, and how best to mentor the next generation of academic physicians

    Dienos conjugados y malondialdehído como indicadores de lipoperoxidación en semen de toros “Carora”

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    Las elevadas temperaturas ambientales incrementan la producción de radicales libres y causan desbalances en los mecanismos antioxidantes. De esta manera se altera el metabolismo celular, lo que repercute en la función reproductiva del macho, con eventuales alteraciones de la capacidad fecundante de los espermatozoides. El objetivo de esta investi­gación fue determinar el grado de lipoperoxidación en semen de toros “Carora” en praderas de la región centroccidental de Venezuela, durante dos años consecutivos en los cuales se registraron temperatura ambiental, humedad y precipitaciones. Se utilizaron 9 toros de 3 a 4 años de edad. El semen se obtuvo con vagina artificial y se preservó a -20°C. Mediante métodos convencionales se obtuvieron los niveles de dienos conjugados (DC) y malondial­dehído (MDA), que fueron analizados estadísticamente mediante el test “t” (p≤0,05). Los niveles de DC fueron de 0,00109 ± 0,00012 nmol/mg de proteínas en el primer año (lluvioso) y 0,00210 ± 0,00030 nmol/mg de proteínas en el segundo año (sequía), siendo la diferencia estadísticamente significativa. En cambio, los niveles seminales de MDA (9,32 ± 2,365 y 7,17 ± 0,510 nmol/mg de proteínas en primer y segundo año respectivamente), no registraron diferencias significativas. El aumento de los niveles de DC (peroxidación en fase inicial) se atribuye a la menor calidad de los pastos por falta de desarrollo debido a insuficientes lluvias del segundo año

    Prospection and identification of traditional-heritage Peruvian grapevine cultivars (Vitis vinifera L.) from Ica and Cañete valleys

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    Interest in ancient and autochthonous cultivars has increased in recent years since they are directly related to the historical and cultural values of a region. Ica and Cañete valleys (Peru) have a long history of grapevine cultivation and the aim of this study was to identify phenotypes corresponding to the most used varieties for the local production of Pisco and wine. The 29 samples were collected in 17 vineyards in the Ica and Cañete valleys, and were analyzed using 20 molecular markers and 5 morphological descriptors according to the OIV. Results showed that the 29 collected samples corresponded to 11 genotypes: seven traditional cultivars and four unknown genotypes not registered previously. The known cultivars were 'Muscat of Alexandria', 'Listán Prieto', 'Quebranta', 'Moscatel Rosado', 'Pedro Giménez', 'Muscat Hamburg' and 'Palomino Fino'. The four not registered genotypes are locally known as 'Mollar de Ica', 'Moscatel Rosada de Cañete', 'Prieta Mollar' and 'Torontel'. All of them correspond to offspring of traditional-heritage Peruvian cultivars. We also found a phenotypic variation of 'Listán Prieto' with muscat flavor and identified phenotypic berry color variations in 'Quebranta'. This study increases the knowledge of traditional Peruvian grape varieties and highlight the genetic variability preserved in the traditional vineyards of local producers
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