Receptor-mediated endocytosis and intracellular trafficking of insulin and low-density lipoprotein by retinal vascular endothelial cells

PURPOSE: The authors investigated the receptor-mediated endocytosis (RME) and intracellular trafficking of insulin and low-density lipoprotein (LDL) in cultured retinal vascular endothelial cells (RVECs). METHODS: Low-density lipoprotein and insulin were conjugated to 10 nm colloidal gold, and these ligands were added to cultured bovine RVECs for 20 minutes at 4 degrees C. The cultures were then warmed to 37 degrees C and fixed after incubation times between 30 seconds and 1 hour. Control cells were incubated with unconjugated gold colloid at times and concentrations similar to those of the ligands. Additional control cells were exposed to several concentrations of anti-insulin receptor antibody or a saturating solution of unconjugated insulin before incubation with gold insulin. RESULTS: Using transmission electron microscopy, insulin gold and LDL gold were both observed at various stages of RME. Insulin-gold particles were first seen to bind to the apical plasma membrane (PM) before clustering in clathrin-coated pits and internalization in coated vesicles. Gold was later visualized in uncoated cytoplasmic vesicles, corresponding to early endosomes and multivesicular bodies (MVBs) or late endosomes. In several instances, localized regions of the limiting membrane of the MVBs appeared coated, a feature of endosomal membranes not previously described. After RME at the apical PM and passage through the endosomal system, the greater part of both insulin- and LDL-gold conjugates was seen to accumulate in large lysosome-like compartments. However, a small but significant proportion of the internalized ligands was transcytosed and released as discrete membrane-associated quanta at the basal cell surface. The uptake of LDL gold was greatly increased in highly vacuolated, late-passage RVECs. In controls, anti-insulin receptor antibody and excess unconjugated insulin caused up to 89% inhibition in gold-insulin binding and internalization. CONCLUSION: These results illustrate the internalization and intracellular trafficking by RVECs of insulin and LDL through highly efficient RME, and they provide evidence for at least two possible fates for the endocytosed ligands. This study outlines a route by which vital macromolecules may cross the inner blood-retinal barrier.

Exclusion of linkage between schizophrenia and the D2 dopamine receptor gene region of chromosome 11q in 112 Irish multiplex families

A leading theory hypothesizes that schizophrenia arises from dysregulation of the dopamine system in certain brain regions. As this dysregulation could arise from abnormal expression of D2 dopamine receptors, the D2 receptor gene (DRD2) on chromosome 11q is a candidate locus for schizophrenia. We tested whether allelic variation at DRD2 and five surrounding loci cosegregated with schizophrenia in 112 small- to moderate-size Irish families containing two or more members affected with schizophrenia or schizoaffective disorder, defined by DSM-III-R. Evidence of linkage was assessed using varying definitions of illness and modes of transmission. Assuming genetic homogeneity, linkage between schizophrenia and large regions of 11q around DRD2 could be strongly excluded. Assuming genetic heterogeneity, variation at the DRD2 locus could be rejected as a major risk factor for schizophrenia in more than 50% of these families for all models tested and in as few as 25% of the families for certain models. The DRD2 linkage in fewer than 25% of these families could not be excluded under any of the models tested. Our results suggest that the major component of genetic susceptibility to schizophrenia is not due to allelic variation at the DRD2 locus or other genes in the surrounding chromosomal region.

Mechanisms and sources of passive intermodulation in printed circuits

Modern wireless systems are expected to operate in multiple frequency bands and support diverse communications standards to provide the high volume and speed of data transmission. Today's major limitations of their performance are imposed by interference, spurious emission and noise generated by high-power carriers in antennas and passive components of the RF front-end. Passive Intermodulation (PIM), which causes the combinatorial frequency generation in the operational bands, presents a primary challenge to signal integrity, system efficacy and data throughput. © 2013 IEEE.

