Membrane fusion mediated by baculovirus gp64 involves assembly of stable gp64 trimers into multiprotein aggregates

The baculovirus fusogenic activity depends on the low pH conformation of virally-encoded trimeric glycoprotein, gp64. We used two experimental approaches to investigate whether monomers, trimers, and/or higher order oligomers are functionally involved in gp64 fusion machine. First, dithiothreitol (DTT)- based reduction of intersubunit disulfides was found to reversibly inhibit fusion, as assayed by fluorescent probe redistribution between gp64-expressing and target cells (i.e., erythrocytes or Sf9 cells). This inhibition correlates with disappearance of gp64 trimers and appearance of dimers and monomers in SDS-PAGE. Thus, stable (i.e., with intact intersubunit disulfides) gp64 trimers, rather than independent monomers, drive fusion. Second, we established that merger of membranes is preceded by formation of large (greater than 2 MDa), short-lived gp64 complexes. These complexes were stabilized by cell-surface cross-linking and characterized by glycerol density gradient ultracentrifugation. The basic structural unit of the complexes is stable gp64 trimer. Although DTT-destabilized trimers were still capable of assuming the low pH conformation, they failed to form multimeric complexes. The fact that formation of these complexes correlated with fusion in timing, and was dependent on (a) low pH application, (b) stable gp64 trimers, and (c) cell-cell contacts, suggests that such multimeric complexes represent a fusion machine.     

The glycoprotein character of multiple forms of Aspergillus polygalacturonase

An epidemiological survey to characterize Entamoeba histolytica/E dispar isolates from 123 human subjects was carried out in the Wonji area of Central Ethiopia, where an increased incidence of amoebic infection has been reported. In a randomized, coproparasitological study, 93 (75.6%) of the subjects were found positive for at least one species of intestinal parasite: 14 (15.1%) harboured only one species and 79 (84.9%) were infected with at least two species. In-vitro culture in Robinson's medium revealed amoebic parasites in 52 (82.5%) of the 63 cases tested. Of the 29 amoebic isolates successfully stabilized, cloned and characterized by Sargeaunt's electrophoretic technique, 27 (93.1%) were of E. dispar zymodemes (19 of zymodeme I, two each of zymodemes III, V and XI, and one each of zymodemes X and XV) and two (6.9%) were of E. histolytica (zymodeme XIII).     

Numerical and experimental LDL transport through arterial wall

Atherosclerosis develops from oxidized low-density lipoprotein molecules (LDL). When oxidized LDL evolves in plaque formations within an artery wall, a series of reactions occur to repair the damage to the artery wall caused by oxidized LDL. Aim of this study was to compare experimental data of LDL transport through isolated blood vessel with computational results of bounding of oxidized LDL receptor-1 (LOX-1) for endothelial cells with numerical discrete methods such as dissipative particle dynamics (DPD) and lattice Boltzmann (LB) method. Experiments of LDL transport were performed on the isolated rabbit common carotid arteries acquired from fifteen rabbits after 12 weeks of high-fat diet. Oxidative LDL molecule is built and used for docking with LOX-1 receptor. Energies that give the best binding are computed, and the energy with greatest probability of attachment for oxidative LDL molecule and glutamine acid is further used in numerical simulations. Simulations using DPD and LB method use the computed binding energy to calculate the force necessary for binding of LDL molecule to the endothelial blood vessel layer. Experimental results have shown large uptake for shear stress below 1 dyn/cm². Computational results for both discrete methods DPD and LB have shown good accuracy with experimental data. Calculation of the interactive molecule forces from computational chemistry open a new avenue for multiscale modeling methods, which will give better insight for the understanding and the prediction of LDL transport through the arterial wall for the medical community.     

Symmetrical components estimation through nonrecursive Newton-type numerical algorithm

The paper reports new software developments for symmetrical components estimation. Nonrecursive Newton-type algorithm is extended with the second stage algorithm for symmetrical components calculation from the estimated fundamental phasors of three-phase signals (arbitrary voltages or currents). The algorithm is not sensitive to power system frequency changes and to the harmonic distortion of input signals. The algorithm is tested through computer simulations and by using laboratory obtained input signals and those recorded in the real distribution network.     

Effect of the sample sizes and the sampling conditions on the results of chemical analysis of castings of Cu−Sn and Cu−Sn−Pb alloys

In horizontal continuous casting of semifinished products made of alloys of the Cu−Sn and Cu−Sn−Pb systems segregation of tin and lead complicates the problem of obtaining the specified composition. The aim of this work consists in determining the size of the sample and the conditions for taking it in casting for which the specified chemical composition of the casting will be uniform over the entire volume. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 34–35, October, 1998.     

Preparation and Comprehensive Characterization of a Calcium Hydroxyapatite Reference Material

Numerous biological and chemical studies involve the use of calcium hydroxyapatite (HA), Ca₁₀(PO₄)₆(OH)₂. In this study detailed physicochemical characterization of HA, prepared from an aqueous solution, was carried out employing different methods and techniques: chemical and thermal analyses, x-ray diffraction, infrared and Raman spectroscopies, scanning and transmission microscopies, and Brunauer, Emmett, and Teller (BET) surface-area method. The contents of calcium (Ca²⁺), phosphate (PO₄³⁻), hydroxide (OH⁻), hydrogenphosphate (HPO₄²⁻), water (H₂O), carbonate (CO₃²⁻), and trace constituents, the Ca/P molar ratio, crystal size and morphology, surface area, unit-cell parameters, crystallinity, and solubility of this HA were determined. This highly pure, homogeneous, and highly crystalline HA is certified as a National Institute of Standards and Technology (NIST) standard reference material, SRM 2910.     

THE Drive-Wave Shape Influence on the Class C Tuned HF High-Power Amplifiers

The paper investigates the drive-wave shape influence on the performances of tuned HF high-power amplifiers. Using the linear model of high-power HF triode and changing the drive wave shape (cosine, triangular, trapezoidal and pulse) under the same conditions (conducting angle, drive level), the balance of power for the high efficiency design, representing the normalized maximum output power and the efficiency versus the conducting angle or other parameter, are compared.     

Experimental combination of intensity and stereo edges for improved snake segmentation

In this paper, we present an algorithm to combine edge information from stereo-derived disparity maps with edges from the original intensity/color image to improve the contour detection in images of natural scenes. After computing the disparity map, we generate a so-called “edge-combination image,” which relies on those edges of the original image that are also present in the stereo map. We describe an algorithm to identify corresponding intensity and disparity edges, which are usually not perfectly aligned due to errors in the stereo reconstruction. Our experiments show that the proposed edge-combination approach can significantly improve the segmentation results of an active contour algorithm. The text was submitted by the authors in English. Danijela Markovic graduated from the Faculty of Electronic Engineering, University of Nis, Serbia in 1997. She is currently a PhD student at the Institute for Software Technology and Interactive Systems, Vienna University of Technology. Her research interests are in computer vision and computer graphics, including stereo vision and curve/surface modeling. Particularly, she is interested in object segmentation, feature extraction, and tracking. Margrit Gelautz received her PhD degree in computer science from Graz University of Technology, Austria. She worked on stereo and interferometric image processing for radar remote sensing applications during a postdoctoral stay at Stanford University. Her current research interests include image and video processing for multimedia applications, with a focus on 3D vision and rendering techniques.