scholarly journals Dalteparin, a low-molecular-weight heparin, promotes angiogenesis mediated by heparin-binding VEGF-A in vivo

Apmis ◽  
2010 ◽  
Vol 118 (12) ◽  
pp. 949-957 ◽  
Author(s):  
KLAS NORRBY ◽  
ARVID NORDENHEM
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Heparin Binding

Novel concatameric heparin-binding peptides reverse heparin and low-molecular-weight heparin anticoagulant activities in patient plasma in vitro and in rats in vivo

Blood ◽  
2004 ◽  
Vol 103 (4) ◽  
pp. 1356-1363 ◽  
Author(s):  
Barbara P. Schick ◽  
David Maslow ◽  
Adrianna Moshinski ◽  
James D. San Antonio
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Tandem Repeats ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Heparin Binding ◽  
High Affinity ◽  
Binding Peptides

Abstract Patients given unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) for prophylaxis or treatment of thrombosis sometimes suffer serious bleeding. We showed previously that peptides containing 3 or more tandem repeats of heparin-binding consensus sequences have high affinity for LMWH and neutralize LMWH (enoxaparin) in vivo in rats and in vitro in citrate. We have now modified the (ARKKAAKA)n tandem repeat peptides by cyclization or by inclusion of hydrophobic tails or cysteines to promote multimerization. These peptides exhibit high-affinity binding to LMWH (dissociation constant [Kd], ≈ 50 nM), similar potencies in neutralizing anti–Factor Xa activity of UFH and enoxaparin added to normal plasma in vitro, and efficacy equivalent to or greater than protamine. Peptide (ARKKAAKA)3VLVLVLVL was most effective in all plasmas from enoxaparin-treated patients, and was 4- to 20-fold more effective than protamine. Several other peptide structures were effective in some patients' plasmas. All high-affinity peptides reversed inhibition of thrombin-induced clot formation by UFH. These peptides (1 mg/300 g rat) neutralized 1 U/mL anti–Factor Xa activity of enoxaparin in rats within 1 to 2 minutes. Direct blood pressure and heart rate measurements showed little or no hemodynamic effect. These heparin-binding peptides, singly or in combination, are potential candidates for clinical reversal of UFH and LMWH in humans.

Novel Design of Peptides to Reverse the Anticoagulant Activities of Heparin and other Glycosaminoglycans

2001 ◽  
Vol 85 (03) ◽  
pp. 482-487 ◽  
Author(s):  
Joel Gradowski ◽  
James San Antonio ◽  
Jose Martinez ◽  
Barbara Schick
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Heparin Binding ◽  
Antifactor Xa ◽  
Novel Design

SummaryPatients undergoing anticoagulation with unfractionated heparin, low molecular weight heparin, or danaparoid may experience excess bleeding which requires reversal of the anticoagulant agent. Protamine is at present the only agent available for reversal of unfractionated heparin. Protamine is not effective in patients who have received low molecular weight heparin or danaparoid. We have developed a series of peptides based on consensus heparin binding sequences (Verrecchio et al., J Biol Chem 2000; 275: 7701-7707) that are capable of neutralizing the anti-thrombin activity of unfractionated heparin in vitro, the antifactor Xa activity of unfractionated heparin, Enoxaparin (Lovenox) and danaparoid (Orgaran) in vitro and the anti-Factor Xa activity of Enoxaparin in vivo in rats. These peptides may serve as alternatives for Protamine reversal of UFH and may be useful for neutralization of enoxaparin and danaparoid in humans.

Effects of Unfractionated and Low Molecular Weight Heparins on Platelet Thromboxane Biosynthesis “In Vivo”

1994 ◽  
Vol 72 (06) ◽  
pp. 942-946 ◽  
Author(s):  
Raffaele Landolfi ◽  
Erica De Candia ◽  
Bianca Rocca ◽  
Giovanni Ciabattoni ◽  
Armando Antinori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Primary Source ◽  
In Vivo Studies ◽  
Low Molecular Weight ◽  
Heparin Administration ◽  
To Receive

