The detection of a spleen focus-forming virus neoantigen by lymphocyte- mediated cytolysis

The existence of a nonvirion tumor-associated cell surface antigen (TASA) on cells transformed with Friend (FLV) on Rauscher (RLV) leukemia virus has been difficult to demonstrate. Antisera raised against classically defined Friend- Moloney-Rauscher antigenic determinants have been shown to react with virus structural proteins coded for by genetic information contained in the lymphatic leukemia or helper (LLV) virus genome. The recent development of nontrans-formed fibroblast cell lines which contain the replication-defective spleen focus-forming virus (SFFV) genome, free of replicating LLV, has allowed investigation of an SFFV-specific antigen. We have applied the techniques of mixed tumor-lymphocyte culture stimulation followed by lymphocyte-mediated cytolysis assays to search for the cell surface expression of an antigen coded expressly by SFFV genetic information. SFFV nonproducer-immune, in vitro activated spleen cells were capable of effecting the lysis of SFFV-containing BALB/c 3T3 and Fischer rat epithelial, cloned cell lines. Normal BALB/c 3T3 and BALB/c 3T3 cells infected with three types of ecotropic LLV were unaffected. Syngeneic FLV and RLV-induced murine leukemia cells were also killed by SFFV nonproducer-immune lymphocytes. In addition, Kirsten sarcoma virus-transformed, replication-defective and replication-rescued BALB/c 3T3 fibroblasts were not susceptible to SFFV antigen-directed cytolysis. Antibody-dependent complement-mediated cytolysis assays using monospecific goat antisera confirmed that SFFV nonproducers lacked cell surface expression of virion structural proteins. These observations suggest that the antigen detected in LMC experiments was not coded for by genetic information contained in the helper component of FLV, and that it represents a true SFFV-specific cell surface antigen. Based upon the recent molecular evaluation of the SFFV genome as consisting of both xenotropic and ecotropic virus sequences, it appears reasonable that xenotropic genetic information may be responsible for expression of the SFFV- specific antigen. Since the replication-defective SFFV genome is also responsible for the malignant transformation associated with FLV-induced erythroleukemia, one might postulate that gene sequences capable of programming transformation may also code for the TASA detected in these studies

Low energy photoelectron diffraction analysis at high angular resolution of Cu and Mn/Cu surfaces

X-ray photoelectron diffraction simulations using a real-space approach are Shown to accurately produce the extraordinarily detailed photoelectron diffraction pattern from Cu{111} at an electron kinetic energy of 523.5 eV. These same simulations show that most sensitivity is obtained when using low energy electrons at high angular resolution Structural differences are observed to be greatest around a kinetic energy of similar to 100 eV and many of the features observed in the photoelectron diffraction patterns may be directly related to phenomena observed in low energy electron diffraction patterns from the same Surface. For Cu{100}. simulations of buckled surfaces with a Mn overlayer predict that low energy photoelectron diffraction can easily discriminate chemical and structural differences. Even the effects of the relaxed Surface of Cu{100} is indeed observable along azimuthal scans around a kinetic energy of 100 eV Our results show that low energy photoelectron diffraction is extremely sensitive to changes in Surface Structure If high resolution patterns are acquired. © 2009, American Institute of Physics

Comparison of 20nm silver nanoparticles synthesized with and without a gold core: Structure, dissolution in cell culture media, and biological impact on macrophages

Widespread use of silver nanoparticles raises questions of environmental and biological impact. Many synthesis approaches are used to produce pure silver and silver-shell gold-core particles optimized for specific applications. Since both nanoparticles and silver dissolved from the particles may impact the biological response, it is important to understand the physicochemical characteristics along with the biological impact of nanoparticles produced by different processes. The authors have examined the structure, dissolution, and impact of particle exposure to macrophage cells of two 20 nm silver particles synthesized in different ways, which have different internal structures. The structures were examined by electron microscopy and dissolution measured in Rosewell Park Memorial Institute media with 10% fetal bovine serum. Cytotoxicity and oxidative stress were used to measure biological impact on RAW 264.7 macrophage cells. The particles were polycrystalline, but 20 nm particles grown on gold seed particles had smaller crystallite size with many high-energy grain boundaries and defects, and an apparent higher solubility than 20 nm pure silver particles. Greater oxidative stress and cytotoxicity were observed for 20 nm particles containing the Au core than for 20 nm pure silver particles. A simple dissolution model described the time variation of particle size and dissolved silver for particle loadings larger than 9 μg/ml for the 24-h period characteristic of many in-vitro studies

The Dynamic Chain Event Graph

In this paper we develop a formal dynamic version of Chain Event Graphs (CEGs), a particularly expressive family of discrete graph- ical models. We demonstrate how this class links to semi-Markov models and provides a convenient generalization of the Dynamic Bayesian Network (DBN). In particular we develop a repeating time-slice Dynamic CEG providing a useful and simpler model in this family. We demonstrate how the Dynamic CEG’s graphical formulation exhibits asymmetric conditional independence statements and also how each model can be estimated in a closed form enabling fast model search over the class. The expressive power of this model class together with its estimation is illustrated throughout by a variety of examples that include the risk of childhood hospitalization and the efficacy of a flu vaccine

The Management and Use of Social Network Sites in a Government Department

In this paper we report findings from a study of social network site use in a UK Government department. We have investigated this from a managerial, organisational perspective. We found at the study site that there are already several social network technologies in use, and that these: misalign with and problematize organisational boundaries; blur boundaries between working and social lives; present differing opportunities for control; have different visibilities; have overlapping functionality with each other and with other information technologies; that they evolve and change over time; and that their uptake is conditioned by existing infrastructure and availability. We find the organisational complexity that social technologies are often hoped to cut across is, in reality, something that shapes their uptake and use. We argue the idea of a single, central social network site for supporting cooperative work within an organisation will hit the same problems as any effort of centralisation in organisations. We argue that while there is still plenty of scope for design and innovation in this area, an important challenge now is in supporting organisations in managing what can best be referred to as a social network site 'ecosystem'.Comment: Accepted for publication in JCSCW (The Journal of Computer Supported Cooperative Work

International Society of Sports Nutrition position stand: beta-alanine

Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of beta-alanine supplementation. Based on the current available literature, the conclusions of the ISSN are as follows: 1) Four weeks of beta-alanine supplementation (4–6 g daily) significantly augments muscle carnosine concentrations, thereby acting as an intracellular pH buffer; 2) Beta-alanine supplementation currently appears to be safe in healthy populations at recommended doses; 3) The only reported side effect is paraesthesia (tingling), but studies indicate this can be attenuated by using divided lower doses (1.6 g) or using a sustained-release formula; 4) Daily supplementation with 4 to 6 g of beta-alanine for at least 2 to 4 weeks has been shown to improve exercise performance, with more pronounced effects in open end-point tasks/time trials lasting 1 to 4 min in duration; 5) Beta-alanine attenuates neuromuscular fatigue, particularly in older subjects, and preliminary evidence indicates that beta-alanine may improve tactical performance; 6) Combining beta-alanine with other single or multi-ingredient supplements may be advantageous when supplementation of beta-alanine is high enough (4–6 g daily) and long enough (minimum 4 weeks); 7) More research is needed to determine the effects of beta-alanine on strength, endurance performance beyond 25 min in duration, and other health-related benefits associated with carnosine