Caracterização de célula progenitora hepática no cultivo celular de fígado de feto canino

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bioestimulação de célula-tronco mesenquimal de rato sob ação da luz contínua e pulsátil de 630 nm utilizando LED

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desenvolvimento de conjunto membrana-eletrodos para célula a combustível de metanol direto passiva

Direct methanol fuel cells (DMFCs) without external pumps or other ancillary devices for fuel and oxidant supply are known as passive DMFCs and are potential candidates to replace lithium-ion batteries in powering portable electronic devices. This paper presents the results obtained from a membrane electrode assembly (MEA) specifically designed for passive DMFCs. Appropriated electrocatalysts were prepared and the effect of their loadings was investigated. Two types of gas diffusion layers (GDL) were also tested. The influence of the methanol concentration was analyzed in each case. The best MEA performance presented a maximum power density of 11.94 mW cm^-2.

Bioestimulação de célula-tronco mesenquimal de rato sob ação da luz contínua e pulsátil de 630 nm utilizando LED

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Regulación del ciclo de la fosfatidilcolina en célula granulosa ovárica

Premio Extraordinario, Área de Ciencias de la Salud

AN INVESTIGATION INTO THE MOLECULAR MECHANISMS OF ANDROGEN ACTION IN THE SERTOLI CELL

Steroid hormones regulate target cell function via quantitative and qualitative changes in RNA and protein synthesis. In the testis, androgens are known to play an important role in the regulation of spermatogenesis. The Sertoli cell (SC), whose function is thought to be supportive to the developing germ cell, has been implicated as an androgen target cell. Although cytoplasmic androgen receptors and chromatin acceptor sites for androgen-receptor complexes have been found in SC, effects on RNA synthesis have not previously been demonstrated. In this study, SC RNA synthetic activity was characterized and the effect of testosterone on SC nuclear transcriptional activity in vitro assessed. SC exhibited two fold increases in RNA and ribonucleotide pool concentrations during sexual maturation. These changes appeared to correlate with a previously observed increase in protein concentration per cell over an age span of 15-60 days. Following incubation with ('3)H-uridine, SC from older animals incorporated more label into RNA than SC from younger animals. Since the relative concentration of cytidine nucleotides was higher in SC from older rats, the age-related increase in tritium incorporation may reflect an associated increase in incorporation of ('3)H-CMP into RNA. Alternatively, the enhanced labeling may be the result of either a change in the base composition of the RNA resulting in a higher proportion of CMP and UMP in the RNA, or compartmentalization of the nucleotide pools. The physiologic consequences of these maturational alterations of nucleotide pools remains to be elucidated. RNA polymerase activities were characterized in intact nuclei obtained from cultured rat SC. (alpha)-Amanitin resistant RNA polymerase I+III activity was identical when measured in low or high ionic strength (0.05 M or 0.25 M ammonium sulfate (AS)) in the presence of MnCl(,2) or MgCl(,2), with a divalent cation optimum of 1.6 mM. RNA polymerase II was most active in 0.25 M AS and 1.6 mM MnCl(,2). The apparent Km of RNA polymerase II for UTP was 0.016 mM in 0.05 M AS and 0.037 mM in 0.25 M AS. The apparent Km values for total polymerase activity was 0.008 mM and 0.036 mM at low and high ionic strenghts, respectively. These data indicate that Sertoli cell RNA polymerase activities have catalytic properties characteristic of eukaryotic polymerase activities in general. In the presence of 21 (mu)M testosterone, RNA polymerase II activity increased two fold at 15 minutes, then declined but was still elevated over control values six hours after androgen addition. Polymerase I+III activity was not greatly affected by testosterone. The stimulation of polymerase II measured at 15 minutes was dose-dependent, with a maximum at 0.53 nM and no further stimulation up to 10('-5) M (ED(,50) = 0.25 nM testosterone), and was androgen specific. The results of preliminary RNA isolation and characterization experiments suggested that the synthesis of several species of RNA was enhanced by testosterone administration. These findings have great potential importance since they represent the first demonstration of a direct effect of androgens on the transcriptional process in the Sertoli cell. Furthermore, the results of these studies constitute further evidence that the Sertoli cell is a target for androgen action in the testis. ^

La imagen de célula : El caso de las fibras musculares representadas por alumnos universitarios

En las ciencias morfológicas las imágenes son indispensables para el desarrollo del conocimiento conceptual y operan como elementos significantes. En el caso de la enseñanza de la histología, las representaciones gráficas tienen tanta relevancia como las descripciones escritas y pueden emplearse para evaluar la comprensión de los distintos temas. El presente trabajo se propone analizar las representaciones de las células musculares humanas (lisas y estriadas) como parte de un examen parcial de un grupo de alumnos universitarios. Se clasifican las respuestas en tres categorías respecto de la naturaleza del obstáculo encontrado (si concierne al nivel de organización, al concepto del tipo de célula, o a inconvenientes en la noción de las dimensiones) y se plantean explicaciones posibles para los resultados obtenidos

La imagen de célula : El caso de las fibras musculares representadas por alumnos universitarios

En las ciencias morfológicas las imágenes son indispensables para el desarrollo del conocimiento conceptual y operan como elementos significantes. En el caso de la enseñanza de la histología, las representaciones gráficas tienen tanta relevancia como las descripciones escritas y pueden emplearse para evaluar la comprensión de los distintos temas. El presente trabajo se propone analizar las representaciones de las células musculares humanas (lisas y estriadas) como parte de un examen parcial de un grupo de alumnos universitarios. Se clasifican las respuestas en tres categorías respecto de la naturaleza del obstáculo encontrado (si concierne al nivel de organización, al concepto del tipo de célula, o a inconvenientes en la noción de las dimensiones) y se plantean explicaciones posibles para los resultados obtenidos

La imagen de célula : El caso de las fibras musculares representadas por alumnos universitarios

En las ciencias morfológicas las imágenes son indispensables para el desarrollo del conocimiento conceptual y operan como elementos significantes. En el caso de la enseñanza de la histología, las representaciones gráficas tienen tanta relevancia como las descripciones escritas y pueden emplearse para evaluar la comprensión de los distintos temas. El presente trabajo se propone analizar las representaciones de las células musculares humanas (lisas y estriadas) como parte de un examen parcial de un grupo de alumnos universitarios. Se clasifican las respuestas en tres categorías respecto de la naturaleza del obstáculo encontrado (si concierne al nivel de organización, al concepto del tipo de célula, o a inconvenientes en la noción de las dimensiones) y se plantean explicaciones posibles para los resultados obtenidos