Effects of process on microstructure and properties of translucent Dy-alpha-SiAlON sintered at lower temperatures

Hot pressing (HP) at higher sintering temperature has been a traditional and prevalent technique for the fabrication of alpha-SiAlON. In order to prepare translucent SiAlON more easily, LiF was used as a non-oxide sintering additive to lower the sintering temperature to <= 1650 degrees C. As a result, all of the samples possessed a good hardness and fracture toughness. At the same time, the lower temperature sintered samples showed a higher optical transmittance in the range of 2.5-5.5 mu m wavelength (0.5 mm in thickness). The maximum infrared transmission reached 68% at a wavelength of 3.3 mu m. The present work shows that the sintering process has a strong effect on microstructure and property of alpha-SiAlON. To be exact, a lower sintering temperature and longer holding time can produce some fully-developed microstrcture, which is beneficial for the optical transmittance. (C) 2008 The Ceramic Society of Japan. All rights reserved.

Influence of Extracellular Matrix Components on the Expression of Integrins and Regeneration of Adult Retinal Ganglion Cells

Purpose Retinal ganglion cells (RGCs) are exposed to injury in a variety of optic nerve diseases including glaucoma. However, not all cells respond in the same way to damage and the capacity of individual RGCs to survive or regenerate is variable. In order to elucidate factors that may be important for RGC survival and regeneration we have focussed on the extracellular matrix (ECM) and RGC integrin expression. Our specific questions were: (1) Do adult RGCs express particular sets of integrins in vitro and in vivo? (2) Can the nature of the ECM influence the expression of different integrins? (3) Can the nature of the ECM affect the survival of the cells and the length or branching complexity of their neurites? Methods Primary RGC cultures from adult rat retina were placed on glass coverslips treated with different substrates: Poly-L-Lysine (PL), or PL plus laminin (L), collagen I (CI), collagen IV (CIV) or fibronectin (F). After 10 days in culture, we performed double immunostaining with an antibody against beta III-Tubulin to identify the RGCs, and antibodies against the integrin subunits: alpha V, alpha 1, alpha 3, alpha 5, beta 1 or beta 3. The number of adhering and surviving cells, the number and length of the neurites and the expression of the integrin subunits on the different substrates were analysed. Results PL and L were associated with the greatest survival of RGCs while CI provided the least favourable conditions. The type of substrate affected the number and length of neurites. L stimulated the longest growth. We found at least three different types of RGCs in terms of their capacity to regenerate and extend neurites. The different combinations of integrins expressed by the cells growing on different substrata suggest that RGCs expressed predominantly alpha 1 beta 1 or alpha 3 beta 1 on L, alpha 1 beta 1 on CI and CIV, and alpha 5 beta 3 on F. The activity of the integrins was demonstrated by the phosphorylation of focal adhesion kinase (FAK). Conclusions Adult rat RGCs can survive and grow in the presence of different ECM tested. Further studies should be done to elucidate the different molecular characteristics of the RGCs subtypes in order to understand the possible different sensitivity of different RGCs to damage in diseases like glaucoma in which not all RGCs die at the same time.

Natural Variation In Recovery From A Short Period Of Anoxia Due To A cGMP-Dependent Protein Kinase in Drosophila melanogaster

[EN] Protein Kinase G (PKG) or cGMP-dependent protein kinases (PKG) have been shown to play an important role in resistance to abiotic stressors such as high temperatures or oxygen deprivation in Drosophila melanogaster. In Drosophila, the foraging gene encodes a PKG; natural variants for this gene exist, which differ in the level of expression of PKG: rovers (forR allele) which express high PKG levels, and sitters (forS allele) which express lower PKG levels. This project explores the differences in recovery from short periods of anoxia between natural variants (focusing on forS2, flies with a sitter gene in a rover background), as well as mutants with insertions in the foraging gene and RNAi recombinants that show a reduced PKG expression. The parameters measured were time to recovery and level of activity after anoxia. The results showed lower activity after anoxia in sitters than in rovers, reflecting a worse recovery from the anoxic coma in flies with lower PKG levels.

Energetics and Structural Characterization of the large-scale Functional Motion of Adenylate Kinase

Adenylate Kinase (AK) is a signal transducing protein that regulates cellular energy homeostasis balancing between different conformations. An alteration of its activity can lead to severe pathologies such as heart failure, cancer and neurodegenerative diseases. A comprehensive elucidation of the large-scale conformational motions that rule the functional mechanism of this enzyme is of great value to guide rationally the development of new medications. Here using a metadynamics-based computational protocol we elucidate the thermodynamics and structural properties underlying the AK functional transitions. The free energy estimation of the conformational motions of the enzyme allows characterizing the sequence of events that regulate its action. We reveal the atomistic details of the most relevant enzyme states, identifying residues such as Arg119 and Lys13, which play a key role during the conformational transitions and represent druggable spots to design enzyme inhibitors. Our study offers tools that open new areas of investigation on large-scale motion in proteins.

