Plasmonic edge states: an electrostatic eigenmode description

We consider periodic arrangements of metal nanostructures and study the effect of periodicity on the localised surface plasmon resonance of the structures within an electrostatic eigenmode approximation. We show that within this limit, the collective surface plasmon resonances of the periodic structures can be expressed in terms of superpositions of the eigenmodes of uncoupled nanostructures that exhibit a standing--wave character delocalised across the entire periodic structure. The formalism derived successfully enables the design and accounts for the observation of plasmonic edge-states in periodic structures

Nonlinear feedback model attitude control using CCD in magnetic suspension system

A model attitude control system for a CCD camera magnetic suspension system is studied in this paper. In a recent work, a position and attitude sensing method was proposed. From this result, model position and attitude of a magnetic suspension system can be detected by generating digital outputs. Based on this achievement, a control system design using nonlinear feedback techniques for magnetic suspended model attitude control is proposed

Shigella flexneri utilize the spectrin cytoskeleton during invasion and comet tail generation

<p>Abstract</p> <p>Background</p> <p>The spectrin cytoskeleton is emerging as an important host cell target of enteric bacterial pathogens. Recent studies have identified a crucial role for spectrin and its associated proteins during key pathogenic processes of <it>Listeria monocytogenes </it>and <it>Salmonella </it>Typhimurium infections. Here we investigate the involvement of spectrin cytoskeletal components during the pathogenesis of the invasive pathogen <it>Shigella flexneri.</it></p> <p>Results</p> <p>Immunofluorescent microscopy reveals that protein 4.1 (p4.1), but not adducin or spectrin, is robustly recruited to sites of <it>S. flexneri </it>membrane ruffling during epithelial cell invasion. Through siRNA-mediated knockdowns, we identify an important role for spectrin and the associated proteins adducin and p4.1 during <it>S. flexneri </it>invasion. Following internalization, all three proteins are recruited to the internalized bacteria, however upon generation of actin-rich comet tails, we observed spectrin recruitment to those structures in the absence of adducin or p4.1.</p> <p>Conclusion</p> <p>These findings highlight the importance of the spectrin cytoskeletal network during <it>S. flexneri </it>pathogenesis and further demonstrate that pathogenic events that were once thought to exclusively recruit the actin cytoskeletal system require additional cytoskeletal networks.</p

Explaining Africa\u27s (Dis)Advantage

Africa’s economic performance has been widely viewed with pessimism. In this paper, firm-level data for around 80 countries are used to examine formal firm performance. Without controls, manufacturing African firms perform significantly worse than firms in other regions. They have lower productivity levels and growth rates, export less, and have lower investment rates. Once geography, political competition, and the business environment are controlled for, formal African firms lead in productivity levels and growth. Africa’s conditional advantage is higher in low-tech than in high-tech manufacturing, and exists in manufacturing but not in services. The key factors explaining Africa’s disadvantage at the firm level are lack of infrastructure, access to finance, and political competition

Loss of vesicular dopamine release precedes tauopathy in degenerative dopaminergic neurons in a Drosophila model expressing human tau.

While a number of genome-wide association studies have identified microtubule-associated protein tau as a strong risk factor for Parkinson's disease (PD), little is known about the mechanism through which human tau can predispose an individual to this disease. Here, we demonstrate that expression of human wild-type tau is sufficient to disrupt the survival of dopaminergic neurons in a Drosophila model. Tau triggers a synaptic pathology visualized by vesicular monoamine transporter-pHGFP that precedes both the age-dependent formation of tau-containing neurofibrillary tangle-like pathology and the progressive loss of DA neurons, thereby recapitulating the pathological hallmarks of PD. Flies overexpressing tau also exhibit progressive impairments of both motor and learning behaviors. Surprisingly, contrary to common belief that hyperphosphorylated tau could aggravate toxicity, DA neuron degeneration is alleviated by expressing the modified, hyperphosphorylated tau(E14). Together, these results show that impairment of VMAT-containing synaptic vesicle, released to synapses before overt tauopathy may be the underlying mechanism of tau-associated PD and suggest that correction or prevention of this deficit may be appropriate targets for early therapeutic intervention

The effect of a home-based strength training program on type 2 diabetes risk in obese Latino boys

This paper is designed to determine the effects of a home-based strength training (HBST) intervention on insulin sensitivity (SI), compensatory acute insulin response and β-cell function, body composition measures, and maximum strength in obese Latino boys. A total of 26 obese Latino males aged between 14 and 18 years were randomized to either a twice-weekly (n=15) or a control group (C; n=15) for 16 weeks. HBST for 16 weeks, composed of two 1-h sessions per week. Outcome measures were assessed pre-and post-intervention/control condition and included SI, acute insulin response to glucose (AIR) and disposition index (DI), fasting glucose, 2-h glucose, body composition using waist-hip circumferences, body mass index (BMI), dual energy X-ray absorptiometry (DEXA) scan, blood pressure, and strength by 1-repetition maximum. A repeated measures GLM was used to assess differences in changes in outcome measures, between the C and the HBST groups. There were no significant overall intervention effects on any of the outcome variables (p<0.05). These results suggest that an HBST does not improve SI, maximal strength or decrease adiposity in obese Latino boys

Myeloid Cell Sirtuin-1 Expression Does Not Alter Host Immune Responses to Gram-Negative Endotoxemia or Gram-Positive Bacterial Infection

