Plasma Heparin Levels in Normal Man

Abstract

With the technical assistance of Anne Dudley T HE DETERMINATION of the level of circulating endogenous heparin is important, since heparin may normally function to keep the blood in a fluid state, and it also probably plays a major role in the clearing of alimentary lipemia from the bloodstream. Unfortunately, methods for the extraction of native heparin are not only difficult and tedious, but the end-product includes other mucopolysaccharides that interfere with assays based upon metachromatic technics.' On the other hand, coagulation tests, such as the protamine titration and toluidine blue procedures, are not an index of the amount of heparin but rather indicators of the equilibrium between the systems of factors favoring or inhibiting blood clotting.2 A relatively simple procedures based upon thrombin neutralization is available, but it is only discriminating enough to disclose marked increases in heparin levels. There are excellent methods4 for measuring the levels of injected, free heparin, but these do not afford information about the quantity of endogenous plasma heparin, which. with rare exceptions, is always protein-bound.These various difficulties, and the failure to appreciate them, have led to marked discrepancies in the results reported in studies of circulating heparin. Some responsible investigators4 imply that heparin is not normally present in human plasma, whereas others5 have reported very high levels. It

Human lactoferricin derived di-peptides deploying loop structures induce apoptosis specifically in cancer cells through targeting membranous phosphatidylserine

“…Fadnes et al [14] found that the anticancer activity of bovine LFcin was inhibited by heparan sulfate on the surface of tumor cells. In our studies the di-peptides derived from hLFcin were however not influenced in their activity by exogenous heparin or chondroitin sulfate at physiological concentrations of 1-10 µg/ml [66,67]. Thus neither heparin nor CS, which is increased on the surface of melanoma cells, seems to significantly protect the cell from the interaction with the studied di-peptides.…”

Pathogenic Factors in Vascular Dementia and Alzheimer’s Disease

“…The levels of heparin activity were close to those found previously [75]. Thus, there is little reason to doubt any longer the existence of endogenous heparin activity in human blood.…”

“…Thus, proteolysis of the precipitated plasma proteins is necessary before endogenous heparin activity can be identified and quantitated. Using this method, plasma heparin levels in 153 male and 104 female nonfasting adults ranged from 1 to 2.4 mg/l [75]. The results were statistically highly significant and demonstrated that lower endogenous plasma heparin levels correlated with higher cholesterol and low-density lipoprotein serum levels.…”

Isolation and Characterization of Heparin from Human Lung

“…Human tissue heparin-like activity, defined only by the presence of anticoagulant function and metachromasia, has been observed in mucopolysaccharidecontaining fractions extracted from lung (6, 7), liver (8), skin (9), and blood (10,11). However, in no instance has the material been assessed for binding to human antithrombin.…”