Structural development of silicated films self-assembled at the air-water interface

The development of structure perpendicular to and in the plane of the interface has been studied for mesoporous silicate films self-assembled at the air/water interface. The use of constrained X-ray and neutron specular reflectometry has enabled a detailed study of the structural development perpendicular to the interface during the pre-growth phase. Off-specular neutron reflectometry and grazing incidence X-ray diffraction has enabled the in-plane structure to be probed with excellent time resolution. The growth mechanism under the surfactant to silicate source ratios used in this work is clearly due to the self-assembly of micellar and molecular species at the air/liquid interface, resulting in the formation of a planar mesoporous film that is tens of microns thick. (C) 2003 Elsevier Science B.V. All rights reserved.

Flotillin-1-enriched lipid raft domains accumulate on maturing phagosomes

Flotillin-1 was recently shown to be enriched on detergent-resistant domains of the plasma membrane called lipid rafts. These rafts, enriched in sphingolipids and cholesterol, sequester certain proteins while excluding others. Lipid rafts have been implicated in numerous cellular processes including signal transduction, membrane trafficking and molecular sorting. In this study, we demonstrate both morphologically and biochemically that lipid rafts are present on phagosomes, These structures are enriched in flotillin-1 and devoid of the main phagosomes membrane protein lysosomal-associated membrane protein (LAMP1), The flotillin-1 present on phagosomes does not originate from the plasma membrane during phagocytosis but accumulates gradually on maturing phagosomes, Treatment with bafilomycin A1, a compound that inhibits the proton pump ATPase and prevents the fusion of phagosomes with late endocytic organelles, prevents the acquisition of flotillin-1 by phagosomes, indicating that this protein might be recruited on phagosomes from endosomal organelles. A proteomic characterization of the lipid rafts of phagosomes indicates that actin, the alpha- and beta -subunits of heterotrimeric G proteins, as well as subunits of the proton pump V-ATPase are among the constituents of these domains. Remarkably, the intracellular parasite Leishmania donovani can actively inhibit the acquisition of flotillin-1-enriched lipid rafts by phagosomes and the maturation of these organelles. These results indicate that specialized functions required for phagolysosome biogenesis may occur at focal points on the phagosome membrane, and therefore represent a potential target of intracellular pathogens.

Biomolecular engineering at interfaces

A broad review of technologically focused work concerning biomolecules at interfaces is presented. The emphasis is on developments in interfacial biomolecular engineering that may have a practical impact in bioanalysis, tissue engineering, emulsion processing or bioseparations. We also review methods for fabrication in an attempt to draw out those approaches that may be useful for product manufacture, and briefly review methods for analysing the resulting interfacial nanostructures. From this review we conclude that the generation of knowledge and-innovation at the nanoscale far exceeds our ability to translate this innovation into practical outcomes addressing a market need, and that significant technological challenges exist. A particular challenge in this translation is to understand how the structural properties of biomolecules control the assembled architecture, which in turn defines product performance, and how this relationship is affected by the chosen manufacturing route. This structure-architecture-process-performance (SAPP) interaction problem is the familiar laboratory scale-up challenge in disguise. A further challenge will be to interpret biomolecular self- and directed-assembly reactions using tools of chemical reaction engineering, enabling rigorous manufacturing optimization of self-assembly laboratory techniques. We conclude that many of the technological problems facing this field are addressable using tools of modem chemical and biomolecular engineering, in conjunction with knowledge and skills from the underpinning sciences. (c) 2005 Elsevier Ltd. All rights reserved.

Heritabilities of Apolipoprotein and Lipid Levels in Three Countries

This study investigated the influence of genes and environment on the variation of apolipoprotein and lipid levels, which are important intermediate phenotypes in the pathways toward cardiovascular disease. Heritability estimates are presented, including those for apolipoprotein E and All levels which have rarely been reported before. We studied twin samples from the Netherlands (two cohorts; n = 160 pairs, aged 13-22 and n = 204 pairs, aged 34-62), Australia (n = 1362 pairs, aged 28-92) and Sweden (n = 302 pairs, aged 42-88). The variation of apolipoprotein and lipid levels depended largely on the influences of additive genetic factors in each twin sample. There was no significant evidence for the influence of common environment. No sex differences in heritability estimates for any phenotype in any of the samples were observed. Heritabilities ranged from 0.48-0.87, with most heritabilities exceeding 0.60. The heritability estimates in the Dutch samples were significantly higher than in the Australian sample. The heritabilities for the Swedish were intermediate to the Dutch and the Australian samples and not significantly different from the heritabilities in these other two samples. Although sample specific effects are present, we have shown that genes play a major role in determining the variance of apolipoprotein and lipid levels in four independent twin samples from three different countries.

