Effect of Citrofortunella microcarpa (Calamansi) Peelings on Whole Blood Coagulation Using Blood Samples from Albino Mice

Citrofortunella microcarpa, locally known as calamansi in the Philippines, is an intergeneric hybrid between Citrus reticulata and Fortunella japonica. This fruit is widely cultivated in the Philippines for its fruit juice as an abundant source of vitamin C and as a condiment in many local foods in the country. Sadly, only the pulp is needed for squeezing while the peels are thrown after extracting the juice. Previous studies revealed that the peels of Citrus, as member of the Rutaceae family, can synthesize both coumarins and furanocoumarins wherein their derivates are used as oral anticoagulants which can inhibit vitamin K from functioning as a cofactor in the hepatic synthesis of the vitamin K-dependent coagulation factors II, VII, IX, and X. In this study, the extract of calamansi peelings were proven to have an anticoagulant property on blood samples from albino mice. This study will pave the way for scientists to allot time in studying calamansi peelings for it may be another source of medicine to help patients who are prone to have stroke, myocardial infarction, and other blood clotting diseases.

Download Full-text

Two Types of Prothrombin in Vitamin K Deficiency

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654194 ◽

1970 ◽

Vol 23 (03) ◽

pp. 633-637 ◽

Cited By ~ 21

Author(s):

H. C Hemker ◽

Annemarie D. Muller ◽

E. A Loeliger

Keyword(s):

Vitamin K ◽

Oral Anticoagulants ◽

Coagulation Factors ◽

The Other ◽

Vitamin K Deficiency ◽

Two Stage ◽

K Deficiency

SummaryIn vitamin K deficiency (either absolute or induced by oral anticoagulants) two types of prothrombin occur. One is not distinguishable from normal prothrombin. It generates thrombin quickly in a medium in which the factors V, VII and X, thromboplastin and Ca++ are present in sufficient amounts. The other is converted into thrombin much more slowly under the same conditions. In the onestage prothrombin assay only the first form is measured, in a two-stage prothrombin assay both forms are estimated. This accounts for the well-known discrepancy between these two tests in vitamin K deficiency. The abnormal prothrombin can be considered one of the Proteins Induced by Vitamin K Absence. The occurrence of this kind of proteins fits in the concept of the action of vitamin K as a co-factor in a system that converts polypeptide-precursors into coagulation factors.

Download Full-text

DEFECTS OF VITAMIN K-DEPENDENT FACTORS IN CA(11)-STABILI ZED STRUCTURE

10.1055/s-0038-1644320 ◽

1987 ◽

Author(s):

S R Poort ◽

C Krommenhoek-van Es ◽

I K van der Linden ◽

N H van Tilburg ◽

R M Bertina

Keyword(s):

Vitamin K ◽

Genetic Variants ◽

Protein C ◽

Conformational Transition ◽

Oral Anticoagulants ◽

Indirect Evidence ◽

Coagulation Factors ◽

Factor Ix ◽

Factor Vii ◽

Factor Ii

Vitamin K-dependent (anti)coagulation factors (factor II, VII, IX, X protein C and S) undergo a conformational transition upon binding of Ca(II), which is a prerequisite for their normal function. Abnormalities in these properties occur during vitamin K deficiency or treatment with anti vitamin K drugs and in some genetic variants of coagulation factors. Immunological assays utilizing antibodies against the Ca(II)-stabilized structure are useful to detect such abnormalities.Starting from specific rabbit antisera antibody populations specific for the Ca(II)-dependent conformation of factor II, VII, IX, X and protein C and S were isolated using immuno-affinity procedures. Subsequently immunoradiometric assays specific for the Ca(II)-dependent (Ca(II)Ag) and Ca(II)-independent (NonCa(II)Ag) conformations of the different proteins were developed. These assays were used for the analysis of plasmas of patients stably treated with oral anticoagulants; Ca(II)Ag, NonCa(II)Ag and their ratio were measured as function of the intensity of the treatment (INR 2.4 to 4.8). The same parameters were measured in plasmas of patients with hereditary coagulation disorders. After treatment with oral anticoagulation with an antivitamin K drug reduced ratios of Ca(II)Ag/-NonCa(II)Ag were observed for factor II, VII, IX, protein C and protein S. However, the actual degree of reduction and its dependence on the intensity of treatment varied for the different vitamin K-dependent proteins. In general Ca(II)Ag levels correspond nicely with the procoagulant activity of the concerning proteins. These data provide indirect evidence for the existence of abnormal (non and/or subcarboxylated) forms of the vitamin K-dependent proteins during oral anticoagulant treatment.Genetic variants with a mutation in one of the sites involved in the formation of the Ca(II)-s tab i1ized structure could be detected for factor IX, factor VII and factor II. However, the extent of reduction of the ratio Ca(II)Ag/-NonCa(II)Ag differed considerably in those variants.