The role of sirtuin-1 (SIRT1) in innate immunity, and in particular the influence of SIRT1 on antimicrobial defense against infection, has yet to be reported but is important to define since SIRT1 inhibitors are being investigated as therapeutic agents in the treatment of cancer, Huntington’s disease, and autoimmune diseases. Given the therapeutic potential of SIRT1 suppression, we sought to characterize the role of SIRT1 in host defense. Utilizing both pharmacologic methods and a genetic knockout, we demonstrate that SIRT1 expression has little influence on macrophage and neutrophil antimicrobial functions. Myeloid SIRT1 expression does not change mortality in gram-negative toxin-induced shock or gram-positive bacteremia, suggesting that therapeutic suppression of SIRT1 may be done safely without suppression of myeloid cell-specific immune responses to severe bacterial infections.American Asthma Foundation (Stephen Silberstein Senior Fellowship Awards

Role of hypoxia inducible factor-1α (HIF-1α) in innate defense against uropathogenic Escherichia coli infection

Uropathogenic E. coli (UPEC) is the primary cause of urinary tract infections (UTI) affecting approximately 150 million people worldwide. Here, we revealed the importance of transcriptional regulator hypoxia-inducible factor-1 α subunit (HIF-1α) in innate defense against UPEC-mediated UTI. The effects of AKB-4924, a HIF-1α stabilizing agent, were studied using human uroepithelial cells (5637) and a murine UTI model. UPEC adherence and invasion were significantly reduced in 5637 cells when HIF-1α protein was allowed to accumulate. Uroepithelial cells treated with AKB-4924 also experienced reduced cell death and exfoliation upon UPEC challenge. In vivo, fewer UPEC were recovered from the urine, bladders and kidneys of mice treated transurethrally with AKB-4924, whereas increased bacteria were recovered from bladders of mice with a HIF-1α deletion. Bladders and kidneys of AKB-4924 treated mice developed less inflammation as evidenced by decreased pro-inflammatory cytokine release and neutrophil activity. AKB-4924 impairs infection in uroepithelial cells and bladders, and could be correlated with enhanced production of nitric oxide and antimicrobial peptides cathelicidin and β-defensin-2. We conclude that HIF-1α transcriptional regulation plays a key role in defense of the urinary tract against UPEC infection, and that pharmacological HIF-1α boosting could be explored further as an adjunctive therapy strategy for serious or recurrent UTI

Primate immunodeficiency virus Vpx and Vpr counteract transcriptional repression of proviruses by the HUSH complex [preprint]

Drugs that inhibit HIV-1 replication and prevent progression to AIDS do not eliminate HIV-1 proviruses from the chromosomes of long-lived CD4+ memory T cells. To escape eradication by these antiviral drugs, or by the host immune system, HIV-1 exploits poorly defined host factors that silence provirus transcription. These same factors, though, must be overcome by all retroviruses, including HIV-1 and other primate immunodeficiency viruses, in order to activate provirus transcription and produce new virus. Here we show that Vpx and Vpr, proteins from a wide range of primate immunodeficiency viruses, activate provirus transcription in human CD4+ T cells. Provirus activation required the DCAF1 adaptor that links Vpx and Vpr to the CUL4A/B ubiquitin ligase complex, but did not require degradation of SAMHD1, a well-characterized target of Vpx and Vpr. A loss-of-function screen for transcription silencing factors that mimic the effect of Vpx on provirus silencing identified all components of the Human Silencing Hub (HUSH) complex, FAM208A (TASOR/RAP140), MPHOSPH8 (MPP8), PPHLN1 (PERIPHILIN), and MORC2. Vpx associated with the HUSH complex components and decreased steady-state levels of these proteins in a DCAF-dependent manner. Finally, vpx and FAM208A knockdown accelerated HIV-1 and SIVMAC replication kinetics in CD4+ T cells to a similar extent, and HIV-2 replication required either vpx or FAM208A disruption. These results demonstrate that the HUSH complex restricts transcription of primate immunodeficiency viruses and thereby contributes to provirus latency. To counteract this restriction and activate provirus expression, primate immunodeficiency viruses encode Vpx and Vpr proteins that degrade HUSH complex components

Pharmacological and Toxicological Properties of the Potent Oral γ-Secretase Modulator BPN-15606.

Alzheimer's disease (AD) is characterized neuropathologically by an abundance of 1) neuritic plaques, which are primarily composed of a fibrillar 42-amino-acid amyloid-β peptide (Aβ), as well as 2) neurofibrillary tangles composed of aggregates of hyperphosporylated tau. Elevations in the concentrations of the Aβ42 peptide in the brain, as a result of either increased production or decreased clearance, are postulated to initiate and drive the AD pathologic process. We initially introduced a novel class of bridged aromatics referred tγ-secretase modulatoro as γ-secretase modulators that inhibited the production of the Aβ42 peptide and to a lesser degree the Aβ40 peptide while concomitantly increasing the production of the carboxyl-truncated Aβ38 and Aβ37 peptides. These modulators potently lower Aβ42 levels without inhibiting the γ-secretase-mediated proteolysis of Notch or causing accumulation of carboxyl-terminal fragments of APP. In this study, we report a large number of pharmacological studies and early assessment of toxicology characterizing a highly potent γ-secretase modulator (GSM), (S)-N-(1-(4-fluorophenyl)ethyl)-6-(6-methoxy-5-(4-methyl-1H-imidazol-1-yl)pyridin-2-yl)-4-methylpyridazin-3-amine (BPN-15606). BPN-15606 displayed the ability to significantly lower Aβ42 levels in the central nervous system of rats and mice at doses as low as 5-10 mg/kg, significantly reduce Aβ neuritic plaque load in an AD transgenic mouse model, and significantly reduce levels of insoluble Aβ42 and pThr181 tau in a three-dimensional human neural cell culture model. Results from repeat-dose toxicity studies in rats and dose escalation/repeat-dose toxicity studies in nonhuman primates have designated this GSM for 28-day Investigational New Drug-enabling good laboratory practice studies and positioned it as a candidate for human clinical trials