Fases de membranas fluidas -L3 a partir de lipídio sintético e pentanol na região diluída - e o respectivo dialisado

Abstract: The amphiphilic L3 (sponge) phase was observed in the late 80's and represents a new class of self-assembly for surfactant-water systems. This work describes the discovery and subsequent characterization of a ternary phase composed of synthetic cationic lipid dioctadecildimetil ammonium bromide (DODAB), pentanol and water in a diluted region. This is the first description of a L3 phase prepared from a lipid with a relatively small polar head and two hydrocarbon chains with 18 carbons each one. The region of the triangle diagram in which there is L3 phase was characterized using optical isotropy and anisotropy to a probe with electron paramagnetic resonance spectroscopy technique. The proposal of an L3 phase was made by comparison with a similar system reported by the group of Montpellier. The description accepted is that in a narrow close ratio of surfactant/cosolvent concentrations, membrane fusion occurs with the formation of a highly interconnected and randomly distributed network of bilayers in space. The assumption of formation of the L3 phase is that the hydroxyl group of pentanol pairs with the lipid heads and this fact is able to change the bilayer curvature. The various DODAB/pentanol preparations remained unchanged and stable for five years only up to the concentration of 3 mM of lipid, the maximum concentration that can be called L3 phase, which is thermodynamically stable. To make the system more attractive for many potential uses it was necessary to increase the weight of the lipid. Concentrations up to 10 millimolar, after a few hours, break down into tiny droplets and small crystals, so-called multiphase. The next step was to completely remove the alcohol by continuous dialysis. The result was the appearance of a phase similar to water, which cannot be obtained otherwise. A sequence of spectroscopic and chromatography measurements showed that the alcohol was entirely eliminated by dialysis as the lipid was retained. There is a notable change when compared with other DODAB/water binary preparations. In the same concentration, all of them have pronounced turbidity. The hypothesis is that the presence of alcohol in the bilayer promotes reorganization, transforming a particulate into a bicontinuum system. Efforts to characterize these systems are justified because they are easy to prepare and have potential uses in the synthesis of inorganic solid new materials with nanostructured pores, and as drug carriers and vehicles for the crystallization of proteins.Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química

Floating formulation for Bacillus thuringiensis var. israelensis obtained from semi-solid rice medium.

A loopful of Bti mantained on Luria-Bertani agar medium was transferred to Bacto-Peptona agar medium. After 3 days at 30oC, the petri-disheswere washed with sterilized water (100ml/petri-dish). The suspension obtained represented the inoculum for the semi-solid rice-based fermentation medium. The growth units were incubated until complete sporulation of Bti. The resulting biomass was dried at 60oC in an oven for 24h, sieved through 60 tyler. The retained powder did not show any larvicidal activity. In parallel, colloidal bentonite was treated with organic macromolecules dissolved in toluene, after sedimentation, the botton phase was dried at 120oC for 4h. This treatment led to a spreading and floating clay which resulted in a good carrier for Bti. Then, the the two powders were mixed in the proportion of 1(Bti):150(clay). The bioassays were performed under laboratory conditions utilizing 2nd instar Culex sp. larvae, with 3 repetitions (20 larvae each) being observed during 96 hours. The data were treated with Abbott method. A complete methodology was developed to get floating units of Bti with 143 mg/m2 of biological activity

Intermediate Phenotypes Identify Divergent Pathways to Alzheimer's Disease

Background: Recent genetic studies have identified a growing number of loci with suggestive evidence of association with susceptibility to Alzheimer's disease (AD). However, little is known of the role of these candidate genes in influencing intermediate phenotypes associated with a diagnosis of AD, including cognitive decline or AD neuropathologic burden. Methods/Principal Findings: Thirty-two single nucleotide polymorphisms (SNPs) previously implicated in AD susceptibility were genotyped in 414 subjects with both annual clinical evaluation and completed brain autopsies from the Religious Orders Study and the Rush Memory and Aging Project. Regression analyses evaluated the relation of SNP genotypes to continuous measures of AD neuropathology and cognitive function proximate to death. A SNP in the zinc finger protein 224 gene (ZNF224, rs3746319) was associated with both global AD neuropathology (p = 0.009) and global cognition (p = 0.002); whereas, a SNP at the phosphoenolpyruvate carboxykinase locus (PCK1, rs8192708) was selectively associated with global cognition (p = 3.57×10−4). The association of ZNF224 with cognitive impairment was mediated by neurofibrillary tangles, whereas PCK1 largely influenced cognition independent of AD pathology, as well as Lewy bodies and infarcts. Conclusions/Significance: The findings support the association of several loci with AD, and suggest how intermediate phenotypes can enhance analysis of susceptibility loci in this complex genetic disorder

Adaptive Evolution in Zinc Finger Transcription Factors

The majority of human genes are conserved among mammals, but some gene families have undergone extensive expansion in particular lineages. Here, we present an evolutionary analysis of one such gene family, the poly–zinc-finger (poly-ZF) genes. The human genome encodes approximately 700 members of the poly-ZF family of putative transcriptional repressors, many of which have associated KRAB, SCAN, or BTB domains. Analysis of the gene family across the tree of life indicates that the gene family arose from a small ancestral group of eukaryotic zinc-finger transcription factors through many repeated gene duplications accompanied by functional divergence. The ancestral gene family has probably expanded independently in several lineages, including mammals and some fishes. Investigation of adaptive evolution among recent paralogs using dN/dS analysis indicates that a major component of the selective pressure acting on these genes has been positive selection to change their DNA-binding specificity. These results suggest that the poly-ZF genes are a major source of new transcriptional repression activity in humans and other primates

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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