Two-dimensional liquid crystal laser array

A two-dimensional liquid crystal (LC) laser array has been demonstrated by photopumping a single LC sample using a lenslet array consisting of plano-convex microlenses. A 5 × 5 array of LC lasers (displaying evidence of mutual coherence) spaced by 1 mm inactive regions has been generated, which could be combined to yield a single monomode output and allows an almost 50-fold increase in energy density in comparison to a single-focus LC cavity. Furthermore, we have demonstrated how the individual and recombined emission spectra vary with different sample topologies and how polydomain samples can be used to generate a multiwavelength laser emission. © 2008 Optical Society of America.

Differential activity of GSK-3 isoforms regulates NF-kappa B and TRAIL- or TNF alpha induced apoptosis in pancreatic cancer cells

While TRAIL is a promising anticancer agent due to its ability to selectively induce apoptosis in neoplastic cells, many tumors, including pancreatic ductal adenocarcinoma (PDA), display intrinsic resistance, highlighting the need for TRAIL-sensitizing agents. Here we report that TRAIL-induced apoptosis in PDA cell lines is enhanced by pharmacological inhibition of glycogen synthase kinase-3 (GSK-3) or by shRNA-mediated depletion of either GSK-3 alpha or GSK-3 beta. In contrast, depletion of GSK-3 beta, but not GSK-3 alpha, sensitized PDA cell lines to TNF alpha-induced cell death. Further experiments demonstrated that TNF alpha-stimulated I kappa B alpha phosphorylation and degradation as well as p65 nuclear translocation were normal in GSK-3 beta-deficient MEFs. Nonetheless, inhibition of GSK-3 beta function in MEFs or PDA cell lines impaired the expression of the NF-kappa B target genes Bcl-xL and cIAP2, but not I kappa B alpha. Significantly, the expression of Bcl-xL and cIAP2 could be reestablished by expression of GSK-3 beta targeted to the nucleus but not GSK-3 beta targeted to the cytoplasm, suggesting that GSK-3 beta regulates NF-kappa B function within the nucleus. Consistent with this notion, chromatin immunoprecipitation demonstrated that GSK-3 inhibition resulted in either decreased p65 binding to the promoter of BIR3, which encodes cIAP2, or increased p50 binding as well as recruitment of SIRT1 and HDAC3 to the promoter of BCL2L1, which encodes Bcl-xL. Importantly, depletion of Bcl-xL but not cIAP2, mimicked the sensitizing effect of GSK-3 inhibition on TRAIL-induced apoptosis, whereas Bcl-xL overexpression ameliorated the sensitization by GSK-3 inhibition. These results not only suggest that GSK-3 beta overexpression and nuclear localization contribute to TNF alpha and TRAIL resistance via anti-apoptotic NF-kappa B genes such as Bcl-xL, but also provide a rationale for further exploration of GSK-3 inhibitors combined with TRAIL for the treatment of PDA.

Two Glass Transitions Associated to Different Dynamic Disorders in the Nematic Glassy State of a Non-Symmetric Liquid Crystal Dimer Dopped with gamma-Alumina Nanoparticles

In the present work, the nematic glassy state of the non-symmetric LC dimer -(4-cyanobiphenyl-4-yloxy)--(1-pyrenimine-benzylidene-4-oxy) undecane is studied by means of calorimetric and dielectric measurements. The most striking result of the work is the presence of two different glass transition temperatures: one due to the freezing of the flip-flop motions of the bulkier unit of the dimer and the other, at a lower temperature, related to the freezing of the flip-flop and precessional motions of the cyanobiphenyl unit. This result shows the fact that glass transition is the consequence of the freezing of one or more coupled dynamic disorders and not of the disordered phase itself. In order to avoid crystallization when the bulk sample is cooled down, the LC dimer has been confined via the dispersion of -alumina nanoparticles, in several concentrations.

Pharmacological Blockade of Cannabinoid CB1 Receptors in Diet-Induced Obesity Regulates Mitochondrial Dihydrolipoamide Dehydrogenase in Muscle