Stress associated with the transition from high school to university: The effect of social support and self-efficacy

The present study aimed to evaluate the role of social support and self-efficacy on the level of stress associated with the transition from high school to university. One hundred and eight-five university students who had completed high school in the previous year completed a three-part questionnaire designed to gather information on their levels of self-efficacy, social support, and stress associated with their transition. The results showed that self-efficacy was a significant predictor of stress associated with the transition to university in that higher levels of self-efficacy were associated with lower levels of stress while social support was a non-significant predictor of stress. [Author abstract]

Loyalty without Conformity: Tailoring Self-perception as a Means of Balancing Belonging and Differentiation

We argue that members of individualist cultures balance their desire to belong with their desire to be different by maintaining a self-image as being loyal but relatively immune to group influence. Consistent with this, in Study 1 there was a strong tendency for people to rate themselves as being more independent (i.e., less conformist) than other people in their college. College students also rated themselves as being highly loyal to the group, however no self - other discrepancies were found on this dimension. This is despite the fact that traits of loyalty were rated more positively than were traits of independence. Study 2 provided evidence that culture influences the pattern of self - other discrepancies. Whereas people from individualist countries self-enhance on independence dimensions, people from collectivist countries self-enhance on loyalty dimensions. Again, these effects could not be explained as being a function of how positive these traits were seen to be, suggesting a cultural explanation rather than a straight forward superiority bias explanation for the observed discrepancies in self - other ratings. Results are discussed in relation to the SCENT model.

Enhanced energy status of corals on coastal, high-turbidity reefs

Sedimentation and high turbidity have long been considered a major threat to corals, causing world-wide concern for the health of coral reefs in coastal environments. While studies have demonstrated that sediment conditions characteristic of inshore reefs cause stress in corals, the consequences of such conditions for the physiological status of corals require testing in field situations. Here, I compare the size of energy stores (as lipid content), a proxy for physiological condition, of 2 coral species (Turbinaria mesenterina and Acropora valida) between coastal and offshore environments. Corals on coastal reefs contained 4-fold (T mesenterina) and 2-fold (A. valida) more lipid than conspecifics offshore, despite 1 order of magnitude higher turbidity levels inshore. Results were consistent across 4 sites in each environment. Reproductive investment in A. valida (a seasonal mass spawner) did not vary between environments, suggesting that the larger lipid stores in corals on coastal reefs are mainly somatic energy reserves. These results demonstrate that the environmental conditions on inshore, high-turbidity reefs do not always impact negatively on the physiology of corals. The contrasting lipid levels of T. mesenterina between environments may explain its greater success on coastal reefs.

Reversible active switching of the mechanical properties of a peptide film at a fluid-fluid interface

Designer peptides have recently been developed as building blocks for novel self-assembled materials with stimuli-responsive properties. To date, such materials have been based on self-assembly in bulk aqueous solution or at solid-fluid interfaces. We have designed a 21-residue peptide, AM1, as a stimuli-responsive surfactant that switches molecular architectures at a fluid-fluid interface in response to changes in bulk aqueous solution composition. In the presence of divalent zinc at neutral pH, the peptide forms a mechanically strong 'film state'. In the absence of metal ions or at acid pH, the peptide adsorbs to form a mobile 'detergent state'. The two interfacial states can be actively and reversibly switched. Switching between the two states by a change in pH or the addition of a chelating agent leads to rapid emulsion coalescence or foam collapse. This work introduces a new class of surfactants that offer an environmentally friendly approach to control the stability of interfaces in foams, emulsions and fluid-fluid interfaces more generally.

Perspectives on quality of life by people with aphasia and their family: Suggestions for successful living

Understanding the client's perspective is essential for good practitioner care in rehabilitation after stroke, and nothing is more relevant than enquiring directly about our clients' quality of life to inform our management. Relatively little is known about how older people with aphasia consider the quality of their current lives, and this article seeks to explore this issue. Four women's accounts of their life quality are presented, as well as their husbands' or daughter's accounts of their lives. Their stories share some common elements. Who you love or share your life with; where you live; feeling independent and/or in control; and engaging in satisfying activities mattered to these women's life quality. The impact of aphasia varies across the cases, and the need to accept change for successful living is illustrated in all accounts.

