486 research outputs found
A Cross-Sectional Study of People with Epilepsy and Neurocysticercosis in Tanzania: Clinical Characteristics and Diagnostic Approaches.
Neurocysticercosis (NCC) is a major cause of epilepsy in regions where pigs are free-ranging and hygiene is poor. Pork production is expected to increase in the next decade in sub-Saharan Africa, hence NCC will likely become more prevalent. In this study, people with epilepsy (PWE, n=212) were followed up 28.6 months after diagnosis of epilepsy. CT scans were performed, and serum and cerebrospinal fluid (CSF) of selected PWE were analysed. We compared the demographic data, clinical characteristics, and associated risk factors of PWE with and without NCC. PWE with NCC (n=35) were more likely to be older at first seizure (24.3 vs. 16.3 years, p=0.097), consumed more pork (97.1% vs. 73.6%, p=0.001), and were more often a member of the Iraqw tribe (94.3% vs. 67.8%, p=0.005) than PWE without NCC (n=177). PWE and NCC who were compliant with anti-epileptic medications had a significantly higher reduction of seizures (98.6% vs. 89.2%, p=0.046). Other characteristics such as gender, seizure frequency, compliance, past medical history, close contact with pigs, use of latrines and family history of seizures did not differ significantly between the two groups. The number of NCC lesions and active NCC lesions were significantly associated with a positive antibody result. The electroimmunotransfer blot, developed by the Centers for Disease Control and Prevention, was more sensitive than a commercial western blot, especially in PWE and cerebral calcifications. This is the first study to systematically compare the clinical characteristics of PWE due to NCC or other causes and to explore the utility of two different antibody tests for diagnosis of NCC in sub-Saharan Africa
Scope for Credit Risk Diversification
This paper considers a simple model of credit risk and derives the limit distribution of losses under different assumptions regarding the structure of systematic risk and the nature of exposure or firm heterogeneity. We derive fat-tailed correlated loss distributions arising from Gaussian risk factors and explore the potential for risk diversification. Where possible the results are generalised to non-Gaussian distributions. The theoretical results indicate that if the firm parameters are heterogeneous but come from a common distribution, for sufficiently large portfolios there is no scope for further risk reduction through active portfolio management. However, if the firm parameters come from different distributions, then further risk reduction is possible by changing the portfolio weights. In either case, neglecting parameter heterogeneity can lead to underestimation of expected losses. But, once expected losses are controlled for, neglecting parameter heterogeneity can lead to overestimation of risk, whether measured by unexpected loss or value-at-risk
Microwave-assisted synthesis of Pd nanoparticles supported on Fe 3O4, Co3O4, and Ni(OH)2 nanoplates and catalysis application for CO oxidation
In this paper, we report a simple, versatile, and rapid method for the synthesis of Pd nanoparticle catalysts supported on Fe3O4, Co3O4, and Ni (OH)2 nanoplates via microwave irradiation. The important advantage of microwave dielectric heating over convective heating is that the reactants can be added at room temperature (or slightly higher temperatures) without the need for high-temperature injection. Furthermore, the method can be used to synthesize metal nanoparticle catalysts supported on metal oxide nanoparticles in one step. We also demonstrate that the catalyst-support interaction plays an important role in the low temperature oxidation of CO. The current results reveal that the Pd/Co3O4 catalyst has particularly high activity for CO oxidation as a result of the strong interaction between the Pd nanoparticles and the Co 3O4 nanoplates. Optimizations of the size, composition, and shape of these catalysts could provide a new family of efficient nanocatalysts for the low temperature oxidation of CO. © 2014 Springer Science+Business Media
Effects of a Pyrrole-Based, Microtubule-Depolymerizing Compound on RAW 264.7 Macrophages
RAW 264.7 murine macrophages were exposed to the pyrrole-based compound 3,5-Dibromo-4-(3,4-dimethoxyphenyl)-1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14), which is a known microtubule depolymerizing agent with antitumor activity [1,2,3]. In this study exposure to JG-03-14 reduced the production of pro-inflammatory molecules by macrophages activated with lipopolysaccharide (LPS). Treatment with the pyrrole-based compound decreased the concentration of tumor necrosis factor-α (TNF-α) and nitric oxide (NO) released from the macrophages. Exposure to JG-03-14 also decreased TNF-α mRNA expression levels and the protein expression levels of inducible nitric oxide synthase (iNOS), the enzyme responsible for NO production in the activated macrophages. Furthermore, JG-03-14 treatment significantly changed the degradation profile of IκB-β, an inhibitor of the NF-κB transcription factor, which suggests that JG-03–14 may attenuate the activation of the LPS-induced NF-κB signaling pathway needed to produce the pro-inflammatory mediators. We conclude that JG-03-14 possesses anti-inflammatory properties
Pd-Fe3O4/RGO: a Highly Active and Magnetically Recyclable Catalyst for Suzuki Cross Coupling Reaction using a Microfluidic Flow Reactor
