Avaliação da capacidade de absorção de energia de betões reforçados com fibras de aço

O betão reforçado com fibras de aço (BRFA) é um material de matriz cimentícia a cuja composição é adicionada determinada percentagem de fibras discretas. A capacidade de absorção de energia é a principal propriedade beneficiada pelo reforço das fibras. Neste trabalho descreve-se os ensaios de flexão efectuados em vigas de BRFA com entalhe a meio vão e submetidas a três pontos de carga. Os ensaios foram efectuados sob controlo de deslocamento. Realizaram-se ensaios com séries de provetes reforçados com 30, 60 e 90 kg/m3 de fibras de aço. Os resultados obtidos são apresentados e discutidos. É proposto um conceito com potencial utilização no dimensionamento de peças de BRFA

Lipid phosphate phosphatase-1 regulates lysophosphatidic acid- and platelet-derived-growth-factor-induced cell migration

LPPs (lipid phosphate phosphatases) are members of a family of enzymes that catalyse the dephosphorylation of lipid phosphates. The only known form of regulation of this family of enzymes is via de novo expression of LPP isoforms in response to growth factors. In this respect, we evaluated the effect of moderate increases in the expression of recombinant LPP1 on signal transduction by both G-protein-coupled receptors and receptor tyrosine kinases. We present evidence for a novel role of LPP1 in reducing PDGF (platelet-derived growth factor)- and lysophosphatidic acid-induced migration of embryonic fibroblasts. We demonstrate that the overexpression of LPP1 inhibits cell migration by reducing the PDGF-induced activation of p42/p44 MAPK (mitogen-activated protein kinase). This appears to occur via a mechanism that involves the LPP1-induced down-regulation of typical PKC (protein kinase C) isoform(s), which are normally required for PDGF-induced activation of p42/p44 MAPK and migration. In this regard, DAG (diacylglycerol) levels are high and sustained in cells overexpressing LPP1, suggesting a dynamic interconversion of phosphatidic acid into DAG by LPP1. This may account for the effects of LPP1 on cell migration, as sustained DAG is known to down-regulate PKC isoforms in cells. Therefore the physiological changes in the expression levels of LPP1 might represent a heterologous desensitization mechanism for attenuating PKC-mediated signalling and regulation of cell migration

The Expression and Localization of N-Myc Downstream-Regulated Gene 1 in Human Trophoblasts

The protein N-Myc downstream-regulated gene 1 (NDRG1) is implicated in the regulation of cell proliferation, differentiation, and cellular stress response. NDRG1 is expressed in primary human trophoblasts, where it promotes cell viability and resistance to hypoxic injury. The mechanism of action of NDRG1 remains unknown. To gain further insight into the intracellular action of NDRG1, we analyzed the expression pattern and cellular localization of endogenous NDRG1 and transfected Myc-tagged NDRG1 in human trophoblasts exposed to diverse injuries. In standard conditions, NDRG1 was diffusely expressed in the cytoplasm at a low level. Hypoxia or the hypoxia mimetic cobalt chloride, but not serum deprivation, ultraviolet (UV) light, or ionizing radiation, induced the expression of NDRG1 in human trophoblasts and the redistribution of NDRG1 into the nucleus and cytoplasmic membranes associated with the endoplasmic reticulum (ER) and microtubules. Mutation of the phosphopantetheine attachment site (PPAS) within NDRG1 abrogated this pattern of redistribution. Our results shed new light on the impact of cell injury on NDRG1 expression patterns, and suggest that the PPAS domain plays a key role in NDRG1's subcellular distribution. © 2013 Shi et al

Lipid phosphate phosphatase 3 participates in transport carrier formation and protein trafficking in the early secretory pathway

The inhibition of phosphatidic acid phosphatase (PAP) activity by propanolol indicates that diacylglycerol (DAG) is required for the formation of transport carriers at the Golgi and for retrograde trafficking to the ER. Here we report that the PAP2 family member lipid phosphate phosphatase 3 (LPP3, also known as PAP2b) localizes in compartments of the secretory pathway from ER export sites to the Golgi complex. The depletion of human LPP3: (i) reduces the number of tubules generated from the ER-Golgi intermediate compartment and the Golgi, with those formed from the Golgi being longer in LPP3-silenced cells than in control cells; (ii) impairs the Rab6-dependent retrograde transport of Shiga toxin subunit B from the Golgi to the ER, but not the anterograde transport of VSV-G or ssDsRed; and (iii) induces a high accumulation of Golgi-associated membrane buds. LPP3 depletion also reduces levels of de novo synthesized DAG and the Golgi-associated DAG contents. Remarkably, overexpression of a catalytically inactive form of LPP3 mimics the effects of LPP3 knockdown on Rab6-dependent retrograde transport. We conclude that LPP3 participates in the formation of retrograde transport carriers at the ER-Golgi interface, where it transitorily cycles, and during its route to the plasma membrane

Nicolet (Nellie). Der Dialekt des Antronatales. Lautlehre, Formenlehre, Texte, Glossar

Ulrix Eugène. Nicolet (Nellie). Der Dialekt des Antronatales. Lautlehre, Formenlehre, Texte, Glossar. In: Revue belge de philologie et d'histoire, tome 11, fasc. 3-4, 1932. pp. 732-733

Nicolet (Nellie). Der Dialekt des Antronatales. Lautlehre, Formenlehre, Texte, Glossar

Ulrix Eugène. Nicolet (Nellie). Der Dialekt des Antronatales. Lautlehre, Formenlehre, Texte, Glossar. In: Revue belge de philologie et d'histoire, tome 11, fasc. 3-4, 1932. pp. 732-733

Jeanne Vielliard, Le latin des diplômes royaux et chartes privées de l'époque mérovingienne

Ulrix Eugène. Jeanne Vielliard, Le latin des diplômes royaux et chartes privées de l'époque mérovingienne. In: Revue belge de philologie et d'histoire, tome 8, fasc. 1, 1929. pp. 164-165