The insulin-like growth factors ( @entity442 and @entity5100 ) are almost completely bound in the circulation to specific binding proteins (IGFBPs). These IGFBPs appear to play a pivotal role in maintaining circulating levels and modulating the delivery of the IGFs to the tissues. A large proportion of the circulating IGFs are bound with high affinity to one of the binding proteins. @entity2301 . The mechanism by which these IGFs are transferred from the circulatory pool to the tissue receptors is at present unclear. Recent studies in late pregnancy have demonstrated the presence of specific proteases which may modify the IGFBPs such that their affinities for the IGFs are reduced. In this paper, we have demonstrated the presence of a heat-sensitive cation-dependent proteolytic enzyme specific for @entity2301 in the serum of five severely ill @entity1 . The activity of this protease was found to vary in these @entity1 , becoming more apparent during fasting than when studied after commencement of parenteral nutrition, indicating that one of the influencing factors in the activity of this protease is the nutritional intake of the @entity1 . Age- and sex-matched healthy adults were also studied in a similar protocol, but no proteolytic modification of any of the IGFBPs was found in any of the samples examined. As the levels of both @entity442 and @entity5100 were found to be low in the @entity1 , the presence of a circulatory protease suggests that this may be an adaptive response to increase the bioavailability of the IGFs and possibly to improve the @entity1568 retention and counter the catabolic state in severe @entity221 .

The induction of a specific protease for XXXX in the circulation during severe @entity221 .

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity1568 :: ('MESH:D009584', 'Chemical') :: ['nitrogen'] @entity2301 :: ('3486', 'Gene') :: ['IGFBP-3'] @entity442 :: ('3479', 'Gene') :: ['IGF-I'] @entity5100 :: ('3481', 'Gene') :: ['IGF-II'] @entity221 :: ('MESH:D005334', 'Disease') :: ['illness']
@entity2301 :: (3486,Gene) :: ['insulin-like growth factor binding protein-3']