Physical and dynamical characterisation of low ΔV NEA (190491) 2000 FJ10

Aims: We investigated the physical properties and dynamical evolution of near-Earth asteroid (NEA) (190491) 2000 FJ10 in order to assess the suitability of this accessible NEA as a space mission target. Methods: Photometry and colour determination were carried out with the 1.54 m Kuiper Telescope (Mt Bigelow, USA) and the 10 m Southern African Large Telescope (SALT; Sutherland, South Africa) during the object's recent favourable apparition in 2011-12. During the earlier 2008 apparition, a spectrum of the object in the 6000-9000 Angstrom region was obtained with the 4.2 m William Herschel Telescope (WHT; Canary Islands, Spain). Interpretation of the observational results was aided by numerical simulations of 1000 dynamical clones of 2000 FJ10 up to 106 yr in the past and in the future. Results: The asteroid's spectrum and colours determined by our observations suggest a taxonomic classification within the S-complex although other classifications (V, D, E, M, P) cannot be ruled out. On this evidence, it is unlikely to be a primitive, relatively unaltered remnant from the early history of the solar system and thus a low priority target for robotic sample return. Our photometry placed a lower bound of 2 h to the asteroid's rotation period. Its absolute magnitude was estimated to be 21.54 ± 0.1 which, for a typical S-complex albedo, translates into a diameter of 130 ± 20 m. Our dynamical simulations show that it has likely been an Amor for the past 105 yr. Although currently not Earth-crossing, it will likely become so during the period 50-100 kyr in the future. It may have arrived from the inner or central main belt >1 Myr ago as a former member of a low-inclination S-class asteroid family. Its relatively slow rotation and large size make it a suitable destination for a human mission. We show that ballistic Earth-190491-Earth transfer trajectories with ΔV <2 km s-1 at the asteroid exist between 2052 and 2061. Based on observations made with the Southern African Large Telescope (SALT).

Online Thévenin Equivalent Determination Considering System Side Changes and Measurement Errors

This paper presents a new method for online determination of the Thèvenin equivalent parameters of a power system at a given node using the local PMU measurements at that node. The method takes into account the measurement errors and the changes in the system side. An analysis of the effects of changes in system side is carried out on a simple two-bus system to gain an insight of the effect of system side changes on the estimated Thévenin equivalent parameters. The proposed method uses voltage and current magnitudes as well as active and reactive powers; thus avoiding the effect of phase angle drift of the PMU and the need to synchronize measurements at different instances to the same reference. Applying the method to the IEEE 30-bus test system has shown its ability to correctly determine the Thévenin equivalent even in the presence of measurement errors and/or system side changes.

Psychosocial aspects in cardiac rehabilitation: From theory to practice. A position paper from the Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation of the European Society of Cardiology

A large body of empirical research shows that psychosocial risk factors (PSRFs) such as low socio-economic status, social isolation, stress, type-D personality, depression and anxiety increase the risk of incident coronary heart disease (CHD) and also contribute to poorer health-related quality of life (HRQoL) and prognosis in patients with established CHD. PSRFs may also act as barriers to lifestyle changes and treatment adherence and may moderate the effects of cardiac rehabilitation (CR). Furthermore, there appears to be a bidirectional interaction between PSRFs and the cardiovascular system. Stress, anxiety and depression affect the cardiovascular system through immune, neuroendocrine and behavioural pathways. In turn, CHD and its associated treatments may lead to distress in patients, including anxiety and depression. In clinical practice, PSRFs can be assessed with single-item screening questions, standardised questionnaires, or structured clinical interviews. Psychotherapy and medication can be considered to alleviate any PSRF-related symptoms and to enhance HRQoL, but the evidence for a definite beneficial effect on cardiac endpoints is inconclusive. A multimodal behavioural intervention, integrating counselling for PSRFs and coping with illness should be included within comprehensive CR. Patients with clinically significant symptoms of distress should be referred for psychological counselling or psychologically focused interventions and/or psychopharmacological treatment. To conclude, the success of CR may critically depend on the interdependence of the body and mind and this interaction needs to be reflected through the assessment and management of PSRFs in line with robust scientific evidence, by trained staff, integrated within the core CR team.

