scholarly journals Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects

2012 ◽  
Vol 108 (9) ◽  
pp. 1652-1657 ◽  
Author(s):  
Elke Theuwissen ◽  
Ellen C. Cranenburg ◽  
Marjo H. Knapen ◽  
Elke J. Magdeleyns ◽  
Kirsten J. Teunissen ◽  
...  
Keyword(s):  
Vitamin K ◽  
Statistical Power ◽  
Thrombin Generation ◽  
Low Dose ◽  
Coagulation Factors ◽  
Peak Height ◽  
Matrix Gla Protein ◽  
High Dose ◽  
Age Related ◽  
Intervention Trials

Vitamin K is required for the carboxylation of Gla-proteins in the liver (coagulation factors) and extra-hepatic tissues, such as bone (osteocalcin, OC), and arterial wall (matrix Gla-protein, MGP). Although the coagulation factors are essentially fully carboxylated under normal conditions, 10–40 % of OC and MGP remains undercarboxylated. We were therefore interested to study the dose–response effects of extra intake of menaquinones on the carboxylation of the extra-hepatic Gla-proteins. A total of forty-two healthy Dutch men and women aged between 18 and 45 years were randomised into seven groups to receive: placebo capsules or menaquinone-7 (MK-7) capsules at a daily dose of 10, 20, 45, 90, 180 or 360 μg. Circulating uncarboxylated OC (ucOC), carboxylated OC (cOC) and desphospho-uncarboxylated MGP were measured by ELISA. The ucOC:cOC ratio was calculated from circulating ucOC and cOC values. Endogenous thrombin potential and peak height were determined by calibrated automated thrombography. To increase the statistical power, we collapsed the treatment groups into three dosage groups: placebo, low-dose supplementation (doses below RDA, Commission Directive 2008/100/EC), and high-dose supplementation (doses around RDA, Commission Directive 2008/100/EC). MK-7 supplementation at doses in the order of the RDA (Commission Directive 2008/100/EC) increased the carboxylation of circulating OC and MGP. No adverse effects on thrombin generation were observed. Extra MK-7 intake at nutritional doses around the RDA (Commission Directive 2008/100/EC) improved the carboxylation of the extra-hepatic vitamin K-dependent proteins. Whether this improvement contributes to public health, i.e. increasing the protection against age-related diseases needs further investigation in specifically designed intervention trials.

scholarly journals Intravenous Vitamin K1 for the Correction of Prolonged Prothrombin Times in Non-Bleeding Critically Ill Patients: A Prospective Observational Study

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2580
Author(s):  
Sofia Dahlberg ◽  
Ulf Schött ◽  
Emilia Ängeby Eriksson ◽  
Yllnor Tahirsylaj ◽  
Leon Schurgers ◽  
...  
Keyword(s):  
Critically Ill ◽  
Vitamin K ◽  
Critically Ill Patients ◽  
Thrombin Generation ◽  
Coagulation Factors ◽  
Matrix Gla Protein ◽  
Vitamin K1 ◽  
Clotting Factors ◽  
Short And Long Term ◽  
Intravenous Vitamin

The aim of this study was to evaluate the effects of vitamin K1 on various vitamin K-dependent proteins in critically ill patients with prolonged Owren PT. We included critically ill non-bleeding adult patients without liver failure or anticoagulation treatment, with Owren PT > 1.2, who were prescribed intravenous vitamin K1. Blood was drawn at baseline and at 20–28 h after vitamin K1 administration. At both time points, we measured various vitamin K-dependent proteins and coagulation assays. ClinicalTrials.gov; Identifier: NTC3782025. In total, 52 patients were included. Intravenous vitamin K1 reduced Owren PT, Quick PT, protein induced by vitamin K absence/antagonist-II and desphospho-uncarboxylated matrix Gla protein (dp-ucMGP), but not to normal levels. Concomitantly, there were increases in thrombin generation and the activity of coagulation factors II, VII, IX and X that was only counteracted with a small increase in Protein C activity. In conclusion, the results suggest that vitamin K1 strengthens coagulation as measured by PT decrease and increases in the activity of vitamin K-dependent clotting factors and thrombin generation. The decreased dp-ucMGP, and its potential positive short- and long-term non-coagulative effects, merits further research.

scholarly journals Experimental Model of Subclinical Vitamin K Deficiency

Folia Medica ◽  
2020 ◽  
Vol 62 (2) ◽  
pp. 378-384
Author(s):  
Silvia Gancheva ◽  
Martina Kitanova ◽  
Peter Ghenev ◽  
Maria Zhelyazkova-Savova
Keyword(s):  
Vascular Calcification ◽  
Vitamin K ◽  
Coagulation Factors ◽  
Matrix Gla Protein ◽  
Severe Bleeding ◽  
Dosing Schedule ◽  
K Deficiency ◽  
Calcium Deposits ◽  
Subclinical Vitamin ◽  
High Doses

