In addition to generating movement, skeletal muscle may have a function as a secretory organ. The aim of the present study was to identify novel proteins with signaling capabilities secreted from skeletal muscle cells. IL-7 was detected in media conditioned by primary cultures of human myotubes differentiated from satellite cells, and concentrations increased with incubation time. By immunoblotting and real-time RT-PCR IL-7 expression was confirmed at both protein and mRNA levels. Furthermore, with immunofluorescence and specific antisera, multinucleated myotubes were found to coexpress IL-7 and myosin heavy chain. During differentiation of human myotubes from satellite cells, IL-7 expression increased at mRNA and protein levels. In contrast, mRNA expression of the IL-7 receptor was 80% lower in myotubes compared with satellite cells. Incubations with recombinant IL-7 under differentiation conditions caused approximately 35% reduction in mRNA for the terminal myogenic markers myosin heavy chain 2 (MYH2) and myogenin (MYOG), suggesting that IL-7 may act on satellite cells to inhibit development of the muscle fiber phenotype. Alternative routes of cell development were investigated, and IL-7 increased migration of satellite cells by 40% after 48 h in a Transwell system, whereas cell proliferation remained unchanged. In vivo, real-time RT-PCR analysis of musculus vastus lateralis (n = 10) and musculus trapezius (n = 7) biopsies taken from male individuals undergoing a strength training program demonstrated that after 11 wk mean IL-7 mRNA increased by threefold (P = 0.01) and fourfold (P = 0.04), respectively. In conclusion, we have demonstrated that IL-7 is a novel myokine regulated both in vitro and in vivo, and it may play a role in the regulation of muscle cell development.

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O. Security Policy Considerations. Cooperation and Conflict, UI, 1971, 31-8. The following is an attempt to define more precisely that concept of security which has been customarily utilized in security policy research. After commencing with a definition of security as 'the likelihood of surviving', some of the preconditions for a high national security and the prospects for a national security policy within the future international system are discussed. Among other things an attempt is made to indicate how a rational security policy will imply a gradual relinquishing of national autonomy together with efforts aimed at reducing one-sided dependence situations among pairs of nations.

A theory of public policy cannot be based solely on the theory of market failure. It also requires a theory of nonrnarket (or government) failure, argues the American economist Charles Wolf, Jr. In an important article from 1979 Wolf presents the outlines of such a theory of nonmarket failure The present article critically discusses Wolfs theory and tries to demonstrate that even his theory is not sufficiently adequate. One point made is that nonmarkets cannot be directly compared to markets since they do not represent one elemental decision process, as markets do. A nonmarket is a composite decision system. Another point that is advanced is that there are more decision systems than markets and nonmarkets, and that a complete theory of public policy must reflect this fact. Here two such additional systems are suggested cultures and networks.