There are several crucial issues that need to be addressed in the field of applied catalysis. These issues are not only related to harmful environmental impact but also include process safety concerns, mass and heat transfer limitations, selectivity, high pressure, optimizing reaction conditions, scale-up issues, reproducibility, process reliability, and catalyst deactivation and recovery. Many of these issues could be solved by adopting the concept of micro-reaction technology and flow chemistry in the applied catalysis field. A microwave assisted reduction technique has been used to prepare well dispersed, highly active Pd/Fe3O4 nanoparticles supported on reduced graphene oxide nanosheets (Pd-Fe3O4/RGO), which act as a unique catalyst for Suzuki cross coupling reactions due to the uniform dispersion of palladium nanoparticles throughout the surface of the magnetite - RGO support. The Pd-Fe3O4/RGO nanoparticles have been shown to exhibit extremely high catalytic activity for Suzuki cross coupling reactions under both batch and continuous reaction conditions. This paper reported a reliable method for Suzuki cross-coupling reaction of 4-bromobenzaldehyde using magnetically recyclable Pd/Fe3O4 nanoparticles supported on RGO nanosheets in a microfluidic-based high throughput flow reactor. Organic synthesis can be performed under high pressure and temperature by using a stainless steel micro tubular flow reactor under continuous flow reaction conditions. Optimizing the reaction conditions was performed via changing several parameters including temperature, pressure, and flow rate. Generally, a scalable flow technique by optimizing the reaction parameters under high-temperature and continuous reaction conditions could be successfully developed
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Risk perception of women during high risk pregnancy: A systematic review
Risk perception in women with high risk pregnancies can affect their attitude to medical care and therefore influence the wellbeing of mother and baby. This article reviews quantitative measures of risk perception in women with high risk pregnancies. A systematic search of eight electronic databases was conducted. Additional articles were obtained through searching references of identified articles. Seven studies were identified that reported quantitative measures of risk perception in relation to high risk pregnancy. The main findings were that women with high risk pregnancies perceive themselves and the pregnancies to be at risk. However, mean risk scores consistently fall below the midpoint on risk perception measures suggesting women do not perceive this risk as extreme. Women with high risk pregnancies consistently rated their risk as being greater than that of women with low risk pregnancies. Results were inconsistent for the association between women's risk perception and that of healthcare professionals. Women with higher socio-economic status were more likely to be concerned about risk, although lower socio-economic status is associated with increased risk in pregnancy. There was a consistent association between high risk pregnancy and higher levels of anxiety. This review indicates that women at high risk during pregnancy do not perceive this risk to be extreme and that there is poor agreement between women's and healthcare professionals’ perceptions of risk. This is likely to have implications for medical care and pregnancy outcomes
Interaction of microtubules and actin during the post-fusion phase of exocytosis
Exocytosis is the intracellular trafficking step where a secretory vesicle fuses with the plasma membrane to release vesicle content. Actin and microtubules both play a role in exocytosis; however, their interplay is not understood. Here we study the interaction of actin and microtubules during exocytosis in lung alveolar type II (ATII) cells that secrete surfactant from large secretory vesicles. Surfactant extrusion is facilitated by an actin coat that forms on the vesicle shortly after fusion pore opening. Actin coat compression allows hydrophobic surfactant to be released from the vesicle. We show that microtubules are localized close to actin coats and stay close to the coats during their compression. Inhibition of microtubule polymerization by colchicine and nocodazole affected the kinetics of actin coat formation and the extent of actin polymerisation on fused vesicles. In addition, microtubule and actin cross-linking protein IQGAP1 localized to fused secretory vesicles and IQGAP1 silencing influenced actin polymerisation after vesicle fusion. This study demonstrates that microtubules can influence actin coat formation and actin polymerization on secretory vesicles during exocytosis
Acidic Extracellular pH Promotes Activation of Integrin αvβ3