Introduction: Vitamin K (VK) is a co-factor in the post-translational gamma glutamic carboxylation of Gla-proteins. VK-dependent coagulation factors are carboxylated in the liver by VK1. Osteocalcin and Matrix-Gla protein (MGP) are carboxylated in extrahepatic tissues by VK2. A model of VK deficiency would be suitable for studying extrahepatic Gla-proteins provided that severe bleeding is prevented. Aim: The aim of this work was to adapt an established protocol of vascular calcification by warfarin-induced inactivation of MGP as a calcification inhibitor, in an attempt to create a broader state of subclinical VK deficiency and to verify its safety. Materials and methods: Two consecutive experiments, each lasting 4 weeks, were required to modify the dosing schedule of warfa­rin and VK1 and to adapt it to the Wistar rats used. The original high doses of warfarin used initially had to be halved and the protective dose of VK1 to be doubled, in order to avoid treatment-induced hemorrhagic deaths. The second experiment aimed to confirm the efficacy and safety of the modified doses. To verify the VK deficiency, blood vessels were examined histologically for calcium deposits and serum osteocalcin levels were mea­sured. Results: The original dosing schedule induced VK deficiency, manifested by arterial calcifications and dramatic changes in carboxyl­ated and uncarboxylated osteocalcin. The modified dosing regimen caused similar vascular calcification and no bleeding. Conclusion: The modified protocol of carefully balanced warfarin and VK1 doses is an effective and safe way to induce subclinical VK deficiency that can be implemented to investigate VK-dependent proteins like osteocalcin.

scholarly journals Reduced Vitamin K Status as a Potentially Modifiable Risk Factor of Severe Coronavirus Disease 2019

2020 ◽  
Author(s):  
Anton S M Dofferhoff ◽  
Ianthe Piscaer ◽  
Leon J Schurgers ◽  
Margot P J Visser ◽  
Jody M W van den Ouweland ◽  
...  
Keyword(s):  
Vitamin K ◽  
Elastic Fiber ◽  
Protein S ◽  
Coagulation Factors ◽  
Matrix Gla Protein ◽  
Arterial Calcification ◽  
Fiber Damage ◽  
Fiber Degradation ◽  
Factor Ii ◽  
Poor Outcomes

Abstract Background Respiratory failure and thromboembolism are frequent in severe acute respiratory syndrome coronavirus 2–infected patients. Vitamin K activates both hepatic coagulation factors and extrahepatic endothelial anticoagulant protein S, required for thrombosis prevention. In times of vitamin K insufficiency, hepatic procoagulant factors are preferentially activated over extrahepatic proteins. Vitamin K also activates matrix Gla protein (MGP), which protects against pulmonary and vascular elastic fiber damage. We hypothesized that vitamin K may be implicated in coronavirus disease 2019 (COVID-19), linking pulmonary and thromboembolic disease. Methods A total of 135 hospitalized COVID-19 patients were compared with 184 historic controls. Inactive vitamin K–dependent MGP (desphospho-uncarboxylated [dp-uc] MGP) and prothrombin (PIVKA-II) were measured inversely related to extrahepatic and hepatic vitamin K status, respectively. Desmosine was measured to quantify the rate of elastic fiber degradation. Arterial calcification severity was assessed using computed tomography. Results dp-ucMGP was elevated in COVID-19 patients compared with controls (P < .001), with even higher dp-ucMGP in patients with poor outcomes (P < .001). PIVKA-II was normal in 82.1% of patients. dp-ucMGP was correlated with desmosine (P < .001) and with coronary artery (P = .002) and thoracic aortic (P < .001) calcification scores. Conclusions dp-ucMGP was severely increased in COVID-19 patients, indicating extrahepatic vitamin K insufficiency, which was related to poor outcome; hepatic procoagulant factor II remained unaffected. These data suggest pneumonia-induced extrahepatic vitamin K depletion leading to accelerated elastic fiber damage and thrombosis in severe COVID-19 due to impaired activation of MGP and endothelial protein S, respectively.