Download Full-text

Abstract 164: Specific Point-of-Care Testing of Coagulation in Patients Treated With Non-Vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Stroke ◽

10.1161/str.47.suppl_1.164 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Florian Härtig ◽

Andreas Peter ◽

Charlotte Spencer ◽

Matthias Ebner ◽

Christine S Zürn ◽

...

Keyword(s):

Vitamin K ◽

Point Of Care ◽

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Rapid Assessment ◽

Plasma Concentrations ◽

Vitamin K Antagonist ◽

Point Of Care Testing ◽

Blood Samples ◽

First Time

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF) and venous thrombosis. Ischemic stroke rate in NOAC-treated AF-patients is 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT. Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity-POCT accurately predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban. Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment will be enrolled (N=40 for each NOAC). Subjects receiving other anticoagulants will be excluded. 6 blood samples will be collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations will be measured by mass spectrometry. Results (preliminary): Until now 138 blood samples of 23 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-371ng/mL. ECT-POCT ranged from 20-219s. Pearson’s correlation coefficient showed strong correlation for ECT-POCT and dabigatran-concentrations (r=0.94, p<0.001). Dabigatran-concentrations >50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT (>50s) with 100% sensitivity and 82% specificity. Baseline-samples not containing any dabigatran yielded normal ECT-POCT. Conclusions: This is the first study evaluating NOAC-specific POCT. Preliminary results show excellent correlation for ECT-POCT and dabigatran; relevant dabigatran-concentrations were detected in 100%. More pioneering results on NOAC-specific POCT will be presented.

Download Full-text

Problem-Based Review: Non Vitamin K Antagonist Oral Anticoagulants for the Acute Physician

Acute Medicine Journal ◽

10.52964/amja.0435 ◽

2015 ◽

Vol 14 (2) ◽

pp. 83-89

Author(s):

Jecko Thachil ◽

◽

James Gagg ◽

Keyword(s):

Vitamin K ◽

Oral Anticoagulants ◽

Factor Xa ◽

Coagulation Factors ◽

Rapid Onset ◽

Vitamin K Antagonist ◽

Thrombin Inhibitor ◽

Oral Formulations ◽

Direct Anticoagulants ◽

And Function

Non-vitamin K antagonist oral anticoagulants (NOACs), are direct anticoagulants which inhibit specific coagulation factors and function as anticoagulants. Three NOACs are currently licensed in the United Kingdom: dabigatran, a thrombin inhibitor, and rivaroxaban and apixaban, antagonists of factor Xa. They are set to change the anticoagulant landscape, which was previously ruled by warfarin and heparins. Their advantages including oral formulations, rapid onset and offset of action, predictable pharmacokinetics, no requirement for routine blood monitoring or dose adjustment and very few drug interactions. The increasing use of these drugs means the acute medicine physicians are likely to encounter patients who have been taking them. This article reviews some of the challenging clinical situations in which this may arise.

Download Full-text

Anticoagulation beyond direct thrombin and factor Xa inhibitors: indications for targeting the intrinsic pathway?

Thrombosis and Haemostasis ◽

10.1160/th12-11-0803 ◽

2013 ◽

Vol 110 (08) ◽

pp. 223-232 ◽

Cited By ~ 25

Author(s):

Maurits van Montfoort ◽

Joost Meijers

Keyword(s):

Vitamin K ◽

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Factor Xa ◽

Coagulation Factor ◽

Coagulation Factors ◽

Factor Xa Inhibitors ◽

Therapeutic Window ◽

Intrinsic Pathway ◽

Antithrombotic Drugs

SummaryAntithrombotic drugs like vitamin K antagonists and heparin have been the gold standard for the treatment and prevention of thromboembolic disease for many years. Unfortunately, there are several disadvantages of these antithrombotic drugs: they are accompanied by serious bleeding problems, it is necessary to monitor the therapeutic window, and there are various interactions with food and other drugs. This has led to the development of new oral anticoagulants, specifically inhibiting either thrombin or factor Xa. In terms of effectiveness, these drugs are comparable to the currently available anticoagulants; however, they are still associated with issues such as bleeding, reversal of the drug and complicated laboratory monitoring. Vitamin K antagonists, heparin, direct thrombin and factor Xa inhibitors have in common that they target key proteins of the haemostatic system. In an attempt to overcome these difficulties we investigated whether the intrinsic coagulation factors (VIII, IX, XI, XII, prekallikrein and high-molecular-weight kininogen) are superior targets for anticoagulation. We analysed epidemiological data concerning thrombosis and bleeding in patients deficient in one of the intrinsic pathway proteins. Furthermore, we discuss several thrombotic models in intrinsic coagulation factor-deficient animals. The combined results suggest that intrinsic coagulation factors could be suitable targets for anticoagulant drugs.

