101 research outputs found

    Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of ascaris reveals a novel fold and two discrete lipid-binding sites

    Get PDF
    Parasitic nematode worms cause serious health problems in humans and other animals. They can induce allergic-type immune responses, which can be harmful but may at the same time protect against the infections. Allergens are proteins that trigger allergic reactions and these parasites produce a type that is confined to nematodes, the nematode polyprotein allergens (NPAs). These are synthesized as large precursor proteins comprising repeating units of similar amino acid sequence that are subsequently cleaved into multiple copies of the allergen protein. NPAs bind small lipids such as fatty acids and retinol (Vitamin A) and probably transport these sensitive and insoluble compounds between the tissues of the worms. Nematodes cannot synthesize these lipids, so NPAs may also be crucial for extracting nutrients from their hosts. They may also be involved in altering immune responses by controlling the lipids by which the immune and inflammatory cells communicate. We describe the molecular structure of one unit of an NPA, the well-known ABA-1 allergen of Ascaris and find its structure to be of a type not previously found for lipid-binding proteins, and we describe the unusual sites where lipids bind within this structur

    Developing international business relationships in a Russian context

    Get PDF
    The collapse of the former Soviet Union has opened up a wealth of business opportunities for companies seeking new markets in the Russian Federation. Despite this, firms intending to do business in Russia have found themselves hampered by cultural differences in business practices and expectations. As Russia integrates into the global economy, understanding such practices and the managerial mindset of business people is crucial for managers who hope to navigate Russia's complex markets. This study draws on the trust literature and adopts quantitative tools to deconstruct the Russian 'Sviazi' system of social capital business networking. We develop a model isolating three dimensions of Sviazi: one an affective or emotional component; the second, a conative component; and the third, a cognitive component. The model provides a useful guide for helping foreign firms to succeed in Russia, while also serving as a basis for further research in the field. Keywords

    The Economics of Agricultural R&D

    Get PDF
    Agricultural research has transformed agriculture and in doing so contributed to the transformation of economies. Economic issues arise because agricultural research is subject to various market failures, because the resulting innovations and technological changes have important economic consequences for net income and its distribution, and because the consequences are difficult to discern and attribute. Economists have developed models and measures of the economic consequences of agricultural R&D and related policies in contributions that relate to a very broad literature ranging across production economics, development economics, industrial organization, economic history, welfare economics, political economy, econometrics, and so on. A key general finding is that the social rate of return to investments in agricultural R&D has been generally high. Specific findings differ depending on methods and modeling assumptions, particularly assumptions concerning the research lag distribution, the nature of the research-induced technological change, and the nature of the markets for the affected commodities
    corecore