Dieta hiperlipídica e/ou rica em sacarose em camundongos suíços: metabolismo de carboidratos, fígado e tecido adiposo

A doença hepática gordurosa não alcoólica é uma desordem multifatorial causada principalmente por excesso nutricional e resistência à insulina, com prevalência estimada de 20-40% nos países ocidentais. A dieta hiperlipídica e/ou rica em sacarose pode influenciar no desenvolvimento da esteatose hepática associada à obesidade e a resistência à insulina. O fígado, por assumir papel central no controle metabólico, é um órgão alvo nos casos de excesso alimentar, ocasionando, principalmente, acúmulo de gotículas de gordura nos hepatócitos. Este trabalho teve como objetivo avaliar o início das alterações morfológicas e metabólicas no fígado e no tecido adiposo de camundongos suíços machos alimentados com dieta hiperlipídica e/ou rica em sacarose. Camundongos suíços machos aos três meses de idade foram divididos em quatro grupos nutricionais: dieta padrão (SC), dieta hiperlipídica (HF), dieta rica em sacarose (HSu) e dieta hiperlipídica rica em sacarose (HFHSu). Os animais receberam as respectivas dietas durante quatro semanas. A massa corporal, a ingestão alimentar e a tolerância oral à glicose foram avaliados. Ao sacrifício, o fígado e os depósitos de gordura corporal foram removidos e processados para análises histomorfométricas e moleculares. As amostras de sangue foram obtidas para análises bioquímicas plasmáticas. Os dados foram expressos como média e erro padrão da média e as diferenças foram testadas por one-way ANOVA com pós-teste de Holm-Sidak, e foi considerado o nível de significância de p<0,05. Os grupos HF e HFHSu apresentaram-se mais pesados quando comparados aos grupos SC e HSu. Os animais dos grupos HF, HSu e HFHSu apresentaram intolerância à glicose, esteatose hepática e aumento de triglicerídeos hepáticos quando comparados ao grupo SC (p<0,0005). Adicionalmente, houve elevação na expressão hepática das proteínas transportador de glicose 2 (GLUT-2), proteína de ligação ao elemento regulador do esterol 1-c (SREBP1-c), fosfoenolpiruvato carboxiquinase (PEPCK), glicose -6- fosfatase (G6PASE), substrato do receptor da insulinaI-1 (IRS-1) e proteína quinase B (AKt/ou PKB) e redução da expressão no fígado do receptor ativador de proliferação peroxissomal (PPAR-α) nos grupos experimentais em comparação com o grupo SC (p<0,0005). A administração de dieta hiperlipídica e/ou rica em sacarose promoveu intolerância à glicose e danos hepáticos (hepatomegalia, esteatose, redução da beta-oxidação, aumento na lipogênese e na produção de glicose) em camundongos machos adultos.

Adaptive evolution of primate TRIM5 alpha, a gene restricting HIV-1 infection

Recent studies showed that nonhuman primate TRIM5 alpha can efficiently block HIV-1 infection in human cell lines. It can also restrict other retroviruses, therefore, suggested as a general defender against retrovirus infection. Here, we present an evolutionary analysis of TRIM5 alpha in primates. Our results demonstrated that TRIM5a has been evolving rapidly in primates, which is likely caused by Darwinian positive selection. The SPRY domain of TRM5 alpha, which may be responsible for recognition of incoming viral capsids showed higher nonsynonymous/synonymous substitution ratios than the non-SPRY domain, indicating that the adaptive evolution of TRIM5a ill primates might be an innate strategy developed in defending retrovirus infection during primate evolution. In addition, the comparative protein sequence analysis suggested that the amino acid substitution pattern at a single site (344R/Q/P) located in the SPRY domain may explain the differences in Susceptibilities of HIV-1 infection in diverse primate species. (c) 2005 Elsevier B.V. All rights reserved.

Cloning and purification of alpha-neurotoxins from king cobra (Ophiophagus hannah)

Thirteen complete and three partial cDNA sequences were cloned from the constructed king cobra (Ophiophagus hannah) venom gland cDNA library. Phylogenetic analysis of nucleotide sequences of king cobra with those from other snake venoms revealed that obta

Enhanced poisson sum representation for alpha-stable processes

In this paper we present Poisson sum series representations for α-stable (αS) random variables and a-stable processes, in particular concentrating on continuous-time autoregressive (CAR) models driven by α-stable Lévy processes. Our representations aim to provide a conditionally Gaussian framework, which will allow parameter estimation using Rao-Blackwellised versions of state of the art Bayesian computational methods such as particle filters and Markov chain Monte Carlo (MCMC). To overcome the issues due to truncation of the series, novel residual approximations are developed. Simulations demonstrate the potential of these Poisson sum representations for inference in otherwise intractable α-stable models. © 2011 IEEE.

The free alpha amino acid nitrogen contents of some common food fishes of Kakinada region, Andhra Pradesh

The moisture and free alpha amino nitrogen contents of some important food fishes and shell fishes of Kakinada region have been studied. Crustaceans and molluscs contain free alpha amino acids in quantities several times higher than all other aquatic animals examined in this study. Their probable role in the physiological activities of these animals has been discussed.

Polymorphisms of the estrogen receptor alpha (ESR1) gene and the risk of Alzheimer's disease in a southern Chinese community

Background: Alzheimer's disease (AD) is a neurodegenerative disease with a higher prevalence in women. Expression of estrogen receptor 1 (ESR1) gene has been identified throughout the brain. Owing to the putative neuroprotective effects of estrogen, estro