SummarySeveral “in vitro” and “in vivo” studies indicate that heparin administration may affect platelet function. In this study we investigated the effects of prophylactic heparin on thromboxane (Tx)A2 biosynthesis “in vivo”, as assessed by the urinary excretion of major enzymatic metabolites 11-dehydro-TxB2 and 2,3-dinor-TxB2. Twenty-four patients who were candidates for cholecystectomy because of uncomplicated lithiasis were randomly assigned to receive placebo, unfractionated heparin, low molecular weight heparin or unfractionaed heparin plus 100 mg aspirin. Measurements of daily excretion of Tx metabolites were performed before and during the treatment. In the groups assigned to placebo and to low molecular weight heparin there was no statistically significant modification of Tx metabolite excretion while patients receiving unfractionated heparin had a significant increase of both metabolites (11-dehydro-TxB2: 3844 ± 1388 vs 2092 ±777, p <0.05; 2,3-dinor-TxB2: 2737 ± 808 vs 1535 ± 771 pg/mg creatinine, p <0.05). In patients randomized to receive low-dose aspirin plus unfractionated heparin the excretion of the two metabolites was largely suppressed thus suggesting that platelets are the primary source of enhanced thromboxane biosynthesis associated with heparin administration. These data indicate that unfractionated heparin causes platelet activation “in vivo” and suggest that the use of low molecular weight heparin may avoid this complication.

Comparison of the Non-Specific Binding of Unfractionated Heparin and Low Molecular Weight Heparin (Enoxaparin) to Plasma Proteins

1993 ◽  
Vol 70 (04) ◽  
pp. 625-630 ◽  
Author(s):  
Edward Young ◽  
Benilde Cosmi ◽  
Jeffrey Weitz ◽  
Jack Hirsh
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Plasma Proteins ◽  
Low Molecular Weight Heparin ◽  
Specific Binding ◽  
Anticoagulant Activity ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Heparin Binding ◽  
Fixed Amount

SummaryThe non-specific binding of anticoagulantly-active heparin to plasma proteins may influence its anticoagulant effect. We used low affinity heparin (LAH) essentially devoid of anti-factor Xa activity to investigate the extent and possible mechanism of this non-specific binding. The addition of excess LAH to platelet-poor plasma containing a fixed amount of unfractionated heparin doubled the anti-factor Xa activity presumably because it displaces anticoagulantly-active heparin from plasma proteins. Although dextran sulfates of varying molecular weights also increased the anti-factor Xa activity, less sulfated heparin-like polysaccharides had no effect. These findings suggest that the ability to displace active heparin from plasma protein binding sites is related to charge and may be independent of molecular size. In contrast to its effect in plasma containing unfractionated heparin, there was little augmentation in anti-factor Xa activity when LAH was added to plasma containing low molecular weight heparin (LMWH), indicating that LMWH binds less to plasma proteins than unfractionated heparin. This concept is supported by studies comparing the anticoagulant activity of unfractionated heparin and LMWH in plasma with that in buffer containing antithrombin III. The anti-factor Xa activity of unfractionated heparin was 2-fold less in plasma than in the purified system. In contrast, LMWH had identical anti-factor Xa activity in both plasma and buffer, respectively. These findings may be clinically relevant because the recovered anti-factor Xa activity of unfractionated heparin was 33% lower in plasma from patients with suspected venous thrombosis than in plasma from healthy volunteers. The reduced heparin recovery in patient plasma reflects increased heparin binding to plasma proteins because the addition of LAH augmented the anti-factor Xa activity. In contrast to unfractionated heparin, there was complete recovery of LMWH added to patient plasma and little increase of anti-factor Xa activity after the addition of LAH. These findings may explain why LMWH gives a more predictable dose response than unfractionated heparin.

Neutralization of a Low Molecular Weight Heparin (LHN-1) and Conventional Heparin by Protamine Sulfate in Rats

1986 ◽  
Vol 56 (03) ◽  
pp. 318-322 ◽  
Author(s):  
V Diness ◽  
P B Østergaard
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Thrombus Formation ◽  
Experimental Models ◽  
Protamine Sulfate ◽  
Low Molecular Weight ◽  
Antithrombotic Effect ◽  
Higher Doses

