Toxoplasma gondii major surface antigen (SAG1): in vitro analysis of host cell binding

Previous studies have indicated that SAG1, the major surface molecule of the protozoan parasite Toxoplasma gondii, is an important attachment ligand for the host cell. However, the research data that supports this claim comes largely from studies investigating tachyzoite binding, and not SAG1 binding per se. In this study we successfully developed an in vitro attachment assay to directly evaluate the mechanism of SAG1-host cell binding. Competition experiments were then performed using SAG1 that had been pre-treated with the neoglycoprotein BSA-glucosamide or with antibody. Soluble BSA-glucosamide blocked SAG1 attachment to MDBK cells in a dose-dependent manner, implying that SAG1 binding is mediated, in part, via attachment to host cell surface glucosamine. Interestingly, pre-incubation of SAG1 in polyclonal sera from chronically infected mice failed to block binding. This challenges the assumption that anti-SAG1 antibodies block parasite attachment through the masking of SAG1 host cell binding domains. Taken together, this evidence presents new strategies for understanding SAG1-mediated attachment

Phase diagram for a mixture of colloids and polymers with equal size

We present the phase diagram of a colloid-polymer mixture in which the radius a of the colloidal spheres is approximately the same as the radius R of a polymer coil (q=R/a1). A three-phase coexistence region is experimentally observed, previously only reported for colloid-polymer mixtures with smaller polymer chains (q0.6). A recently developed generalized free-volume theory (GFVT) for mixtures of hard spheres and non-adsorbing excluded-volume polymer chains gives a quantitative description of the phase diagram. Monte Carlo simulations also agree well with experimen

Asymptotic Giant Branch Variables in the Galaxy and the Local Group

AGB variables, particularly the large amplitude Mira type, are a vital step on the distance scale ladder. They will prove particularly important in the era of space telescopes and extremely large ground-based telescopes with adaptive optics, which will be optimized for infrared observing. Our current understanding of the distances to these stars is reviewed with particular emphasis on improvements that came from Hipparcos as well as on recent work on Local Group galaxies. In addition to providing the essential calibration for extragalactic distances Gaia may also provide unprecedented insight into the poorly understood mass-loss process itself.Comment: Accepted for publication in Astrophysics and Space Science. From a presentation at the conference "The Fundamental Cosmic Distance Scale: State of the Art and Gaia Perspective, Naples May 2011. 8 Pages, 9 Figure

Turbulence transport throughout the heliosphere

We employ a turbulence transport model to compute distributions of turbulence throughout the heliosphere. The model determines the radial dependence of three (coupled) quantities that characterize interplanetary turbulence, the energy per unit mass, the cross helicity or Alfvénicity, and a similarity length scale. A fourth integrated quantity, the plasma temperature, is modified by heat deposition due to turbulent dissipation. The model includes advection, expansion, and reflection effects as well as the tendency toward dynamic alignment, and a von Kármán type dissipation function that represents decay of turbulence due to cascade to small scales. Two types of forcing are also featured, one a simple model of stream shear, and the other a driving in the outer heliosphere associated with wave energy injection due to pickup protons of interstellar origin. Parameters for the model have been tuned using observation data from Voyager and Ulysses. We analyze the constraining observations to provide boundary conditions and parameters that vary with heliocentric latitude, with some extrapolations. The fully assembled model permits the computation of the distribution of turbulence throughout the entire heliosphere, and we present solutions for several appropriate parameter sets

The Impact of Link Suggestions on User Navigation and User Perception

The study reported in this paper explores the effects of providing web users with link suggestions that are relevant to their tasks. Results indicate that link suggestions were positively received. Furthermore, users perceived sites with link suggestions as more usable and themselves as less disoriented. The average task execution time was significantly lower than in the control condition and users appeared to navigate in a more structured manner. Unexpectedly, men took more advantage from link suggestions than women

HWVP NCAW melter feed rheology FY 1993 testing and analyses: Letter report

The Hanford Waste Vitrification Plant (HWVP) program has been established to immobilize selected Hanford nuclear wastes before shipment to a geologic repository. The HWVP program is directed by the U.S. Department of Energy (DOE). The Pacific Northwest Laboratory (PNL) provides waste processing and vitrification technology to assist the design effort. The focus of this letter report is melter feed rheology, Process/Product Development, which is part of the Task in the PNL HWVP Technology Development (PHTD) Project. Specifically, the melter feed must be transported to the liquid fed ceramic melter (LFCM) to ensure HWVP operability and the manufacture of an immobilized waste form. The objective of the PHTD Project slurry flow technology development is to understand and correlate dilute and concentrated waste, formatted waste, waste with recycle addition, and melter feed transport properties. The objectives of the work described in this document were to examine frit effects and several processing conditions on melter feed rheology. The investigated conditions included boiling time, pH, noble metal containing melter feed, solids loading, and aging time. The results of these experiments contribute to the understanding of melter feed rheology. This document is organized in eight sections. This section provides the introductory remarks, followed by Section 2.0 that contains conclusions and recommendations. Section 3.0 reviews the scientific principles, and Section 4.0 details the experimental methods. The results and discussion and the review of related rheology data are in Sections 5.0 and 6.0, respectively. Section 7.0, an analysis of NCAW melter feed rheology data, provides an overall review of melter feed with FY 91 frit. References are included in Section 8.0. This letter report satisfies contractor milestone PHTD C93-03.02E, as described in the FY 1993 Pacific Northwest Hanford Laboratory Waste Plant Technology Development (PHTD) Project Work Plan

Dynamic response of full-scale sandwich composite structures subject to air-blast loading

Glass-fibre reinforced polymer (GFRP) sandwich structures (1.6 m × 1.3 m) were subject to 30 kg charges of C4 explosive at stand-off distances 8–14 m. Experiments provide detailed data for sandwich panel response, which are often used in civil and military structures, where air-blast loading represents a serious threat. High-speed photography, with digital image correlation (DIC), was employed to monitor the deformation of these structures during the blasts. Failure mechanisms were revealed in the DIC data, confirmed in post-test sectioning. The experimental data provides for the development of analytical and computational models. Moreover, it underlines the importance of support boundary conditions with regards to blast mitigation. These findings were analysed further in finite element simulations, where boundary stiffness was, as expected, shown to strongly influence the panel deformation. In-depth parametric studies are ongoing to establish the hierarchy of the various factors that influence the blast response of sandwich composite structures

Dissociative paraplegia after epidural anesthesia: A case report

10.1186/1752-1947-7-56Journal of Medical Case Reports7