Bilayer Properties of 1,3-Diamidophospholipids

A series of 1,3-diamido phosphocholines was synthesized, and their potential to form stable bilayers was investigated. Large and giant unilamellar vesicles produced from these new lipids form a wide variety of faceted liposomes. Factors such as cooling rates and the careful choice of the liposome preparation method influence the formation of facets. Interdigitation was hypothesized as a main factor for the stabilization of facets and effectively monitored by small-angle X-ray scattering measurements

About some robustness and complexity properties of G-graphs networks

Given a finite group G and a set S ⊂ G, we consider the different cosets of each cyclic group ⟨s⟩ with s ∈ S. Then the G-graph Φ(G, S) associated with G and S can be defined as the intersection graph of all these cosets. These graphs were introduced in Bretto and Faisant (2005) as an alternative to Cayley graphs: they still have strong regular properties but a more flexible structure. We investigate here some of their robustness properties (connectivity and vertex/edge-transitivity) recognized as important issues in the domain of network design. In particular, we exhibit some cases where G-graphs are optimally connected, i.e. their edge and vertex-connectivity are both equal to the minimum degree. Our main result concerns the case of a G-graph associated with an abelian group and its canonical base S, which is shown to be optimally connected. We also provide a combinatorial characterization for this class as clique graphs of Cartesian products of complete graphs and we show that it can be recognized in polynomial time. These results motivate future researches in two main directions: revealing new classes of optimally connected G-graphs and investigating the complexity of their recognitio

Vesicle origami and the influence of cholesterol on lipid packing

The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous curvature. Forced into a vesicular structure, Pad-PC-Pad has faceted geometry, and in its extreme form, tetrahedral vesicles were found as predicted a decade ago. Above the main transition temperature, a noninterdigitated Lα phase with fluid chains has been observed. The addition of cholesterol leads to a slight decrease of the main transition temperature and a gradual decrease in the transition enthalpy until the transition vanishes at 40 mol % cholesterol in the mixture. Additionally, cholesterol pulls the chains apart, and a noninterdigitated gel phase is observed. In monolayers, cholesterol has an ordering effect on liquid-expanded phases and disorders condensed phases. The wavenumbers of the methylene stretching vibration indicate the formation of a liquid- ordered phase in mixtures with 40 mol % cholesterol

Crowdsourcing through cognitive opportunistic networks

Until recently crowdsourcing has been primarily conceived as an online activity to harness resources for problem solving. However the emergence of opportunistic networking (ON) has opened up crowdsourcing to the spatial domain. In this paper we bring the ON model for potential crowdsourcing in the smart city envi- ronment. We introduce cognitive features to the ON that allow users’ mobile devices to become aware of the surrounding physical environment. Specifically, we exploit cognitive psychology studies on dynamic memory structures and cognitive heuristics, i.e. mental models that describe how the human brain handles decision- making amongst complex and real-time stimuli. Combined with ON, these cognitive features allow devices to act as proxies in the cyber-world of their users and exchange knowledge to deliver awareness of places in an urban environment. This is done through tags associated with locations. They represent features that are perceived by humans about a place. We consider the extent to which this knowledge becomes available to participants, using interactions with locations and other nodes. This is assessed taking into account a wide range of cognitive parameters. Outcomes are important because this functionality could support a new type of recommendation system that is independent of the traditional forms of networking

Meta-analysis of the relationship between alcohol consumption and coronary heart disease and mortality in type 2 diabetic patients

Aims/hypothesis: This systematic review examines the relationship between alcohol consumption and long-term complications of type 2 diabetes. Meta-analyses could only be performed for total mortality, mortality from CHD, and CHD incidence, because the availability of articles on other complications was too limited. Materials and methods: A PubMed search through to September 2005 was performed and the reference lists of relevant articles examined. Among the relevant articles there were six cohort studies reporting on the risk of total mortality and/or fatal and/or incident CHD in alcohol non-consumers and in at least two groups of alcohol consumers. Results: Statistical pooling showed lower risks in alcohol consumers than in non-consumers (the reference category). The relative risk (RR) of total mortality was 0.64 (95% CI 0.49-0.82) in the <6 g/day category. In the higher alcohol consumption categories (6 to <18, and ≥18 g/day), the RRs of total mortality were not significant. Risks of fatal and total CHD were significantly lower in all three categories of alcohol consumers (<6, 6 to <18 and ≥18 g/day) than in non-consumers, with RRs ranging from 0.34 to 0.75. Conclusions/interpretation: This meta-analysis shows that, as with findings in the general population, moderate alcohol consumption is associated with a lower risk of mortality and CHD in type 2 diabetic populations. © Springer-Verlag 2006.