SummaryThe neutralization of a low molecular weight heparin (LHN-1) and conventional heparin (CH) by protamine sulfate has been studied in vitro and in vivo. In vitro, the APTT activity of CH was completely neutralized in parallel with the anti-Xa activity. The APTT activity of LHN-1 was almost completely neutralized in a way similar to the APTT activity of CH, whereas the anti-Xa activity of LHN-1 was only partially neutralized.In vivo, CH 3 mg/kg and LHN-1 7.2 mg/kg was given intravenously in rats. The APTT and anti-Xa activities, after neutralization by protamine sulfate in vivo, were similar to the results in vitro. In CH treated rats no haemorrhagic effect in the rat tail bleeding test and no antithrombotic effect in the rat stasis model was found at a protamine sulfate to heparin ratio of about 1, which neutralized APTT and anti-Xa activities. In LHN-1 treated rats the haemorrhagic effect was neutralized when APTT was close to normal whereas higher doses of protamine sulfate were required for neutralization of the antithrombotic effect. This probably reflects the fact that in most experimental models higher doses of heparin are needed to induce bleeding than to prevent thrombus formation. Our results demonstrate that even if complete neutralization of APTT and anti-Xa activities were not seen in LHN-1 treated rats, the in vivo effects of LHN-1 could be neutralized as efficiently as those of conventional heparin. The large fall in blood pressure caused by high doses of protamine sulfate alone was prevented by the prior injection of LHN-1.

scholarly journals Inhibition of Plasmin Generation in Plasma By Heparin, Low Molecular Weight Heparin and a Covalent Antithrombin-Heparin Complex (ATH)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4217-4217
Author(s):  
Gabriela Chang ◽  
Helen M. Atkinson ◽  
Leslie R. Berry ◽  
Anthony K.C. Chan
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Low Molecular Weight Heparin ◽  
Conflicts Of Interest ◽  
Area Under The Curve ◽  
Low Molecular Weight ◽  
Plasminogen Activator Inhibitor 1 ◽  
Significant Difference

Abstract Introduction: Unfractionated heparin (UFH) and low molecular weight heparin (LMWH) are widely used anticoagulants for thrombosis treatment. However, these anticoagulants have limitations such as increased bleeding, variable dose response, required frequent monitoring, and, in the case of LMWH, inability to inhibit thrombin. This has led to the development of a covalent complex of antithrombin and heparin (ATH), which has been shown to overcome many of these shortcomings. ATH has faster rates of inhibition of many coagulation factors, is able to inhibit clot-bound thrombin, and is a more effective inhibitor of both venous and arterial thrombosis in animal models. Moreover, in a rabbit thrombosis model, ATH has been shown to decrease clot mass and fibrin accretion, while the contrary was observed for UFH. From these observations, it was suggested that ATH may enhance fibrin breakdown and thus led to investigations into the effects of UFH and ATH on fibrinolysis. In vitro studies have shown that UFH enhances antithrombin inhibition of plasmin. In addition, ATH displays a slightly greater inhibition of plasmin generation and activity. Such studies were conducted in purified systems, in the absence of other plasmin inhibitors naturally present in plasma. Therefore, the aim of the present study was to compare the effects of UFH, LMWH, and ATH on plasmin generation in plasma. Methods: At 37°C tissue plasminogen activator (tPA) and soluble fibrin fragments (fib) were added to normal adult pooled platelet poor plasma supplemented with 0.35, 0.7, 1.4, or 2.1 U anti-Xa/ml UFH, LMWH, or ATH, to initiate plasmin generation (8.93nM tPA and 300µg/ml fib). At various time points, subsamples were mixed with excess plasminogen activator inhibitor 1 (PAI-1) (55.12nM) to stop further plasmin generation. The plasmin concentration at each time point was determined using a plasmin-specific chromogenic substrate and a standard curve produced from purified plasmin. Results: Comparisons of mean area under the curve (AUC) for plasmin generation displayed a significant decrease in plasmin generation in the presence of all three anticoagulants at all doses tested (p<0.05). Comparing the anticoagulants at similar doses, plasmin generation was significantly decreased in the presence of ATH (15384.66±1930.23nM/min) compared to LMWH (23892.28±3090.54nM/min) at 0.7 U/ml (p<0.05). At a dose of 1.4 U/ml, there was significantly less plasmin generated, over time, in the presence of UFH (20089.49±3022.1623nM/min) and ATH (19273.86±1805.7323nM/min) when compared to LMWH (24743.18±1265.1023nM/min) (p<0.05). There was no significant difference in plasmin inhibition between UFH and ATH at any of the doses tested. Conclusion: The present study supports previous findings that UFH and ATH can facilitate antithrombin inhibition of plasmin. It is also observed that LMWH catalyzes the inhibition of plasmin by antithrombin but possibly to a lesser extent. These findings suggest that ATH has a similar inhibitory effect on plasmin generation and activity in plasma compared to UFH, despite its overall superior anticoagulant properties. Therefore, previous in vivo observations displaying decrease in clot mass with administration of ATH was due to its enhanced anticoagulant abilities and not fibrinolysis enhancement. These findings add to our understanding of ATH mechanisms of action and aid in its development for clinical use. Disclosures No relevant conflicts of interest to declare.

