In-vitro testing of the effect of unfractionated heparin, and low molecular weight heparin on new generation thromboelastogram (TEG6s) and conventional coagulation assays

2017 ◽  
Author(s):  
Blesy Mathew
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
In Vitro Testing ◽  
Coagulation Assays ◽  
New Generation

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.

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.

Effect of Low-Molecular-Weight Heparin (Tinzaparin) and Unfractionated Heparin on Platelet Aggregation

1996 ◽  
Vol 2 (3) ◽  
pp. 209-212 ◽  
Author(s):  
Hanne B. Ravn ◽  
Claus Bregengaard ◽  
Henrik Vissinger ◽  
Per Østergaard ◽  
Jan Holst ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Platelet Aggregation ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Ex Vivo ◽  
Subcutaneous Administration ◽  
Low Molecular Weight ◽  
Pronounced Difference ◽  
Dose Dependent

A low-molecular-weight heparin (LMWH), when anti-IIa activity was compared. In the ex vivo part Tinzaparin, was compared with unfractionated heparin of the study, a significant enhancement of ADP-induced (UFH) for their effects on platelet aggregation in vitro and platelet aggregation was observed after i.v. administra ex vivo. Both heparins showed a dose-dependent proag- tion of both Tinzaparin and UFH with no difference in gregatory effect on ADP- and collagen-induced platelet potency. Subcutaneous administration of Tinzaparin in aggregation in vitro, but LMWH was less potent. The two different doses did not have any effect on platelet differences in potency between Tinzaparin and UFH de- activity. In conclusion, Tinzaparin appears, like other pended on how the compounds were compared. The most LMWHs, to have less proaggregatory effect on platelets pronounced difference was found when molar concentra- than UFH both in vitro and ex vivo.

Effects of a Low Molecular Weight Heparin (Fragmin®) and of Unfractionated Heparin on Coagulation Activation at the Site of Plug Formation In Vivo

1994 ◽  
Vol 72 (06) ◽  
pp. 831-835 ◽  
Author(s):  
Sabine Elchinger ◽  
Michael Wolzt ◽  
Malgorzata Nieszpaur-Los ◽  
Barbara Schneider ◽  
Klaus Lechner ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Bleeding Time ◽  
Venous Blood ◽  
Coagulation System ◽  
Low Molecular Weight ◽  
Coagulation Activation

SummaryThe clinical benefits of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) have been shown in many trials. However, the mode of action of heparin has not been fully elucidated. Thus, we wanted to study the effects of UFH and LMWH in vivo by measuring coagulation activation markers in blood obtained directly from a vascular injury site. In a double-blind, randomized, 3-way, cross-over study 18 healthy volunteers were given UFH (150 U/kg s.c.) and 2 doses of LMWH [35 U/kg s.c. (low dose, Id), 75 U/kg s.c. (high dose, hd)]. Prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT) and fibrinopeptide A (FPA) were measured in bleeding time blood and in venous blood before and after drug application. In addition, the effects of UFH and LMWH on in vitro coagulation tests were studied. Compared to base line, UFH and both IdLMWH and hdLMWH caused significant reductions of F1+2, TAT and FPA in bleeding time blood at 2 h. A marked effect of UFH and of hdLMWH was also seen at 5 h. The inhibition of FPA generation was more pronounced after hdLMWH compared to IdLMWH. In venous blood, UFH and LMWH caused reductions of F1+2, but not of TAT and FPA. In vitro, UFH predominantly affected the anti-IIa assays (activated partial thromboplastin time, thrombin time) and LMWH mainly the anti-Xa test system. Using a technique that investigates the activated coagulation system in vivo, a time- and dose dependent inhibitory effect of heparin on coagulation activation was detectable. Therefore, in our experimental setting a preferential inhibition of a particular portion of the coagulation system by one of the two heparin preparations was not detectable.

Markers of Hemostatic System Activation in Acute Deep Venous Thrombosis-Evolution during the First Days of Heparin Treatment

1993 ◽  
Vol 70 (06) ◽  
pp. 0909-0914 ◽  
Author(s):  
Keyword(s):  
Molecular Weight ◽  
Venous Thrombosis ◽  
Deep Venous Thrombosis ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Dose Adaptation ◽  
Heparin Treatment ◽  
Lung Scan

SummaryFibrin D-Dimer (D-Di), prothrombin activation fragment (F 1+2) and thrombin-antithrombin III complexes (TAT) were measured using ELISA procedures in the plasma of patients with an acute deep venous thrombosis (DVT), at presentation and on days 2, 6 and 10 after initiation of heparin treatment. Patients were randomly allocated into two treatment groups: 44 patients received adapted doses of continuous intravenous unfractionated heparin (UH) whereas 47 received 1 mg/kg every twelve hours of a low molecular weight heparin (enoxaparin) subcutaneously. A phlebography and a perfusion lung scan were performed before inclusion and on day 10. Failure of therapy (n = 9) was defined by venogram worsening or confirmed pulmonary embolism. Improvement (n = 44) or stationary state (n = 38) were defined by venogram evolution in the absence of new leg scan defects.At presentation, D-Di, F 1 + 2 and TAT were above cut-off values in 97, 66 and 89% of patients respectively. D-Di levels correlated with the extent of venous thrombosis whereas TAT and F 1 + 2 did not. Mean levels of D-Di decreased sharply during the first days of treatment but were still abnormal on day 10. A secondary increase of D-Di on days 6 or 10 by more than 3 μg/ml occurred in 4 of the 9 patients who developed a thromboembolic recurrence but in none of the 72 patients who had a more favorable outcome. F 1 + 2 and TAT time-courses were not related to clinical evolution. In the Enoxaparin group, there was no relationship between antifactor Xa activities and any biological markers. TAT and F 1 + 2 levels fell on day 2 and remained stable until day 10. In contrast, in the UH group, TAT and F 1 + 2 did not significantly decrease on day 2, probably due to a delay in dose adaptation, but they declined slowly until day 10.In conclusion, D-Di displays a higher sensitivity than F 1 + 2 or TAT for the diagnosis of D\T. D-Di, but not TAT or F 1 + 2, follow-up seems to be of potential value for early detection of recurrency. Hemostatic activation is controlled earlier by fixed doses of a low molecular weight heparin, irrespective of the plasma anti-factor Xa activities, than by unfractionated heparin at adapted doses.

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.

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