Labeling of heparins

Fluorescent Labeling of Heparins and Related Polysaccharides Old Problems and New Solutions... 

Maximum labelling of heparin with F-D was achieved at 5 hours at 25 °C, pH 8.4. In the case of heparin, the efficiency of labelling was not dependent on molecular weight, but solely a function of the ratio of the concentrations of labelling reagent to monosaccharide subunit in the reaction mixture. Similar results were encountered in the labelling of dextrans of different molecular weight (9). 

The fluorescent labelling of heparin with F-D by this technique did not observably alter the biologic activity of the heparin as regards to its binding to antithrombin and catalysis of antithrombin s neutralization of activated coagulation factors. F-D labelled heparins also bound to other known heparin-binding proteins in a saturable and reversible manner, as demonstrated by the dot-blot assay technique (Figure 6). 

Sulfated amino (sulfoamino) groups occur naturally in heparin, and are readily produced synthetically by sulfation of amino groups. Such a reaction has been employed in the preparation of heparinoids, in the radio-labelling of heparin by lV-resulfation, and in the °S-sulfa-tion of nitrogen atoms of chitosan. ... 

Figure 2. The pH dependency of heparin labelling. The degree of labelling intensity of the final product was compared with the concomitantly measured solubility of the F-D labelling reagent.

Figure 4. The efficiency of labelling of N-blocked or nonblocked heparins with FITC versus F-D. See text for details of experiment a, F1TC b, F-D.

Table L Intensity of Labelling versus Heparin Anticoagulant Activity...

Probably, one of the most valuable advances in this field has dealt with the first chemoenzymatic synthesis of the stable isotope-enriched heparin from a uniformly double labelled 13C, 15N /V-acetylheparosan from E. coli K5. Heteronuclear, multidimensional nuclear magnetic resonance spectroscopy was employed to analyze the chemical composition and solution conformation of N-acety 1 hcparosan, the precursors, and heparin. Isotopic enrichment was found to provide well-resolved 13C spectra with the high sensitivity required for conformational studies of these biomolecules. Stable isotope-labelled heparin was indistinguishable from heparin derived from animal tissues and might be employed as a novel tool for studying the interaction of heparin with different receptors.30... 

The use of heparinized catheters for in vivo erythrocyte labelling with " Tc-pyrophosphate occasionally produces adverse reports, such as diminution of cardiac activity and increase of renal activity due to the formation of a technetium-heparin complex which localizes avidly in the kidneys. A few cases reported the possibility of reaction of radiopharmaceuticals with the components of a syringe or needle. 

Mallinckrodt Medical (1993) Product information for TechneScan PYP for the preparation of (Sn) pyrophosphate (PYP) injection solution. Mallinckrodt Medical, The Netherlands Pavel DG, Zimmer AM, Patterson VN (1977) In vivo labeling of red blood cells with " Tc a new approach to blood pool visualization. J Nucl Med 18 305-308 Porter WC, Dees SM, Freitas JE, Dworkin HJ (1983) Acid-citrate-dextrose compared with heparin in the preparation of in vivo/in vitro technetium-99m red blood cells. J Nucl Med 24 383-387... 

Wni i c phagocytic labeling of leucocytes proceeded for instance with a commercial suinTc-albumin colloid kit. ITie leucocytes were separated from 40 ml heparinized blood. ITie preparation appeared to be stable for 2-3 h after labeling. Imaging time was 30 min to 4 h post-administration. About 20 % of the labeled colloid remained unbound to the WBCs. The preparation contained approximately equal activities of granulocytes and monocytes [163. ... 

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