Magnetic Response of Magnetospirillum Gryphiswaldense

In this study we modelled and measured the U-turn trajectories of individual magnetotactic bacteria under the application of rotating magnetic fields, ranging in ampitude from 1 to 12 mT. The model is based on the balance between rotational drag and magnetic torque. For accurate verification of this model, bacteria were observed inside 5 m tall microfluidic channels, so that they remained in focus during the entire trajectory. From the analysis of hundreds of trajectories and accurate measurements of bacteria and magnetosome chain dimensions, we confirmed that the model is correct within measurement error. The resulting average rate of rotation of Magnetospirillum Gryphiswaldense is 0.74 +- 0.03 rad/mTs.Comment: 17 pages, 12 figure

High proton conductivity in cyanide-bridged metal-organic frameworks: understanding the role of water

We investigate and discuss the proton conductivity properties of the cyanide-bridged metal–organic framework (MOF) [Nd(mpca)2Nd(H2O)6Mo(CN)8]·nH2O (where mpca is 5-methyl-2-pyrazinecarboxylate). This MOF is one of an exciting class of cyanide-bridged materials that can combine porosity with magnetism, luminescence, and proton conductivity. Specifically, we show that this material features highly hydrophilic open channels filled with water molecules. They enable a high proton conductivity, as much as 10−3 S cm−1. A rich hydrogen-bonding network, formed by the ligands' carboxylate groups with both coordinated and lattice water molecules, facilitates this high proton conductivity. Combined thermogravimetric studies, FTIR spectroscopy and PXRD analysis show that upon heating at 80 °C, the lattice water molecules are removed without any change in the framework. Further heating at 130 °C results in a partial removal of the coordinated water molecules, while still retaining the original framework. These activated MOFs shows an increasing conductivity from ∼10−9 S cm−1 to ∼10−3 S cm−1 when the relative humidity increases from 0% to 98%. Our studies show that the increase in proton conductivity is correlated with the re-hydration of the framework with lattice water molecules. The Arrhenius activation energy for the proton conductivity process is low (Ea = 37 kJ mol−1), indicating that the protons “hop” through the channels following the Grotthuss mechanism. The fact that this MOF is remarkably stable both under high humidity conditions and at relatively high temperatures (up to 130 °C) makes it a good candidate for real-life applications

Role of transport performance on neuron cell morphology

The compartmental model is a basic tool for studying signal propagation in neurons, and, if the model parameters are adequately defined, it can also be of help in the study of electrical or fluid transport. Here we show that the input resistance, in different networks which simulate the passive properties of neurons, is the result of an interplay between the relevant conductances, morphology and size. These results suggest that neurons must grow in such a way that facilitates the current flow. We propose that power consumption is an important factor by which neurons attain their final morphological appearance.Comment: 9 pages with 3 figures, submitted to Neuroscience Letter

Proteome-based plasma biomarkers for Alzheimer's disease

Alzheimer's disease is a common and devastating disease for which there is no readily available biomarker to aid diagnosis or to monitor disease progression. Biomarkers have been sought in CSF but no previous study has used two-dimensional gel electrophoresis coupled with mass spectrometry to seek biomarkers in peripheral tissue. We performed a case-control study of plasma using this proteomics approach to identify proteins that differ in the disease state relative to aged controls. For discovery-phase proteomics analysis, 50 people with Alzheimer's dementia were recruited through secondary services and 50 normal elderly controls through primary care. For validation purposes a total of 511 subjects with Alzheimer's disease and other neurodegenerative diseases and normal elderly controls were examined. Image analysis of the protein distribution of the gels alone identifies disease cases with 56% sensitivity and 80% specificity. Mass spectrometric analysis of the changes observed in two-dimensional electrophoresis identified a number of proteins previously implicated in the disease pathology, including complement factor H (CFH) precursor and α-2-macroglobulin (α- 2M). Using semi-quantitative immunoblotting, the elevation of CFH and α- 2M was shown to be specific for Alzheimer's disease and to correlate with disease severity although alternative assays would be necessary to improve sensitivity and specificity. These findings suggest that blood may be a rich source for biomarkers of Alzheimer's disease and that CFH, together with other proteins such as α- 2M may be a specific markers of this illness. © 2006 The Author(s).link_to_subscribed_fulltex

Novel role for the innate immune receptor toll-like receptor 4 (TLR4) in the regulation of the wnt signaling pathway and photoreceptor apoptosis