Download Full-text

Vitamin K antagonists in heart disease: Current status and perspectives (Section III)

Thrombosis and Haemostasis ◽

10.1160/th13-06-0443 ◽

2013 ◽

Vol 110 (12) ◽

pp. 1087-1107 ◽

Cited By ~ 251

Author(s):

Raffaele Caterina ◽

Steen Husted ◽

Lars Wallentin ◽

Felicita Andreotti ◽

Harald Arnesen ◽

...

Keyword(s):

Atrial Fibrillation ◽

Heart Disease ◽

Vitamin K ◽

Heart Valves ◽

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Coagulation Factors ◽

Current Status ◽

Cardiovascular Therapy ◽

Specific Disorders

SummaryOral anticoagulants are a mainstay of cardiovascular therapy, and for over 60 years vitamin K antagonists (VKAs) were the only available agents for long-term use. VKAs interfere with the cyclic inter-conversion of vitamin K and its 2,3 epoxide, thus inhibiting γ-carboxylation of glutamate residues at the amino-termini of vitamin K-dependent proteins, including the coagulation factors (F) II (prothrombin), VII, IX and X, as well as of the anticoagulant proteins C, S and Z. The overall effect of such interference is a dose-dependent anticoagulant effect, which has been therapeutically exploited in heart disease since the early 1950s. In this position paper, we review the mechanisms of action, pharmacological properties and side effects of VKAs, which are used in the management of cardiovascular diseases, including coronary heart disease (where their use is limited), stroke prevention in atrial fibrillation, heart valves and/or chronic heart failure. Using an evidence-based approach, we describe the results of completed clinical trials, highlight areas of uncertainty, and recommend therapeutic options for specific disorders. Although VKAs are being increasingly replaced in most patients with non-valvular atrial fibrillation by the new oral anticoagulants, which target either thrombin or FXa, the VKAs remain the agents of choice for patients with atrial fibrillation in the setting of rheumatic valvular disease and for those with mechanical heart valves.

Download Full-text

Abstract 20: Specific Point-of-care Testing of Coagulation in Patients Treated with Non-vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Stroke ◽

10.1161/str.48.suppl_1.20 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Florian J Härtig ◽

Andreas Peter ◽

Charlotte Spencer ◽

Matthias Ebner ◽

Christine Meyer-Zuern ◽

...

Keyword(s):

Vitamin K ◽

Whole Blood ◽

Point Of Care ◽

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Rapid Assessment ◽

Plasma Concentrations ◽

Vitamin K Antagonist ◽

Point Of Care Testing ◽

Blood Samples

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF). Despite treatment, stroke rate in NOAC-treated AF-patients remains 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis or reversal therapy, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT. Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity (ENOX)-POCT predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban. Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment are enrolled in the SPOCT-NOAC I trial (N=40 for each NOAC). Subjects receiving other anticoagulants are excluded. Six blood samples are collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations are measured by mass spectrometry. Results: 240 blood samples of 40 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-274ng/mL. ECT-POCT ranged from 20-196s. Pearson’s correlation coefficient showed strong correlation between ECT-POCT and dabigatran-concentrations (r=0.87). Performance was improved through the use of citrated in place of non-citrated whole blood (r=0.93). Dabigatran-concentrations >50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT >50s with 98% sensitivity and 79% specificity. Baseline-samples not containing any dabigatran yielded normal ECT values. Conclusions: This is the first study evaluating NOAC-specific POCT. Final results in the dabigatran group of SPOCT-NOAC show excellent correlation between ECT-POCT and dabigatran plasma concentrations; performance of ECT-POCT is even increased through the use of citrated whole blood. Relevant dabigatran-concentrations are detected with excellent sensitivity and specificity. In addition to ECT-POCT, we will present data on ENOX-POCT from apixaban-, edoxaban- and rivaroxaban-treated patients.

