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81.
Horlings HM Bergamaschi A Nordgard SH Kim YH Han W Noh DY Salari K Joosse SA Reyal F Lingjaerde OC Kristensen VN Børresen-Dale AL Pollack J van de Vijver MJ 《Nature genetics》2008,40(7):809; author reply 810-809; author reply 812
82.
Human skin is permanently exposed to microorganisms, but rarely infected. One reason for this natural resistance might be
the existence of a ‘chemical barrier’ consisting in constitutively and inducibly produced antimicrobial peptides and proteins
(AMPs). Many of these AMPs can be induced in vitro by proinflammatory cytokines or bacteria. Apart from being expressed in vivo in inflammatory lesions, some AMPs are also focally expressed in skin in the absence of inflammation. This suggests that
non-inflammatory stimuli of endogenous and/or exogenous origin can also stimulate AMP synthesis without inflammation. Such
mediators might be ideal ‘immune stimulants’ to induce only the innate antimicrobial skin effector molecules without causing
inflammation.
Received 9 August 2005; received after revision 21 October 2005; accepted 16 November 2005 相似文献
83.
Phytanic acid is a branched-chain fatty acid that accumulates in a variety of metabolic disorders. High levels of phytanic
acid found in patients can exceed the millimolar range and lead to severe symptoms. Degradation of phytanic acid takes place
by α-oxidation inside the peroxisome. A deficiency of its breakdown, leading to elevated levels, can result from either a
general peroxisomal dysfunction or from a defect in one of the enzymes involved in α-oxidation. Research on Refsum disease,
belonging to the latter group of disorders and characterized by a deficiency of the first enzyme of α-oxidation, has extended
our knowledge of phytanic acid metabolism and pathology of the disease greatly over the past few decades. This review will
centre on this research on phytanic acid: its origin, the mechanism by which its α-oxidation takes place, its role in human
disease and the way it is produced from phytol.
Received 4 October 2005; received after revision 24 February 2006; accepted 26 April 2006 相似文献
84.
85.
86.
Horses damp the spring in their step. 总被引:6,自引:0,他引:6
The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb. 相似文献
87.
A rapid process of hybridisation of man and technology, organisation and technology and society and technology is currently
sweeping the world. This process requires a way of (scientific) thinking that takes hybrid systems as the starting point.
Such an approach makes it increasingly important for hybrid systems to be interlinked, enabling them to exchange and share
information through these links. This linking of (hybrid) systems to enable them to exchange and share information can also
be denoted as the realisation of interoperability between (hybrid) systems. Five principles from Luhmann’s systems theory
can help us understand interoperability. Interoperability enables (hybrid) systems to join random coalitions and networks.
The network centric warfare concept is currently the basis for international efforts aimed at the development and application
of interoperability that would enable armed forces to act effectively and efficiently. This paper demonstrates what we can
learn from Luhmann’s system’s theory. 相似文献
88.
R E Hill J Favor B L Hogan C C Ton G F Saunders I M Hanson J Prosser T Jordan N D Hastie V van Heyningen 《Nature》1991,354(6354):522-525
89.
Structure of Arc repressor in solution: evidence for a family of beta-sheet DNA-binding proteins 总被引:15,自引:0,他引:15
The Arc repressor, which is involved in the switch between lysis and lysogeny of Salmonella bacteriophage P22, does not belong to any of the known classes of DNA-binding proteins. Mutagenesis studies show that the DNA-binding region is located in the 15 N-terminal amino-acid residues. We have now determined the three-dimensional structure of the Arc dimer from an extensive set of interproton-distance data obtained from 1H NMR spectroscopy. A priori, intra- and inter-monomer nuclear Overhauser effects (NOEs) cannot be distinguished for a symmetric dimer. But by using the homology with the Escherichia coli Met repressor we could interpret the NOEs unambiguously in an iterative structure refinement procedure. The final structure satisfies a large set of NOE constraints (1,352 for the dimer). It shows a strongly intertwined dimer, in which residues 8-14 of different monomers form an antiparallel beta-sheet. A model for the Arc repressor-operator complex can account for all available biochemical and genetic data. In this model two Arc dimers bind with their beta-sheet regions in successive major grooves on one side of the DNA helix, similar to the Met repressor interaction. Thus, Arc and Met repressors are members of the same family of proteins, which contain an antiparallel beta-sheet as the DNA-binding motif. 相似文献
90.
Characterization and molecular cloning of a bovine lentivirus related to human immunodeficiency virus 总被引:8,自引:0,他引:8
M A Gonda M J Braun S G Carter T A Kost J W Bess L O Arthur M J Van der Maaten 《Nature》1987,330(6146):388-391