Polyamine regulation of nitric oxide production in LPS-activated macrophages

© European Communities, 1999 Reproduction is authorised provided the source is acknowledgedPolyamines are physiological cellular constituents essential for cell growth and differentiation, and regulate a multitude of cellular functions (1-4). Nitric oxide (NO) is an effector molecule in both the cardiovascular and nervous systems (5,6). Intracellularly, NO and polyamines are derived from arginine, the latter via the rate-limiting enzyme ornithine decarboxylase (ODC; 7). This enzyme, like the inducible nitric oxide synthase (iNOS), is induced by proinflammatory cytokines and bacterial lipopolysaccharide (LPS), resulting in enhanced enzyme activity and increased polyamine biosynthesis (8,9). While the increase in polyamine synthesis would have important implications for cell growth and proliferation, it is not clear how this might affect iNOS pathway. Inhibition of polyamine biosynthesis impairs the phagocytic capacity of macrophages (10) and can block macrophage activation by tumour necrosis factor (11). Recently, exogenous polyamines have been shown to inhibit NO production in LPS-activated J774 cells (12) and by isolated neuronal NO synthase (13). However, these effects required relatively high concentrations of polyamines compared to those found in plasma and in intact cells (14), and appear to be due to aldehyde metabolites resulting from polyamine oxidation by the amine oxidase present in calf serum (15-17). In this study we have explored the effects of both endogenous and exogenous polyamines on the inducible L-arginine-NO pathway by examining whether inhibition of ornithine decarboxylase (ODC) and thus of polyamine biosynthesis (7), regulates NO production in lipopolysaccharide-activated J774 cells, a murine macrophage cell lineFinal Published versio

Concepts for the design of an antimatter annihilation rocket

Matter-antimatter annihilation is considered for spacecraft propulsion. Annihilation produces considerably more energy per unit mass of propellant than any other known means of energy production. An antimatter annihilation rocket requires several systems and components that are unique to its nature. Among these are an antimatter storage system, a means to extract the antimatter from storage, a system to transport the antimatter to the rocket engine, and the engine wherein annihilation occurs and thrust is produced. Design concepts of these systems and components are presented and discussed

Investigation of matter-antimatter interaction for possible propulsion applications

Matter-antimatter annihilation is discussed as a means of rocket propulsion. The feasibility of different means of antimatter storage is shown to depend on how annihilation rates are affected by various circumstances. The annihilation processes are described, with emphasis on important features of atom-antiatom interatomic potential energies. A model is developed that allows approximate calculation of upper and lower bounds to the interatomic potential energy for any atom-antiatom pair. Formulae for the upper and lower bounds for atom-antiatom annihilation cross-sections are obtained and applied to the annihilation rates for each means of antimatter storage under consideration. Recommendations for further studies are presented

Elemental, isotopic, and geochronological variability in Mogollon-Datil volcanic province archaeological obsidian, southwestern USA: Solving issues of intersource discrimination

Solving issues of intersource discrimination in archaeological obsidian is a recurring problem in geoarchaeological investigation, particularly since the number of known sources of archaeological obsidian worldwide has grown nearly exponentially in the last few decades, and the complexity of archaeological questions asked has grown equally so. These two parallel aspects of archaeological investigation have required more exacting understanding of the geological relationship between sources and the more accurate analysis of these sources of archaeological obsidian. This is particularly the case in the North American Southwest where the frequency of archaeological investigation is some of the highest in the world, and the theory and method used to interpret that record has become increasingly nuanced. Here, we attempt to unravel the elemental similarity of archaeological obsidian in the Mogollon-Datil volcanic province of southwestern New Mexico where some of the most important and extensively distributed sources are located and the elemental similarity between the sources is great even though the distance between the sources is large. Uniting elemental, isotopic, and geochronological analyses as an intensive pilot study, we unpack this complexity to provide greater understanding of these important sources of archaeological obsidian

Thermal contraints on high-pressure granulite metamorphism of supracrustal rocks

The circumstances leading to the formation and exposure at the Earth's surface of supracrustal granulites are examined. These are defined as sediments, volcanics, and other rock units which originally formed at the surface of the Earth, were metamorphosed to high-pressure granulite facies (T = 700-900 C, P = 5-10 kbar), and reexposed at the Earth's surface, in many cases underlain by normal thicknesses of continental crust (30-40 km). Five possible heating mechanisms to account for granulite metamorphism of supracrustal rocks are discussed: magnetic heating, thermal relaxation of perturbed temperature profiles following underthrusting of the continental crust, thermal relaxation after underthrusting of thin slivers of supracrustal rocks below continental crust of normal thickness, major preheating of the upper plate, and shear heating caused by frictional stress along the thrust plane

Cosmic antimatter annihilation and the gamma-ray background spectrum

Cosmic antimatter annihilation and gamma ray background spectru

Diving Demand for Large Ship Artificial Reefs

Using data drawn from a web-based travel cost survey, we jointly model revealed and stated preference trip count data in an attempt to estimate the recreational use value from diving the intentionally sunk USS Oriskany. Respondents were asked to report their: (i) actual trips from the previous year, (ii) anticipated trips in the next year, and (iii) anticipated trips next year assuming a second diveable vessel (a Spruance class destroyer) is sunk in the same vicinity. Results from several different model specifications indicate average per-person, per-trip use values range from $480 to$750. The “bundling†of a second vessel in the area of the Oriskany to create a multiple-ship artificial reef area adds between $220 and$1,160 per diver per year in value.Artificial reefs, diving, recreation demand, combined revealed and stated preferences, non-market valuation, Institutional and Behavioral Economics, Marketing, Productivity Analysis, Public Economics, Research Methods/ Statistical Methods, Q26, Q50,

Unpowered Aerodynamic Characteristics of a 15-Percent Scale Model of a Twin-Engine Commuter Aircraft

An experimental investigation was conducted in the Ames 12-Foot Pressure Wind Tunnel to determine the unpowered aerodynamic characteristics of a 15-percent-scale model of a twin-engine commuter aircraft. Model longitudinal aerodynamic characteristics were examined at discrete flap deflections for various angle-of-attack and wind-tunnel-velocity ranges with the empennage on and off. Data are presented for the basic model configuration consisting of the fuselage, wing, basic wing leading edge, double slotted flaps, midengine nacelles, and empennage. Other configurations tested include a particle-span drooped leading edge (dropped outboard of the engine nacelles), a full-span drooped leading edge, low- and high-mounted engine nacelles, and a single-slotted flap. An evaluation was made of the model mounting system by comparing data obtained with the model mounted conventionally on the wind-tunnel model-support struts and the model inverted