Download Full-text

Clinical Applications of 4-Factor Prothrombin Complex Concentrate: A Practical Pathologist's Perspective

Archives of Pathology & Laboratory Medicine ◽

10.5858/arpa.2014-0366-rs ◽

2014 ◽

Vol 139 (12) ◽

pp. 1568-1575 ◽

Cited By ~ 7

Author(s):

David Unold ◽

Christopher A. Tormey

Keyword(s):

Vitamin K ◽

Prothrombin Complex Concentrate ◽

Oral Anticoagulants ◽

Coagulation Factors ◽

The United States ◽

Vitamin K Antagonist ◽

Reversal Agents ◽

Therapeutic Doses ◽

Potential Use

A 4-factor prothrombin complex concentrate (4F-PCC), containing therapeutic doses of vitamin K–dependent coagulation factors, was recently licensed in the United States for reversal of vitamin K antagonist therapy. However, given the emergence of several oral anticoagulants for which there are no specific reversal agents, and the existence of many other complex bleeding disorders, it is likely that clinicians will seek to use 4F-PCCs for any number of off-label indications. Thus, the goal of this review is to explore practical issues regarding 4F-PCC, with an emphasis on issues relevant to blood bankers and pathologists. Specifically, our aims are to (1) examine the role of 4F-PCC in vitamin K antagonist reversal, (2) review its potential use in the treatment of hemorrhage due to novel oral anticoagulants, and (3) explore potential uses in liver disease, trauma-associated bleeding, and rare coagulopathies. Safety and other practical considerations of 4F-PCCs will also be discussed.

Download Full-text

Vitamin K: The coagulation vitamin that became omnipotent

Thrombosis and Haemostasis ◽

10.1160/th07-04-0266 ◽

2007 ◽

Vol 98 (07) ◽

pp. 120-125 ◽

Cited By ~ 143

Author(s):

Ellen Cranenburg ◽

Leon Schurgers ◽

Cees Vermeer

Keyword(s):

Side Effects ◽

Vitamin K ◽

Oral Anticoagulants ◽

Coagulation Factors ◽

Matrix Gla Protein ◽

Specific Gene ◽

Healthy Individuals ◽

Oral Anticoagulant Treatment ◽

Increased Risk ◽

Effect Of Treatment

SummaryVitamin K, discovered in the 1930s, functions as cofactor for the post-translational carboxylation of glutamate residues. Gammacarboxy glutamic acid (Gla)-residues were first identified in prothrombin and coagulation factors in the 1970s; subsequently, extra-hepatic Gla proteins were described,including osteocalcin and matrix Gla protein (MGP). Impairment of the function of osteocalcin and MGP due to incomplete carboxylation results in an increased risk for developing osteoporosis and vascular calcification, respectively, and is an unexpected side effect of treatment with oral anticoagulants. It is conceivable that other side effects, possible involving growth-arrest-specific gene 6 (Gas6) protein will be identified in forthcoming years. In healthy individuals, substantial fractions of osteocalcin and MGP circulate as incompletely carboxylated species, indicating that the majority of these individuals is subclinically vitamin K-deficient. Potential new application areas for vitamin K are therefore its use in dietary supplements and functional foods for healthy individuals to prevent bone and vascular disease, as well as for patients on oral anticoagulant treatment to offer them protection against coumarin-induced side effects and to reduce diet-induced fluctuations in their INR values.

Download Full-text

Factor XI as a Target for New Anticoagulants

Hämostaseologie ◽

10.1055/a-1384-3715 ◽

2021 ◽

Vol 41 (02) ◽

pp. 104-110

Author(s):

James C. Fredenburgh ◽

Jeffrey I. Weitz

Keyword(s):

Vitamin K ◽

Animal Studies ◽

Vitamin K Antagonists ◽

Oral Anticoagulants ◽

Direct Oral Anticoagulants ◽

Factor Xa ◽

Coagulation Factors ◽

Clotting Factors ◽

Factor Xi ◽

Factor Xi Deficiency

AbstractDespite advances in anticoagulant therapy, thrombosis remains the leading cause of morbidity and mortality worldwide. Heparin and vitamin K antagonists (VKAs), the first anticoagulants to be used successfully for the prevention and treatment of thrombosis, are associated with a risk of bleeding. These agents target multiple coagulation factors. Thus, by activating antithrombin, heparin mainly inhibits factor Xa and thrombin, whereas VKAs lower the levels of the vitamin K–dependent clotting factors. Direct oral anticoagulants, which have replaced VKAs for many indications, inhibit only factor Xa or thrombin. Although the direct oral anticoagulants are associated with less bleeding than VKAs, bleeding remains their major side effect. Epidemiological and animal studies have identified factor XI as a target for potentially safer anticoagulant drugs because factor XI deficiency or inhibition protects against thrombosis and is associated with little or no bleeding. Several factor XI–directed strategies are currently under investigation. This article (1) reviews the rationale for the development of factor XI inhibitors, (2) identifies the agents in most advanced stages of development, (3) describes the results of completed clinical trials and provides a summary of those underway, and (4) highlights the opportunities and challenges for this next generation of anticoagulants.

Download Full-text