Modelling of the pulsatile blood flow in an arterial tree of retinal vasculature

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.The paper presents a numerical investigation of pulsatile blood flow in arterial vasculatures of a mouse retina using a Womersley model incorporating an appropriate outlet boundary impedance at the end of the terminal vessels of the arterial tree (pre-capillary arterioles). The mouse retinal flatmount was prepared for confocal microscopy and the morphometric information of the vasculature was obtained from the confocal images. The pulsatile analysis focused on one of the arterial trees in the retinal vasculature. We included the in vivo viscosity evaluated from the mathematical models of Fahraues-Lindquist effect and the plasma skimming effect in the microcirculation. Comparative investigations of the pulsatile circulation were carried out for cases of constant viscosity, in vivo viscosity, zero and non-zero outlet boundary impedance. In addition, the dependency of the oscillating input impedance at the inlet of the arterial trees on angular frequencies of the oscillation and vessel elasticises was also studied. The study shows the pulsatile blood flow prediction is largely influenced by the outlet boundary impedance. The oscillating input impedance at the inlet of the arterial tree is also found to be significantly dependent on the angular frequency and the Young modulus of the vessel segment

Magnetic quantum phase transition of cold atoms in an optical lattice

We propose a scheme to investigate the magnetic phase transition of cold atoms confined in an optical lattice. We also demonstrate how to get coupled two-leg spin ladders which display a phase transition from a spin liquid to magnetic ordered state in two-dimensional optical lattice. An experimental protocol is further designed for observing this phenomenon. © 2007 The American Physical Society.published_or_final_versio

Is objective and accurate cognitive assessment across the menstrual cycle possible? A feasibility study

YesOBJECTIVES: Variation in plasma hormone levels influences the neurobiology of brain regions involved in cognition and emotion processing. Fluctuations in hormone levels across the menstrual cycle could therefore alter cognitive performance and wellbeing; reports have provided conflicting results, however. The aim of this study was to assess whether objective assessment of cognitive performance and self-reported wellbeing during the follicular and luteal phases of the menstrual cycle is feasible and investigate the possible reasons for variation in effects previously reported. METHODS: The Cambridge Neuropsychological Test Automated Battery and Edinburgh Postnatal Depression Scale were used to assess the cognitive performance and wellbeing of 12 women. Data were analysed by self-reported and hormone-estimated phases of the menstrual cycle. RESULTS: Recruitment to the study and assessment of cognition and wellbeing was without issue. Plasma hormone and peptide estimation showed substantial individual variation and suggests inaccuracy in self-reported menstrual phase estimation. CONCLUSION: Objective assessment of cognitive performance and self-assessed wellbeing across the menstrual cycle is feasible. Grouping data by hormonal profile rather by self-reported phase estimation may influence phase-mediated results. Future studies should use plasma hormone and peptide profiles to estimate cycle phase and group data for analyses

Overexpression of ZFX confers self-renewal and chemoresistance properties in hepatocellular carcinoma

postprin

A Randomized Controlled Trial of Angiotensin-Converting Enzyme Inhibition for Skeletal Muscle Dysfunction in COPD

BACKGROUND: Skeletal muscle impairment is a recognized complication of COPD, predicting mortality in severe disease. Increasing evidence implicates the renin-angiotensin system in control of muscle phenotype. We hypothesized that angiotensin-converting enzyme (ACE) inhibition would improve quadriceps function and exercise performance in COPD. METHODS: This double-blind, randomized placebo-controlled trial investigated the effect of the ACE inhibitor, fosinopril, on quadriceps function in patients with COPD with quadriceps weakness. Primary outcomes were change in quadriceps endurance and atrophy signaling at 3 months. Quadriceps maximum voluntary contraction (QMVC), mid-thigh CT scan of the cross-sectional area (MTCSA), and incremental shuttle walk distance (ISWD) were secondary outcomes. RESULTS: Eighty patients were enrolled (mean [SD], 65 [8] years, FEV1 43% [21%] predicted, 53% men). Sixty-seven patients (31 fosinopril, 36 placebo) completed the trial. The treatment group demonstrated a significant reduction in systolic BP (Δ−10.5 mm Hg; 95% CI, −19.9 to −1.1; P = .03) and serum ACE activity (Δ−20.4 IU/L; 95% CI, −31.0 to −9.8; P < .001) compared with placebo. No significant between-group differences were observed in the primary end points of quadriceps endurance half-time (Δ0.5 s; 95% CI, −13.3-14.3; P = .94) or atrogin-1 messenger RNA expression (Δ−0.03 arbitrary units; 95% CI, −0.32-0.26; P = .84). QMVC improved in both groups (fosinopril: Δ1.1 kg; 95% CI, 0.03-2.2; P = .045 vs placebo: Δ3.6 kg; 95% CI, 2.1-5.0; P < .0001) with a greater increase in the placebo arm (between-group, P = .009). No change was shown in the MTCSA (P = .09) or ISWD (P = .51). CONCLUSIONS: This randomized controlled trial found that ACE inhibition, using fosinopril for 3 months, did not improve quadriceps function or exercise performance in patients with COPD with quadriceps weakness

Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents

Background Coffee and tea consumption was hypothesized to interact with variants of vitamin D-receptor polymorphisms, but limited evidence exists. Here we determine for the first time whether increased coffee and tea consumption affects circulating levels of 25-hydroxyvitamin D in a cohort of Saudi adolescents. Methods A total of 330 randomly selected Saudi adolescents were included. Anthropometrics were recorded and fasting blood samples were analyzed for routine analysis of fasting glucose, lipid levels, calcium, albumin and phosphorous. Frequency of coffee and tea intake was noted. 25-hydroxyvitamin D levels were measured using enzyme-linked immunosorbent assays. Results Improved lipid profiles were observed in both boys and girls, as demonstrated by increased levels of HDL-cholesterol, even after controlling for age and BMI, among those consuming 9–12 cups of coffee/week. Vitamin D levels were significantly highest among those consuming 9–12 cups of tea/week in all subjects (p-value 0.009) independent of age, gender, BMI, physical activity and sun exposure. Conclusion This study suggests a link between tea consumption and vitamin D levels in a cohort of Saudi adolescents, independent of age, BMI, gender, physical activity and sun exposure. These findings should be confirmed prospectively

An enormous sulfur isotope excursion indicates marine anoxia during the end-Triassic mass extinction

The role of ocean anoxia as a cause of the end-Triassic marine mass extinction is widely debated. Here, we present carbonate-associated sulfate δ³⁴S data from sections spanning the Late Triassic–Early Jurassic transition, which document synchronous large positive excursions on a global scale occurring in ~50 thousand years. Biogeochemical modeling demonstrates that this S isotope perturbation is best explained by a fivefold increase in global pyrite burial, consistent with large-scale development of marine anoxia on the Panthalassa margin and northwest European shelf. This pyrite burial event coincides with the loss of Triassic taxa seen in the studied sections. Modeling results also indicate that the pre-event ocean sulfate concentration was low (<1 millimolar), a common feature of many Phanerozoic deoxygenation events. We propose that sulfate scarcity preconditions oceans for the development of anoxia during rapid warming events by increasing the benthic methane flux and the resulting bottom-water oxygen demand

Sex-biased parental care and sexual size dimorphism in a provisioning arthropod

The diverse selection pressures driving the evolution of sexual size dimorphism (SSD) have long been debated. While the balance between fecundity selection and sexual selection has received much attention, explanations based on sex-specific ecology have proven harder to test. In ectotherms, females are typically larger than males, and this is frequently thought to be because size constrains female fecundity more than it constrains male mating success. However, SSD could additionally reflect maternal care strategies. Under this hypothesis, females are relatively larger where reproduction requires greater maximum maternal effort – for example where mothers transport heavy provisions to nests. To test this hypothesis we focussed on digger wasps (Hymenoptera: Ammophilini), a relatively homogeneous group in which only females provision offspring. In some species, a single large prey item, up to 10 times the mother’s weight, must be carried to each burrow on foot; other species provide many small prey, each flown individually to the nest. We found more pronounced female-biased SSD in species where females carry single, heavy prey. More generally, SSD was negatively correlated with numbers of prey provided per offspring. Females provisioning multiple small items had longer wings and thoraxes, probably because smaller prey are carried in flight. Despite much theorising, few empirical studies have tested how sex-biased parental care can affect SSD. Our study reveals that such costs can be associated with the evolution of dimorphism, and this should be investigated in other clades where parental care costs differ between sexes and species

Profiles of physical, emotional and psychosocial wellbeing in the Lothian birth cohort 1936

<p>Abstract</p> <p>Background</p> <p>Physical, emotional, and psychosocial wellbeing are important domains of function. The aims of this study were to explore the existence of separable groups among 70-year olds with scores representing physical function, perceived quality of life, and emotional wellbeing, and to characterise any resulting groups using demographic, personality, cognition, health and lifestyle variables.</p> <p>Methods</p> <p>We used latent class analysis (LCA) to identify possible groups.</p> <p>Results</p> <p>Results suggested there were 5 groups. These included High (n = 515, 47.2% of the sample), Average (n = 417, 38.3%), and Poor Wellbeing (n = 37, 3.4%) groups. The two other groups had contrasting patterns of wellbeing: one group scored relatively well on physical function, but low on emotional wellbeing (Good Fitness/ Low Spirits,n = 60, 5.5%), whereas the other group showed low physical function but relatively well emotional wellbeing (Low Fitness/Good Spirits, n = 62, 5.7%). Salient characteristics that distinguished all the groups included smoking and drinking behaviours, personality, and illness.</p> <p>Conclusions</p> <p>Despite there being some evidence of these groups, the results also support a largely one-dimensional construct of wellbeing in old age—for the domains assessed here—though with some evidence that some individuals have uneven profiles.</p