Small-angle x-ray scattering of high- and low-affinity heparin

Khorramian, B.A.; Stivala, Salvatore

doi:10.1016/0003-9861(86)90597-7

Cited by 23 publications

(12 citation statements)

References 36 publications

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“…6). The dose of cimetidine (100 mg/kg) used in our studies has been shown previously to be effective in blocking the renal uptake of organic cations (23,24). Thus, our results suggest that the uptake of the FITClabeled UFH and LMWH is due to an organic anion transport mechanism, and not a cation transport mechanism.…”

Section: Effect Of Renal Tubular Blockade On the Uptake Of Fitc-labelsupporting

confidence: 50%

“…Micropuncture studies have not been reported for LMWH. The restricted transglomerular passage of heparin can be attributed to a combination of its molecular shape and negative electrostatic charge (24). The wall of the glomerular capillary contains a number of fixed polyanions, including heparan sulphate (25), which can present an electrostatic barrier to the free passage of other polyanionic species, such as heparin.…”

Section: Discussionmentioning

confidence: 99%

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Localization of heparin and low-molecular-weight heparin in the rat kidney

Young

Douros²,

Podor³

et al. 2004

Thromb Haemost

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Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are cleared, at least in part, by the kidneys through a poorly understood process. This study was undertaken to explore the mechanism of renal clearance of these drugs. Rats were given fluorescein-5-isothiocyanate (FITC)-labeled UFH or LMWH intravenously. At intervals after injection, rats were euthanized and the kidneys were harvested and subjected to immunohistochemical analysis and fluorescence microscopy. Both UFH and LMWH were localized to renal tubular cells and no immunoperoxidase staining or fluorescence was detected in glomeruli. Autoradiography demonstrated similar intracellular distribution of radio-labeled UFH suggesting that this phenomenon is independent of the method used to label heparin. Fluorescence in the tubules increased as a function of time after UFH injection, but reached a plateau after LMWH injection suggesting that the rate of renal tubular uptake depends on the molecular size of the heparin. When administered prior to FITC-labeled UFH or LMWH, probenecid, a renal organic anion inhibitor, decreased the renal tubular uptake of the heparins, whereas cimetidine, a renal organic cation inhibitor, had no effect. These findings suggest that renal excretion of UFH and LMWH primarily reflects tubular uptake via an organic anion transport mechanism.

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Section: Effect Of Renal Tubular Blockade On the Uptake Of Fitc-labelsupporting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Localization of heparin and low-molecular-weight heparin in the rat kidney

Young

Douros²,

Podor³

et al. 2004

Thromb Haemost

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“…This analysis, though valid, ignores the potential impact of differences in the structure and stiffness of heparin variants on protamine binding and activity. Heparin exists in aqueous solution as an extended helix with a persistence length, which provides a measure of the stiffness (or structural order) of a polymer, of 2.11 nm, or approximately five disaccharide units . This represents ∼15% of the average length of UFH, but ∼45–50% of that of LMWH.…”

Section: Results and Discussionmentioning

confidence: 99%

A Polymer Therapeutic Having Universal Heparin Reversal Activity: Molecular Design and Functional Mechanism

Kalathottukaren

Abbina

et al. 2017

Biomacromolecules

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Heparins are widely used to prevent blood clotting during surgeries and for the treatment of thrombosis. However, bleeding associated with heparin therapy is a concern. Protamine, the only approved antidote for unfractionated heparin (UFH) could cause adverse cardiovascular events. Here, we describe a unique molecular design used in the development of a synthetic dendritic polycation named as universal heparin reversal agent (UHRA), an antidote for all clinically used heparin anticoagulants. We elucidate the mechanistic basis for the selectivity of UHRA to heparins and its nontoxic nature. Isothermal titration calorimetry based binding studies of UHRAs having different methoxypolyethylene glycol (mPEG) brush structures with UFH as a function of solution conditions, including ionic strength, revealed that mPEG chains impose entropic penalty to the electrostatic binding. Binding studies confirm that, unlike protamine or N-UHRA (a truncated analogue of UHRA with no mPEG chains), the mPEG chains in UHRA avert nonspecific interactions with blood proteins and provide selectivity toward heparins through a combined steric repulsion and Donnan shielding effect (a balance of F and F). Clotting assays reveal that UHRA with mPEG chains did not adversely affect clotting, and neutralized UFH over a wide range of concentrations. Conversely, N-UHRA and protamine display intrinsic anticoagulant activity and showed a narrow concentration window for UFH neutralization. In addition, we found that mPEG chains regulate the size of antidote-UFH complexes, as revealed by atomic force microscopy and dynamic light scattering studies. UHRA molecules with mPEG chains formed smaller complexes with UFH, compared to N-UHRA and protamine. Finally, fluorescence and ELISA experiments show that UHRA disrupts antithrombin-UFH complexes to neutralize heparin's activity.

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“…Historically, it is best known as an anticoagulant, functioning by binding to antithrombin III, which decreases the activation of thrombin and therefore the ability of blood to clot [2,3]. Purification and fractionation of clinical heparin alters its molecular weight (MW), ''standard heparin'' having a molecular weight of about 12 kDa, and ''low-MW heparin'' having a molecular weight of 3-8 kDa [4].…”

mentioning

confidence: 99%

Determination of molecular weight of heparin by size exclusion chromatography with universal calibration

Guo

Condra

Kimura

et al. 2003

Analytical Biochemistry

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The molecular weight (MW) of heparin can be accurately determined by size exclusion chromatography using ''universal calibration.'' A universal calibration curve was constructed for Superose 12 with standard pullulan samples and verified using characterized ficoll fractions. This calibration yielded the correct MW of heparin as determined by light scattering, when the ionic strength of the mobile phase was maintained over 1.0 M. Sodium poly(styrenesulfonate) samples were not suitable standards because of adsorption at high salt concentration and repulsion from the packing material at low ionic strength. The extraordinarily high charge density of heparin leads to the need for high salt concentration to screen such repulsions.

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Small-angle x-ray scattering of high- and low-affinity heparin

Cited by 23 publications

References 36 publications

Localization of heparin and low-molecular-weight heparin in the rat kidney

Localization of heparin and low-molecular-weight heparin in the rat kidney

A Polymer Therapeutic Having Universal Heparin Reversal Activity: Molecular Design and Functional Mechanism

Determination of molecular weight of heparin by size exclusion chromatography with universal calibration

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