In Vivo Studies On The Inhibition Of Coagulation By Fractionated Heparin

1981 ◽  
Author(s):  
U Schmitz-Huebner ◽  
L Balleisen ◽  
F Asbeck ◽  
J van de Loo
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Gel Filtration ◽  
In Vivo Studies ◽  
Low Molecular Weight ◽  
Chromogenic Substrate ◽  
Serotonin Content ◽  
Heparin Activity ◽  
Heparin Fractions

Recent investigations suggest that low molecular weight heparin may have advantages over conventional heparin with regard to the prevention of venous thrombosis and haemorrhagic side effects.High (HMW) and low (LMW) molecular weight heparin fractions with mean MWs of 16,000 and 8,800 respectively, obtained by gel filtration chromatography of sodium mucosal heparin (B. Braun Melsungen), were injected subcutaneously into six volunteers and compared with the unfractionated substance in a cross-over trial. Doses of 5,000 U were administered twice daily over a period of three days and heparin activity was controlled before injection and 2,4,8 hours afterwards by means of the APTT, the anti-Xa clotting test and a chromogenic substrate assay. In addition, the in vivo effect of fractionated heparin on platelet function was examined. The results show that the LMW fraction induced markedly higher anti-Xa activity than the other preparations. At the same time, APTT results did not significantly differ. Unfractionated heparin and the HMW fraction enhanced ADP-induced platelet aggregation and collagen-mediated MDA-production, while the LMW fraction hardly affected these assays, but potently inhibited thrombin-induced MDA production. All heparin preparations stimulated the release of PF IV, whereas the serotonin content of platelets determined at the same time increased.It is concluded that s.c. injections of LMW heparin induce relatively high levels of anti-Xa activity without leading to sensitive platelet activation or to major effects on overall clotting tests.

PHARMACOKINETICS OF A LOW MOLECULAR WEIGHT HEPARIN (KABI 2165, FRAGMIN) ATFER INTRAVENOUS AND SUBCUTANEOUS ADMINISTRATION IN HUMAN VOLUNTEERS AND ITS IN VIVO NEUTRALIZATION BY PROTAMINE SULFATE

1987 ◽  
Author(s):  
J Albada ◽  
K K Nieuwenhuis ◽  
J J Sixma
Keyword(s):  
Molecular Weight ◽  
Healthy Volunteers ◽  
Half Life ◽  
Low Molecular Weight Heparin ◽  
Subcutaneous Administration ◽  
Low Molecular Weight ◽  
Protamine Sulphate ◽  
Original Curve ◽  
Rebound Phenomenon

Pharmacokinetics of a low molecular weight heparin (LMWH) were studied in healthy volunteers. After an intravenous bolus injection of 5000 anti-Xa U in 5 healthy volunteers anti Xa activity disappeared according to the combination of saturable and a linear mechanism, preceded by a rapid initial disappearance. The apparent half-life of the anti Xa activity is about twice as long as that of standard heparin. In another set of experiments 5000 anti Xa U of LMWH were immediately followed by 50 mgr of Protamine Sulphate (PS). The curve of the anti Xa-activity parallelled the original curve at a level of about 30-40%. No rebound phenomenon was observed. The same dose of the LMWH followed by 100 mg of PS resulted in an anti Xa disappearance curve at an obvious higher level of about 50%. Also at this dose no rebound phenomenon was noticed.A continuous infusion of 10.000 anti Xa U/24 h during 10 hours was followed by 15.000 anti Xa U/24 h for another 10 hours after which the dose was raised to 20.000 anti Xa U/24 h for another 10 hours. Only the first infusion period resulted in a plateau fase. At the end of these experiments anti Xa activity was neutralized by 50 mg P.S. i.v. resulting in the disappearance of less than 50% of anti Xa activity. After subcutaneous administration of 15.000 anti Xa U (corresponding to the dose for i.v. treatment per day with this LMWH) peak levels of 1,1-1,8 anti Xa were reached after 3-4 hours. Supra-optimal anti Xa levels (higher than 0.9) were observed in all volunteers during a period of 5 hours. After 24 hours in none of the volunteers any anti Xa-activity could be detected.Conclusions:In contrast to previous reports pharmacokinetics of this LMWH do not essentially differ from those of standard heparin apart from its longer half-life and its high bioavialability after subcutaneous injection.