Molecular pedigree reconstruction and estimation of evolutionary parameters in a wild Atlantic salmon river system with incomplete sampling: a power analysis

Background: Pedigree reconstruction using genetic analysis provides a useful means to estimate fundamental population biology parameters relating to population demography, trait heritability and individual fitness when combined with other sources of data. However, there remain limitations to pedigree reconstruction in wild populations, particularly in systems where parent-offspring relationships cannot be directly observed, there is incomplete sampling of individuals, or molecular parentage inference relies on low quality DNA from archived material. While much can still be inferred from incomplete or sparse pedigrees, it is crucial to evaluate the quality and power of available genetic information a priori to testing specific biological hypotheses. Here, we used microsatellite markers to reconstruct a multi-generation pedigree of wild Atlantic salmon (Salmo salar L.) using archived scale samples collected with a total trapping system within a river over a 10 year period. Using a simulation-based approach, we determined the optimal microsatellite marker number for accurate parentage assignment, and evaluated the power of the resulting partial pedigree to investigate important evolutionary and quantitative genetic characteristics of salmon in the system.

Results: We show that at least 20 microsatellites (ave. 12 alleles/locus) are required to maximise parentage assignment and to improve the power to estimate reproductive success and heritability in this study system. We also show that 1.5 fold differences can be detected between groups simulated to have differing reproductive success, and that it is possible to detect moderate heritability values for continuous traits (h(2) similar to 0.40) with more than 80% power when using 28 moderately to highly polymorphic markers.

Conclusion: The methodologies and work flow described provide a robust approach for evaluating archived samples for pedigree-based research, even where only a proportion of the total population is sampled. The results demonstrate the feasibility of pedigree-based studies to address challenging ecological and evolutionary questions in free-living populations, where genealogies can be traced only using molecular tools, and that significant increases in pedigree assignment power can be achieved by using higher numbers of markers.

The Fasciola hepatica genome: gene duplication and polymorphism reveals adaptation to the host environment and the capacity for rapid evolution

BACKGROUND: The liver fluke Fasciola hepatica is a major pathogen of livestock worldwide, causing huge economic losses to agriculture, as well as 2.4 million human infections annually.

RESULTS: Here we provide a draft genome for F. hepatica, which we find to be among the largest known pathogen genomes at 1.3 Gb. This size cannot be explained by genome duplication or expansion of a single repeat element, and remains a paradox given the burden it may impose on egg production necessary to transmit infection. Despite the potential for inbreeding by facultative self-fertilisation, substantial levels of polymorphism were found, which highlights the evolutionary potential for rapid adaptation to changes in host availability, climate change or to drug or vaccine interventions. Non-synonymous polymorphisms were elevated in genes shared with parasitic taxa, which may be particularly relevant for the ability of the parasite to adapt to a broad range of definitive mammalian and intermediate molluscan hosts. Large-scale transcriptional changes, particularly within expanded protease and tubulin families, were found as the parasite migrated from the gut, across the peritoneum and through the liver to mature in the bile ducts. We identify novel members of anti-oxidant and detoxification pathways and defined their differential expression through infection, which may explain the stage-specific efficacy of different anthelmintic drugs.

CONCLUSIONS: The genome analysis described here provides new insights into the evolution of this important pathogen, its adaptation to the host environment and external selection pressures. This analysis also provides a platform for research into novel drugs and vaccines.

An improved TLBO with elite strategy for parameters identification of PEM fuel cell and solar cell models

Clean and renewable energy generation and supply has drawn much attention worldwide in recent years, the proton exchange membrane (PEM) fuel cells and solar cells are among the most popular technologies. Accurately modeling the PEM fuel cells as well as solar cells is critical in their applications, and this involves the identification and optimization of model parameters. This is however challenging due to the highly nonlinear and complex nature of the models. In particular for PEM fuel cells, the model has to be optimized under different operation conditions, thus making the solution space extremely complex. In this paper, an improved and simplified teaching-learning based optimization algorithm (STLBO) is proposed to identify and optimize parameters for these two types of cell models. This is achieved by introducing an elite strategy to improve the quality of population and a local search is employed to further enhance the performance of the global best solution. To improve the diversity of the local search a chaotic map is also introduced. Compared with the basic TLBO, the structure of the proposed algorithm is much simplified and the searching ability is significantly enhanced. The performance of the proposed STLBO is firstly tested and verified on two low dimension decomposable problems and twelve large scale benchmark functions, then on the parameter identification of PEM fuel cell as well as solar cell models. Intensive experimental simulations show that the proposed STLBO exhibits excellent performance in terms of the accuracy and speed, in comparison with those reported in the literature.