Recent evidence has implicated innate immunity in regulating neuronal survival in the brain during stroke and other neurodegenerations. Photoreceptors are specialized light-detecting neurons in the retina that are essential for vision. In this study, we investigated the role of the innate immunity receptor TLR4 in photoreceptors. TLR4 activation by lipopolysaccharide (LPS) significantly reduced the survival of cultured mouse photoreceptors exposed to oxidative stress. With respect to mechanism, TLR4 suppressed Wnt signaling, decreased phosphorylation and activation of the Wnt receptor LRP6, and blocked the protective effect of the Wnt3a ligand. Paradoxically, TLR4 activation prior to oxidative injury protected photoreceptors, in a phenomenon known as preconditioning. Expression of TNFα and its receptors TNFR1 and TNFR2 decreased during preconditioning, and preconditioning was mimicked by TNFα antagonists, but was independent of Wnt signaling. Therefore, TLR4 is a novel regulator of photoreceptor survival that acts through the Wnt and TNFα pathways. © 2012 Yi et al

Visualizing the Anthropocene dialectically: Jessica Woodworth and Peter Brosens’ eco-crisis trilogy

The ambition of this article is to propose a way of visualizing the Anthropocene dialectically. As suggested by the Dutch atmospheric chemist Paul Crutzen and the professor of biology Eugene F. Stoermer, the term Anthropocene refers to a historical period in which humankind has turned into a geological force that transforms the natural environment in such a way that it is hard to distinguish between the human and the natural world. Crutzen and Stoermer explain that the Anthropocene has begun after the Holocene, the geological epoch that followed the last ice age and lasted until the industrial revolution. Drawing on a number of figures such as the “tenfold” increase in urbanisation, the extreme transformation of land surface by human action, the use of more than 50% of all accessible fresh water by humans, and the massive increase in greenhouse emissions, Crutzen and Stoermer conclude that the term Anthropocene describes aptly mankind's influence on ecological and geological cycles (Crutzen & Stoermer, 2000, p.17). The wager of this article is that we need to identify ways to visualize the Anthropocene dialectically and I proceed to do so using as a case study Jessica Woodworth's and Peter Brosen's trilogy on the conflict between humans and nature, which consists of Khadak (2006), Altiplano (2009), and The Fifth Season (La Cinquième Saison, 2012)

Queen Elizabeth’s Leadership Abroad: The Netherlands in the 1570s

In 1576, after Edmund Grindal, archbishop of Canterbury, presumed to lecture Queen Elizabeth on the importance of preaching and on her duty to listen to such lectures, his influence diminished precipitously, and leadership of the established English church fell to Bishop Aylmer. Grindal’s friends on the queen’s Privy Council, “forward” Calvinists (or ultra-Protestants), were powerless to save him from the consequences of his indiscretion, which damaged the ultras’ other initiatives’ chances of success. This paper concerns one of those initiatives. From the late 1560s, they urged their queen “actively” to intervene in the Dutch wars. They collaborated with Calvinists on the Continent who befriended Prince William of Orange and who hoped to help him hold together a coalition of religiously reformed and Roman Catholic insurgents in the seventeen provinces of the Low Countries. The English ultra-Protestants would have their government send money, munitions, and men in arms to the Netherlands, to tip the balance against viceroys sent by King Philip II of Spain. Grindal’s setback undermined the English Calvinists’ efforts to form an Anglo-Dutch alliance which, they assumed, would boost the prospects for an international Protestant league. Yet Elizabeth did assist the Dutch as they wrestled with decisions forced on them by developments in the Netherlands during the 1570s, and she did so more consistently and more cleverly than many historians of Tudor diplomacy have thought. Two competing assessments determine the way questions are formulated in the study of the queen’s and regime’s Dutch diplomacy. The general consensus is that she was indecisive and inconsistent. Paul Hammer characterizes Elizabeth’s responses to the crises in the Low Countries as a “zigzag of different” (“even contradictory”) maneuvers. Wallace McCaffrey and R. B. Wernham agree that England’s “hesitations and gyrations” do not pass as coherent, creditable policy. Charles Wilson scolds Elizabeth for being timid and tepid--incapable of enthusiasm for “a great cause.” But David J.B. Trim’s striking counterthrust depicts the queen’s overtures to Netherlanders as part of her courageous – and “confessionally driven” – foreign policy; Trim replaces “hesitation” and “zigzag” with a coherent “Protestant programme of action prioritized by the Elizabethan government” with the aim of improving prospects for “Calvinist internationalism.” What follows is an alternative to all these characterizations, one that, as noted, finds evidence for greater consistency and coherence in Elizabeth’s leadership and less confessional “drive.” That she would have been uneasy around religious extremists ought not to astonish us; her father’s, step-brother’s, and step-sister’s reigns as well as the start of her own were disturbed by zealous subjects, who were bent on shoring up or dismantling the realm’s religious settlements