Self-efficacy and task performance: An investigation from two levels of analysis and specificity

This research adopts a resource allocation theoretical framework to generate predictions regarding the relationship between self-efficacy and task performance from two levels of analysis and specificity. Participants were given multiple trials of practice on an air traffic control task. Measures of task-specific self-efficacy and performance were taken at repeated intervals. The authors used multilevel analysis to demonstrate dynamic main effects, dynamic mediation and dynamic moderation. As predicted, the positive effects of overall task specific self-efficacy and general self-efficacy on task performance strengthened throughout practice. In line with these dynamic main effects, the effect of general self-efficacy was mediated by overall task specific self-efficacy; however this pattern emerged over time. Finally, changes in task specific self-efficacy were negatively associated with changes in performance at the within-person level; however this effect only emerged towards the end of practice for individuals with high levels of overall task specific self-efficacy. These novel findings emphasise the importance of conceptualising self-efficacy within a multi-level and multi-specificity framework and make a significant contribution to understanding the way this construct relates to task performance.

A safety catch linker for Fmoc-based assembly of constrained cyclic peptides

A new safety-catch linker for Fmoc solid-phase peptide synthesis of cyclic peptides is reported. The linear precursors were assembled on a tert-butyl protected catechol derivative using optimized conditions for Fmoc-removal. After activation of the linker using TFA, neutralization of the N-terminal amine induced cyclization with concomitant cleavage from the resin yielding the cyclic peptides in DMF solution. Several constrained cyclic peptides were synthesized in excellent yields and purities. Copyright (c) 2005 European Peptide Society and John Wiley & Sons, Ltd.

Psychosocial and non-psychosocial risk factors for the new diagnosis of diabetes in elderly women

Objectives: Determine psychosocial variables associated with the new diagnosis of diabetes in elderly women. Examine whether variables remained significant predictors after controlling for non-psychosocial risk factors and the frequency of doctor visits. Research design and methods: A longitudinal cohort study was conducted using data from 10 300 women who completed a survey in 1996 and 1999. The women were aged between 70 and 74 years of age in 1996. The were asked to provide self-reports on a number of psychosocial and non-psychosocial variables in 1996 and on whether they had been diagnosed for the first time with diabetes in the 3-year period. The relationships between the potential risk factors and new diagnosis of diabetes were examined using binary logistic regression analysis. Results: Univariate results showed that not having a current partner, having low social support and having a mental health index score in the clinical range were all associated with higher risks of being diagnosed with diabetes for the first time. However the multivariate results showed that only a mental health index score in the clinical range and not having a current partner provided unique prediction of being newly diagnosed with diabetes. Of the non-psychosocial variables measured, only having a high BMI and hypertension were associated with increased risks of new diagnosis, while there was also evidence of a U shaped relationship between alcohol consumption and new diagnosis. Even after adjusting for frequency of doctor visits and non-psychosocial risk factors, a mental health index in the clinical range proved to still be a significant risk factor. Conclusions: A score on the mental health index that is within the clinical range is an independent risk factor for the new diagnosis of diabetes in elderly women. (c) 2006 Elsevier Ireland Ltd. All rights reserved.

Molecular dynamics simulations of the hydrophobin SC3 at a hydrophobic/hydrophilic interface

Hydrophobins are small (similar to 100 aa) proteins that have an important role in the growth and development of mycelial fungi. They are surface active and, after secretion by the fungi, self-assemble into amphipathic membranes at hydrophobic/hydrophilic interfaces, reversing the hydrophobicity of the surface. In this study, molecular dynamics simulation techniques have been used to model the process by which a specific class I hydrophobin, SC3, binds to a range of hydrophobic/ hydrophilic interfaces. The structure of SC3 used in this investigation was modeled based on the crystal structure of the class II hydrophobin HFBII using the assumption that the disulfide pairings of the eight conserved cysteine residues are maintained. The proposed model for SC3 in aqueous solution is compact and globular containing primarily P-strand and coil structures. The behavior of this model of SC3 was investigated at an air/water, an oil/water, and a hydrophobic solid/water interface. It was found that SC3 preferentially binds to the interfaces via the loop region between the third and fourth cysteine residues and that binding is associated with an increase in a-helix formation in qualitative agreement with experiment. Based on a combination of the available experiment data and the current simulation studies, we propose a possible model for SC3 self-assembly on a hydrophobic solid/water interface.