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Methicillin-resistant Staphylococcus aureus (MRSA) strains from different geographic areas have different genetic backgrounds, suggesting independent clonal evolutions. To better understand the virulence of MRSA strains and the relationship to their clonal and geographic origins, we undertook an analysis of epidemiologic, molecular, and virulence characteristics of a large number of MRSA isolates from geographically diverse origins, in a Caenorhabditis elegans infection model. A total of 99 MRSA isolates collected between 1993 and 2010 at the Geneva University Hospitals from diverse global origins were characterized with Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin (TSST), accessory gene regulator ( agr) group, staphylococcal cassette chromosome mec (SCC mec), S. aureus protein A ( spa), multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE) typing. Epidemiologic data were provided from clinical records. The bacterial virulence was tested in a C. elegans host model. The inter-relationships of epidemiological/molecular characteristics in association with nematocidal activities were analyzed with univariate and two-factor analysis of variance (ANOVA). Community-associated MRSA (CA-MRSA) strains were more virulent than hospital-associated MRSA (HA-MRSA), with higher nematocidal activities in CA-MRSA strains (0.776 vs. 0.506, p = 0.0005). All molecular characteristics (PVL, TSST, spa, SCC mec, MLST, and PFGE types) showed a significant association with nematocidal activities on univariate analysis ( p < 0.005). PVL was not a significant predictor after adjusting for genomic backgrounds using spa, MLST, or PFGE typing. The dominant CA-MRSA strains in North America showed higher nematocidal activities than strains from other regions ( p < 0.0001). Strains with global origins containing distinct genetic backgrounds have different virulence in the C. elegans model. Nematocidal activities were most highly correlated with SCC mec, spa, MLST, and PFGE typing, suggesting that genomic background rather than a single exotoxin characteristic was the most discriminating predictor of virulence. [ABSTRACT FROM AUTHOR]

The International Space Station will require a continuous supply of replacement parts for ongoing maintenance and repair after the planned retirement of the space shuttle in 2010. These parts are existing line-replaceable items collectively called orbital replacement units, and include heavy and oversized items such as control moment gyroscopes and stowed radiator arrays originally intended for delivery aboard the space shuttle. Current resupply spacecraft have limited to no capability to deliver these external logistics. In support of NASA's Exploration Systems Architecture Study, a team at Langley Research Center designed an unpressurized cargo delivery vehicle to deliver bulk cargo to the space station. This vehicle was required to deliver at least 13,200 lb of cargo mounted on at least 18 flight releasable attachment mechanisms. The crew launch vehicle design recommended in the Exploration Systems Architecture Study would be used to launch one annual resupply flight to the International Space Station. The baseline vehicle design has a cargo capacity of 16,000 lb mounted on up to 20 flight releasable attachment mechanisms. Major vehicle components are an 18.0 ft-diam cargo module containing two detachable pallets with the payload, a service module to provide propulsion and power, and a jettisonable nose cone. To reduce cost and risk, the service module is identical to the one used for the crew exploration vehicle design. [ABSTRACT FROM AUTHOR]

Discusses research into the changing geomorphology of the San Francisco Bay Area in California, to a polycentric metropolitan form. Impact of polycentric development; Investigation into the effects of housing availability and prices; Empirical analysis of the situation.

Metals are widely distributed pollutants in water and can have detrimental effects on some aquatic life and humans. Over the past few decades, the United States Environmental Protection Agency (U.S. EPA) has published a series of criteria guidelines, which contain specific criteria maximum concentrations (CMCs) for 10 metals. However, CMCs for other metals are still lacking because of financial, practical, or ethical restrictions on toxicity testing. Herein, a quantitative structure activity relationship (QSAR) method was used to develop a set of predictive relationships, based on physical and chemical characteristics of metals, and predict acute toxicities of each species for five phyla and eight families of organisms for 25 metals or metalloids. In addition, species sensitivity distributions (SSDs) were developed as independent methods for determining predictive CMCs. The quantitative ion character–activity relationships (QICAR) analysis showed that the softness index (σp), maximum complex stability constants (log −βn), electrochemical potential (ΔE0), and covalent index (Xm2r) were the minimum set of structure parameters required to predict toxicity of metals to eight families of representative organisms. Predicted CMCs for 10 metals are in reasonable agreement with those recommended previously by U.S. EPA within a difference of 1.5 orders of magnitude. CMCs were significantly related to σp (r2 = 0.76, P = 7.02 × 10–9) and log −βn (r2 = 0.73, P = 3.88 × 10–8). The novel QICAR-SSD model reported here is a rapid, cost-effective, and reasonably accurate method, which can provide a beneficial supplement to existing methodologies for developing preliminarily screen level toxicities or criteria for metals, for which little or no relevant information on the toxicity to particular classes of aquatic organisms exists [ABSTRACT FROM AUTHOR]