Acidic extracellular pH is characteristic of the cell microenvironment in several important physiological and pathological contexts. Although it is well established that acidic extracellular pH can have profound effects on processes such as cell adhesion and migration, the underlying molecular mechanisms are largely unknown. Integrin receptors physically connect cells to the extracellular matrix, and are thus likely to modulate cell responses to extracellular conditions. Here, we examine the role of acidic extracellular pH in regulating activation of integrin [alpha]v[beta]3. Through computational molecular dynamics simulations, we find that acidic extracellular pH promotes opening of the [alpha]v[beta]3 headpiece, indicating that acidic pH can thereby facilitate integrin activation. This prediction is consistent with our flow cytometry and atomic force microscope-mediated force spectroscopy assays of integrin [alpha]v[beta]3 on live cells, which both demonstrate that acidic pH promotes activation at the intact cell surface. Finally, quantification of cell morphology and migration measurements shows that acidic extracellular pH affects cell behavior in a manner that is consistent with increased integrin activation. Taken together, these computational and experimental results suggest a new and complementary mechanism of integrin activation regulation, with associated implications for cell adhesion and migration in regions of altered pH that are relevant to wound healing and cancer.National Institute of Biomedical Imaging and Bioengineering (U.S.) (Award Number T32EB006348)Massachusetts Institute of Technology (Collamore-Rogers Fellowship)National Institutes of Health (U.S.) (NIH Cell Migration Consortium Grant U54-GM069668)National Science Foundation (U.S.) (CAREER Award)Singapore-MIT Alliance for Research and Technology (BioSystem and Micromechanics (BioSyM) Interdisciplinary Research Group
The Continuous Synthesis Of Pd Supported On Fe3O4 Nanoparticles: A Highly Effective And Magnetic Catalyst For CO Oxidation
We report a facile approach used for the simultaneous reduction and synthesis of a well dispersed magnetically separable palladium nanoparticle supported on magnetite (Pd/Fe3O4 nanoparticles) via continuous flow synthesis under microwave irradiation conditions, using a Wave Craft\u27s microwave flow reactor commercially known as Arrhenius One, which can act as a unique process for the synthesis of highly active catalysts for carbon monoxide (CO) oxidation catalysis. The prepared catalysts are magnetic, which is an advantage in the separation process of the catalyst from the reaction medium. The separation process is achieved by applying a strong external magnetic field which makes the separation process easy, reliable, and environmentally friendly. Hydrazine hydrate was used as the reducing agent under continuous flow reaction conditions. The investigated catalysis data revealed that palladium supported on iron oxide catalyst synthesized by continuous flow microwave irradiation conditions showed remarkable high catalytic activity towards CO oxidation compared to the ones that were prepared by batch reaction conditions under the same experimental conditions. This could be attributed to the high degree of dispersion and concentration ratio of the Pd nanoparticles dispersed on the surface of magnetite (Fe3O4) with a small particle size of 5-8 nm due to the effective microwave-Assisted reduction method under continuous flow conditions. These nanoparticles were further characterized by a variety of spectroscopic techniques including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM)
The Effect Of Graphene On Catalytic Performance Of Palladium Nanoparticles Decorated With Fe3O4, Co3O4, And Ni (OH)2: Potential Efficient Catalysts Used For Suzuki Cross—Coupling
Abstract: In this research, we report a scientific investigation of an efficient method used for the synthesis of highly active Palladium Nanoparticles decorated with Fe3O4, Co3O4, and Ni (OH)2 Supported on Graphene as Potential Efficient Catalysts for Suzuki Cross—Coupling. Pd/Fe3O4 nanoparticles supported on graphene nanosheets (Pd/Fe3O4/G) showed an excellent catalytic activity for Suzuki coupling reactions and recycled for up to four times without loss of catalytic activity. An efficient magnetic catalyst has been successfully synthesized using a simple, reproducible fast and reliable method using microwave irradiation conditions. The prepared catalysts are magnetic as in case of iron and cobalt oxides which is an advantage in the separation process of catalyst from the reaction medium via applying a strong external magnetic field. The synthesis approach is based on the Microwave (MW)-assisted simultaneous reduction of palladium and ferric nitrates in the presence of graphene oxide (GO) nanosheets using hydrazine hydrate as the reducing agent. The results provide a fundamental understanding of the system variables by comparing the catalytic activity and recyclability of different catalysts with different properties. The most active and recyclable catalyst was Pd–Fe3O4—supported on graphene which offers several added advantages including recyclability of up to seven times, mild reaction conditions, and short reaction times in an environmentally benign solvent system. Furthermore, the magnetic properties imparted by the Fe3O4 component of the catalyst enables the catalyst to be easily isolated and recycled, thus greatly simplifying the ability to purify the reaction products and increasing the economic value of the catalyst. The utility of these magnetic catalysts towards Suzuki cross coupling reaction was also demonstrated. The high activity and recyclability of these catalysts are attributed to a strong catalyst-support interaction where the defect sites in the reduced GO nanosheets act as nucleation centers for anchoring the Pd and Fe3O4 nanoparticles thus minimizing the potential of their agglomeration and the subsequent decrease in the catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]
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