Long-Term Economic Model for Allocation of FACTS Devices in Restructured Power System Integrated Wind Generation

This study proposes an approach to optimally allocate multiple types of flexible AC transmission system (FACTS) devices in market-based power systems with wind generation. The main objective is to maximise profit by minimising device investment cost, and the system's operating cost considering both normal conditions and possible contingencies. The proposed method accurately evaluates the long-term costs and benefits gained by FACTS devices (FDs) installation to solve a large-scale optimisation problem. The objective implies maximising social welfare as well as minimising compensations paid for generation re-scheduling and load shedding. Many technical operation constraints and uncertainties are included in problem formulation. The overall problem is solved using both particle swarm optimisations for attaining optimal FDs allocation as main problem and optimal power flow as sub-optimisation problem. The effectiveness of the proposed approach is demonstrated on modified IEEE 14-bus test system and IEEE 118-bus test system.

Elastodynamic Modeling and Analysis for an Exechon Parallel Kinematic Machine

As a newly invented parallel kinematic machine (PKM), Exechon has attracted intensive attention from both academic and industrial fields due to its conceptual high performance. Nevertheless, the dynamic behaviors of Exechon PKM have not been thoroughly investigated because of its structural and kinematic complexities. To identify the dynamic characteristics of Exechon PKM, an elastodynamic model is proposed with the substructure synthesis technique in this paper. The Exechon PKM is divided into a moving platform subsystem, a fixed base subsystem and three limb subsystems according to its structural features. Differential equations of motion for the limb subsystem are derived through finite element (FE) formulations by modeling the complex limb structure as a spatial beam with corresponding geometric cross sections. Meanwhile, revolute, universal, and spherical joints are simplified into virtual lumped springs associated with equivalent stiffnesses and mass at their geometric centers. Differential equations of motion for the moving platform are derived with Newton's second law after treating the platform as a rigid body due to its comparatively high rigidity. After introducing the deformation compatibility conditions between the platform and the limbs, governing differential equations of motion for Exechon PKM are derived. The solution to characteristic equations leads to natural frequencies and corresponding modal shapes of the PKM at any typical configuration. In order to predict the dynamic behaviors in a quick manner, an algorithm is proposed to numerically compute the distributions of natural frequencies throughout the workspace. Simulation results reveal that the lower natural frequencies are strongly position-dependent and distributed axial-symmetrically due to the structure symmetry of the limbs. At the last stage, a parametric analysis is carried out to identify the effects of structural, dimensional, and stiffness parameters on the system's dynamic characteristics with the purpose of providing useful information for optimal design and performance improvement of the Exechon PKM. The elastodynamic modeling methodology and dynamic analysis procedure can be well extended to other overconstrained PKMs with minor modifications.

M Dwarf Flare Continuum Variations on One-second Timescales: Calibrating and Modeling of ULTRACAM Flare Color Indices

We present a large data set of high-cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements provide constraints for models of the near-ultraviolet (NUV) and optical continuum spectral evolution on timescales of ≈1 s. We provide a robust interpretation of the flare emission in the ULTRACAM filters using simultaneously obtained low-resolution spectra during two moderate-sized flares in the dM4.5e star YZ CMi. By avoiding the spectral complexity within the broadband Johnson filters, the ULTRACAM filters are shown to characterize bona fide continuum emission in the NUV, blue, and red wavelength regimes. The NUV/blue flux ratio in flares is equivalent to a Balmer jump ratio, and the blue/red flux ratio provides an estimate for the color temperature of the optical continuum emission. We present a new “color-color” relationship for these continuum flux ratios at the peaks of the flares. Using the RADYN and RH codes, we interpret the ULTRACAM filter emission using the dominant emission processes from a radiative-hydrodynamic flare model with a high nonthermal electron beam flux, which explains a hot, T ≈ 104 K, color temperature at blue-to-red optical wavelengths and a small Balmer jump ratio as observed in moderate-sized and large flares alike. We also discuss the high time resolution, high signal-to-noise continuum color variations observed in YZ CMi during a giant flare, which increased the NUV flux from this star by over a factor of 100. Based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium, based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias, and observations, and based on observations made with the ESO Telescopes at the La Silla Paranal Observatory under programme ID 085.D-0501(A).