An integrated workflow for robust alignment and simplified quantitative analysis of NMR spectrometry data

<p>Abstract</p> <p>Background</p> <p>Nuclear magnetic resonance spectroscopy (NMR) is a powerful technique to reveal and compare quantitative metabolic profiles of biological tissues. However, chemical and physical sample variations make the analysis of the data challenging, and typically require the application of a number of preprocessing steps prior to data interpretation. For example, noise reduction, normalization, baseline correction, peak picking, spectrum alignment and statistical analysis are indispensable components in any NMR analysis pipeline.</p> <p>Results</p> <p>We introduce a novel suite of informatics tools for the quantitative analysis of NMR metabolomic profile data. The core of the processing cascade is a novel peak alignment algorithm, called hierarchical Cluster-based Peak Alignment (CluPA). The algorithm aligns a target spectrum to the reference spectrum in a top-down fashion by building a hierarchical cluster tree from peak lists of reference and target spectra and then dividing the spectra into smaller segments based on the most distant clusters of the tree. To reduce the computational time to estimate the spectral misalignment, the method makes use of Fast Fourier Transformation (FFT) cross-correlation. Since the method returns a high-quality alignment, we can propose a simple methodology to study the variability of the NMR spectra. For each aligned NMR data point the ratio of the between-group and within-group sum of squares (BW-ratio) is calculated to quantify the difference in variability between and within predefined groups of NMR spectra. This differential analysis is related to the calculation of the F-statistic or a one-way ANOVA, but without distributional assumptions. Statistical inference based on the BW-ratio is achieved by bootstrapping the null distribution from the experimental data.</p> <p>Conclusions</p> <p>The workflow performance was evaluated using a previously published dataset. Correlation maps, spectral and grey scale plots show clear improvements in comparison to other methods, and the down-to-earth quantitative analysis works well for the CluPA-aligned spectra. The whole workflow is embedded into a modular and statistically sound framework that is implemented as an R package called "speaq" ("spectrum alignment and quantitation"), which is freely available from <url>http://code.google.com/p/speaq/</url>.</p

Physical Activity and Cardiac Function in Long-Term Breast Cancer Survivors:A Cross-Sectional Study

Background: Higher levels of physical activity are associated with a lower risk of cardiovascular disease in the general population. Whether the same holds for women who underwent treatment for breast cancer is unclear. Objectives: The aim of this study was to evaluate the association between physical activity in a typical week in the past 12 months and cardiac dysfunction in breast cancer survivors. Methods: We used data from a cohort of breast cancer survivors who were treated at ages 40 to 50 years (N = 559). The association between physical activity and global longitudinal strain (GLS) and left ventricular ejection fraction (LVEF) was evaluated using both linear and modified Poisson regression analyses adjusted for relevant confounders. Results: In total, 559 breast cancer survivors were included, with median age of 55.5 years and a median time since treatment of 10.2 years. GLS was less favorable in inactive survivors (−17.1%) than in moderately inactive (−18.4%), moderately active (−18.2%), and active survivors (−18.5%), with an adjusted significant difference for active versus inactive survivors (β = −1.31; 95% CI: −2.55 to −0.06)). Moderately active (n = 57/130) and active survivors (n = 87/124) had significantly lower risks of abnormal GLS (defined as >−18%) compared with inactive survivors (n = 17/26) (RR: 0.65 [95% CI: 0.45-0.94] and RR: 0.61 [95% CI: 0.43-0.87], respectively). LVEF, in normal ranges in all activity categories, was not associated with physical activity. Conclusions: In long-term breast cancer survivors, higher physical activity levels were associated with improved GLS but not LVEF, with the relatively largest benefit for doing any activity versus none. This finding suggests that increasing physical activity may contribute to cardiovascular health benefits, especially in inactive survivors