Cannabinoid CB1 receptors peripherally modulate energy metabolism. Here, we investigated the role of CB1 receptors in the expression of glucose/pyruvate/tricarboxylic acid (TCA) metabolism in rat abdominal muscle. Dihydrolipoamide dehydrogenase (DLD), a flavoprotein component (E3) of alpha-ketoacid dehydrogenase complexes with diaphorase activity in mitochondria, was specifically analyzed. After assessing the effectiveness of the CB1 receptor antagonist AM251 (3 mg kg(-1), 14 days) on food intake and body weight, we could identified seven key enzymes from either glycolytic pathway or TCA cycle-regulated by both diet and CB1 receptor activity-through comprehensive proteomic approaches involving two-dimensional electrophoresis and MALDI-TOF/LC-ESI trap mass spectrometry. These enzymes were glucose 6-phosphate isomerase (GPI), triosephosphate isomerase (TPI), enolase (Eno3), lactate dehydrogenase (LDHa), glyoxalase-1 (Glo1) and the mitochondrial DLD, whose expressions were modified by AM251 in hypercaloric diet-induced obesity. Specifically, AM251 blocked high-carbohydrate diet (HCD)-induced expression of GPI, TPI, Eno3 and LDHa, suggesting a down-regulation of glucose/pyruvate/lactate pathways under glucose availability. AM251 reversed the HCD-inhibited expression of Glo1 and DLD in the muscle, and the DLD and CB1 receptor expression in the mitochondrial fraction. Interestingly, we identified the presence of CB1 receptors at the membrane of striate muscle mitochondria. DLD over-expression was confirmed in muscle of CB1-/- mice. AM251 increased the pyruvate dehydrogenase and glutathione reductase activity in C2C12 myotubes, and the diaphorase/oxidative activity in the mitochondria fraction. These results indicated an up-regulation of methylglyoxal and TCA cycle activity. Findings suggest that CB1 receptors in muscle modulate glucose/pyruvate/lactate pathways and mitochondrial oxidative activity by targeting DLD.

Estudo comparativo do teor de (15E)-licopeno por CLAE-DAD entre lavouras de tomate submetidas aos manejos TOMATEC e tradicional

O tomate (Solanum lycopersicum L.) é considerado um alimento funcional por sua propriedade antioxidante. O fruto contém dos carotenoides, ácido L-ascórbico, vitamina E e substâncias fenólicas. Estudos indicam que o consumo do tomate pode retardar o envelhecimento e favorecer o funcionamento do sistema imunológico em humanos, embora não seja possível afirmar uma relação direta entre a prevenção ou cura de qualquer carcinoma com o consumo de produtos à base licopeno. Na década de 1990, a Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) criou o projeto TOMATEC, o tomate ecologicamente cultivado. A produção é baseada em um manejo diferenciado, que objetiva a otimização do uso do solo, menor consumo de pesticidas, herbicidas e incentivo à produção familiar dos agricultores. O estudo objetiva observar a influencia dos diferentes manejos: tradicional e TOMATEC na produção de (15E)-licopeno nos frutos do tomate, em diferentes cultivares do Brasil. Assim, foi utilizada a técnica de cromatografia líquida de alta eficiência acoplada a detector por arranjo de diodos (CLAE-DAD), em fase estacionária polimérica composta de 30 carbonos (C30). Esta fase estacionária é capaz de separar carotenoides, incluvise, isômeros geométricos do licopeno. As amostras foram coletadas, tratadas, extraídas e analisadas sob as mesmas condições para avaliação das concentrações de (15E)-licopeno nos frutos. Ensaios realizados foram capazes de demonstrar, de maneira objetiva, que a metodologia proposta conduziu a resultados confiáveis à qualidade desejada, de acordo com o guia de validação proposto pelo Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO). Foram utilizadas ferramentas estatísticas para comparar os teores de (15E)-licopeno, em diferentes Estados do Brasil, sob diferentes manejos. Os resultados indicam os maiores teores da substância em cultivares convencionais e mostram que o ensacamento do fruto é um fator decisivo para a biossíntese do (15E)-licopeno

A global experiment on tilapia aquaculture: impacts of the Pond Dynamics/Aquaculture CRSP in Rwanda, Honduras, Philippines and Thailand

The Pond Dynamics/Aquaculture Collaborative Research Support Program (PDA/CRSP) is a global research network to generate basic science that may be used to advance aquaculture development. One of a family of research programs funded by the United States Agency for International Development (USAID), the CRSP focuses on improving the efficiency of aquaculture systems. The PDA/CRSP began work in 1982 in Thailand, and subsequently in the Philippines, Honduras, the US and, until recently, Rwanda. At all the sites, the goal is the same: to identify constraints to aquaculture production, and to design responses that are environmentally and culturally appropriate. The research network's global experiment has focused on tilapia (Oreochromis niloticus), although some sites have devoted attention to marine shrimp and other locally significant species. Impact of the network's investigations with tilapia is examined in this article.

Estudo dos modos de Plasmon em Fibras fracamente guiadas com camadas dielétricas sobre Filme Metálico.

Neste trabalho são analisados os quatro modos de plasmon, ligados simétrico (Sb) e assimétrico (ab), fuga pelo núcleo (ln) e fuga pela cobertura (lc), que se propagam em uma fibra óptica fracamente guiada envolta por um filme metálico. No filme metálico é depositada uma camada dielétrica extra e acima desta, uma outra denominada cobertura. A análise será desenvolvida para filmes metálicos de prata, paládio e ouro. Esta estrutura é muito útil na confecção de sensores ópticos.