Enhancing Effects of Heparin/Low Molecular Weight Heparin/Heparan Sulfate on Antigen Presentation and Antigen-Specific Cytotoxic T Lymphocyte (CTL) Induction by Monocyte-Derived Dendritic Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3816-3816
Author(s):  
Asuka Sekiguchi ◽  
Miwako Narita ◽  
Toshio Yano ◽  
Naoko Sato ◽  
Anri Saito ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Heparan Sulfate ◽  
Antigen Presentation ◽  
Binding Sites ◽  
Low Molecular Weight Heparin ◽  
Target Cells ◽  
Low Molecular Weight ◽  
Heparin Binding ◽  
Antigen Presenting ◽  
Ctl Induction

Abstract Heparin is bound with heparin-binding sites on certain cells, which induces proliferation and differentiation signals. In addition, heparin is bound with heparin-binding domains of various cytokines, which enhances the interaction between cytokines and target cells. Monocytes have been demonstrated to posses heparin-binding sites on cell surfaces. In the present study, we investigated the effects of heparin (including low molecular weight heparin) and heparan sulfate on antigen presentation and antigen-specific CTL induction of monocyte-derived DCs. Peripheral blood CD14+ cells were cultured to generate immature and mature DCs with various concentrations of heparin, low molecular weight heparin or heparan sulfate. Cultured cells were analyzed for DC-associated surface phenotypes by flow cytometry and evaluated for allogeneic antigen presenting ability by mixed leukocyte culture. In order to evaluate the effects of heparin on monocyte-derived DCs to generate antigen-specific CTL, DCs were generated from HLA-A2402 donors by serum-free culture with heparin, transfected with in vitro transcribed WT-1 mRNA on day 6 and cultured with the addition TNF-α/IL-1α/IL-6/IFN-γ/PGE2 for further 1 day. WT-1 mRNA-transfected DCs were used for priming autologous lymphocytes in co-culture at the stimulator:responder ratio of 1:10. Lymphocytes were primed with the same DCs 2-3 times in the interval of 5-7 days. CD8+ T cells were separated and used as effector cells in 51Cr-release assay. WT-1 expressing and HLA-A24+ cell line MegO1 was used as target cells. In order to evaluate the association of MHC molecules in the cytotoxicity, 51Cr-lebelled target cells were treated with anti-MHC class I or class II monoclonal antibody before cytotoxicity assay. In order to evaluate the antigen specificity of the generated CTL, unlabelled target cells were added to the cytotoxicity assay. By the addition of heparin, the expression of CD1a and CD80 on both immature and mature DCs was markedly enhanced and the allogeneic antigen presenting ability was elevated in both immature and mature DCs. By the addition of low molecular weight heparin, the expression of CD1a was enhanced and antigen presenting ability was elevated also. By the addition of heparan sulfate, similar results of elevated antigen presentation were obtained. By the priming of lymphocytes with WT-1 mRNA transfected DCs generated from monocytes by the serum-free culture with heparin, cytotoxic capability against WT-1 expressing target cells was demonstrated in the primed lymphocytes. The cytotoxic capability of the lymphocytes was blocked by the treatment of the target cells with anti-MHC class I monoclonal antibody and the addition of unlabelled target cells in the cytotoxicity reaction. The present study demonstrated that heparin/low molecular weight heparin/heparan sulfate could enhance the antigen presentation and antigen-specific CTL induction of monocyte-derived DCs. These findings suggest the usefulness of heparin for generating efficient DCs for DC-based immunotherapy and the involvement of heparan sulfate in immunological defense mechanism.

Sign in / Sign up

Export Citation Format

Share Document