Dietary Fat Intake and Cognitive Decline in Women With Type 2 Diabetes

OBJECTIVE: Individuals with type 2 diabetes have high risk of late-life cognitive impairment, yet little is known about strategies to modify risk. Targeting insulin resistance and vascular complications—both associated with cognitive decline—may be a productive approach. We investigated whether dietary fat, which modulates glucose and lipid metabolism, might influence cognitive decline in older adults with diabetes. RESEARCH DESIGN AND METHODS: Beginning in 1995–1999, we evaluated cognitive function in 1,486 Nurses' Health Study participants, aged ≥70 years, with type 2 diabetes; second evaluations were conducted 2 years later. Dietary fat intake was assessed regularly beginning in 1980; we considered average intake from 1980 (at midlife) through initial cognitive interview and also after diabetes diagnosis. We used multivariate-adjusted linear regression models to obtain mean differences in cognitive decline across tertiles of fat intake. RESULTS: Higher intakes of saturated and trans fat since midlife, and lower polyunsaturated to saturated fat ratio, were each highly associated with worse cognitive decline in these women. On a global score averaging all six cognitive tests, mean decline among women in the highest trans fat tertile was 0.15 standard units worse than that among women in the lowest tertile (95% CI −0.24 to −0.06, P = 0.002); this mean difference was comparable with the difference we find in women 7 years apart in age. Results were similar when we analyzed diet after diabetes diagnosis. CONCLUSIONS: These findings suggest that lower intakes of saturated and trans fat and higher intake of polyunsaturated fat relative to saturated fat may reduce cognitive decline in individuals with type 2 diabetes.Statistic

Walking to work in Canada: health benefits, socio-economic characteristics and urban-regional variations

<p>Abstract</p> <p>Background</p> <p>There is mounting concern over increasing rates of physical inactivity and overweight/obesity among children and adult in Canada. There is a clear link between the amount of walking a person does and his or her health. The purpose of this paper is to assess the health factors, socio-economic characteristics and urban-regional variations of walking to work among adults in Canada.</p> <p>Methods</p> <p>Data is drawn from two cycles of the Canadian Community Health Survey: 2001 and 2005. The study population is divided into three groups: non-walkers, lower-duration walkers and high-duration walkers. Logistic regression modeling tests the association between levels of walking and health related outcomes (diabetes, high blood pressure, stress, BMI, physical activity), socio-economic characteristics (sex, age, income, education) and place of residence (selected Census Metropolitan Areas).</p> <p>Results</p> <p>In 2005, the presence of diabetes and high blood pressure was not associated with any form of walking. Adults within the normal weight range were more likely to be high-duration walkers. Females and younger people were more likely to be lower-duration walkers but less likely to be high-duration walkers. There was a strong association between SES (particularly relative disadvantage) and walking to work. In both 2001 and 2005, the conditions influencing walking to work were especially prevalent in Canada's largest city, Toronto, as well as in several small to medium sized urban areas including Halifax, Kingston, Hamilton, Regina, Calgary and Victoria.</p> <p>Conclusion</p> <p>A number of strategies can be followed to increase levels of walking in Canada. It is clear that for many people walking to work is not possible. However, strategies can be developed to encourage adults to incorporate walking into their daily work and commuting routines. These include mass transit walking and workplace walking programs.</p

Obesity and Sugar‐sweetened Beverages in African‐American Preschool Children: A Longitudinal Study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93655/1/oby.2008.656.pd

Genetic polymorphisms of angiotensin-2 type 1 receptor and angiotensinogen and risk of renal dysfunction and coronary heart disease in type 2 diabetes mellitus

<p>Abstract</p> <p>Background</p> <p>Increased activation of the renin-angiotensin system (RAS) may be important in promoting coronary heart disease (CHD) and renal dysfunction, but limited data are available on associations between angiotensin type 1 receptor (<it>AGT1R</it>) and angiotensinogen (<it>AGT</it>) genotypes in type 2 diabetes.</p> <p>Methods</p> <p>Study participants were diabetics from the Health Professionals Follow-Up Study (HPFS) and the Nurses' Health Study (NHS). We analyzed single nucleotide polymorphisms (SNPs) associated with cardiovascular pathophysiology (including <it>AGT1R </it>T573C, <it>AGT1R </it>A1166C, and <it>AGT </it>M235T) and presence of renal dysfunction (eGFR<60 ml/min/1.73 m²) or history of CHD.</p> <p>Results</p> <p>The <it>AGT1R </it>1166 C-allele was associated with eGFR<60 ml/min/1.73 m²(multivariable OR 1.63 [1.01, 2.65]) in the HPFS men (n = 733) and in the combined dataset (n = 1566) (OR 1.42 [1.02, 1.98]). The <it>AGT1R </it>1166 C-allele was also associated with CHD in men (OR 1.57 [1.10, 2.24]). In NHS women (n = 833), <it>AGT </it>235T-allele was associated with CHD (OR 1.72 [1.20, 2.47]). Removal of hypertension from the fully adjusted models did not influence results, suggesting that the associations may not be mediated by hypertension. There were significant interactions between sex and <it>AGT1R </it>1166 C-allele (p = 0.008) and <it>AGT </it>M235T (p = 0.03) in models for CHD. No significant associations were seen between <it>AGT1R </it>T573 C-allele and renal dysfunction or CHD.</p> <p>Conclusion</p> <p>Polymorphisms in <it>AGT1R </it>and <it>AGT </it>genes are associated with renal dysfunction and CHD in type 2 diabetes and further support the important role of the RAS in these complications. Sex may modify associations between <it>AGT1R </it>1166 C-allele and <it>AGT </it>235T and CHD in type 2 diabetes.</p