Abstract 345: Detection of Hypercoagulant Condition Caused by Elevated Prothrombin With a Thrombin Generation Assay

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
William C Chang ◽  
Kellie R Machlus ◽  
Alisa S Wolberg ◽  
Mikhail V Ovanesov
Keyword(s):  
Thrombin Generation ◽  
Point Of Care ◽  
Coagulation Factors ◽  
Peak Height ◽  
Additional Analysis ◽  
Substrate Consumption ◽  
Thrombin Generation Assay ◽  
Point Of Care Test ◽  
G20210a Mutation ◽  
Risk Patients

Hypercoagulability resulting from elevated prothrombin is associated with increased thrombosis risk. Patients with elevated prothrombin include those with the G20210A mutation that represents the 2nd most common risk factor for venous thrombosis in European Caucasians. We hypothesized that the commercial thrombin generation assay (TGA), which measures the rate of synthetic thrombin substrate consumption, may detect procoagulant condition caused by elevated prothrombin. Normal pooled plasma was treated with prothrombin or other coagulation factors to increase their levels to 200% or 400% of normal. TGA was performed using the Calibrated Automated Thrombogram (CAT) platform (Stago, USA) and analyzed with and without correction for substrate consumption. As expected, addition of elevated coagulation factors resulted in elevated TGA as measured by thrombin peak height (TPH) and endogenous thrombin potential (ETP). ETP allowed detection of up to 83% of spiked samples with 200% prothrombin but TPH has failed to distinguish these samples from the procoagulant samples obtained with other coagulation factors. For samples with 400% prothrombin, CAT failed to return values for TPH for 40% of samples and ETP for 100% of samples but the remaining 60% of TPH values were detected as the procoagulant samples. By analyzing the raw fluorescence data directly, we found that elevated prothrombin, but not other coagulation factors, resulted in thrombin substrate depletion which allowed us to correctly distinguish all samples within our dataset regarding whether or not they had added prothrombin. We conclude that the commercially available TGA has limited utility in distinguishing samples with elevated prothrombin but additional analysis of data can address this problem. With this additional analysis, TGA may be developable into new point-of-care test to diagnose patients with hypercoagulant conditions undetectable by currently used clotting assays. Disclaimer: This is an informal communication and represents authors’ best judgment. These comments do not bind or obligate FDA.

scholarly journals Issues in Interpreting Epidemiologic Studies of Populations Exposed to Low-Dose, High-Energy Photon Radiation

2020 ◽  
Vol 2020 (56) ◽  
pp. 176-187 ◽  
Author(s):  
Ethel S Gilbert ◽  
Mark P Little ◽  
Dale L Preston ◽  
Daniel O Stram
Keyword(s):  
Measurement Errors ◽  
Statistical Power ◽  
Low Dose ◽  
Risk Model ◽  
Atomic Bomb ◽  
Statistical Tests ◽  
High Energy ◽  
Epidemiologic Studies ◽  
Photon Radiation ◽  
High Dose

Abstract This article addresses issues relevant to interpreting findings from 26 epidemiologic studies of persons exposed to low-dose radiation. We review the extensive data from both epidemiologic studies of persons exposed at moderate or high doses and from radiobiology that together have firmly established radiation as carcinogenic. We then discuss the use of the linear relative risk model that has been used to describe data from both low- and moderate- or high-dose studies. We consider the effects of dose measurement errors; these can reduce statistical power and lead to underestimation of risks but are very unlikely to bring about a spurious dose response. We estimate statistical power for the low-dose studies under the assumption that true risks of radiation-related cancers are those expected from studies of Japanese atomic bomb survivors. Finally, we discuss the interpretation of confidence intervals and statistical tests and the applicability of the Bradford Hill principles for a causal relationship.

scholarly journals Characterizing Coagulation FVII from iPSC-Hepatocytes-like Cells: Setting the Basis for Cell Therapy Development

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 4-4
Author(s):  
Maria Eugenia Chollet ◽  
Elisabeth Andersen ◽  
Maria Eugenia de la Morena-Barrio ◽  
Carlos Bravo-Perez ◽  
Marie-Christine Mowinckel ◽  
...  
Keyword(s):  
Vitamin K ◽  
Thrombin Generation ◽  
Coagulation Factors ◽  
Activity Level ◽  
Primary Hepatocytes ◽  
Post Translational Modifications ◽  
Cellular Expression ◽  
Plasma Pool ◽  
Pngase F

Introduction To date studies on factor (F)VII and other hepatic vitamin K-dependent coagulation factors have relied on cell lines overexpressing these human genes. Even though these models have provided insight into the biology of these factors, they do not fully illustrate the in vivo situation. Thus, a relevant physiological model that mimics the in vivo processing of FVII in liver cells with potential for therapeutic use is needed. Methods Human induced pluripotent stem cells (hiPSCs) were differentiated into hepatocyte-like cells (iHLCs) using a non-transcription factor based, small molecule approach. Cells were grown in medium with vitamin K to ensure a correct gamma-carboxylation. Cellular FVII mRNA and protein were determined by RT-qPCR and proteomic and Western blot (WB), respectively. Secreted FVII antigen was measured by ELISA and WB and FVII activity was assessed by chromogenic assay and thrombin generation assay (TGA). Post-translational modifications of FVII protein (glycosylation) were studied using digestion with N-glycosylase F (PNGase F) and neuraminidase. Confocal immunofluorescence microscopy was used to assess the cellular expression of FVII and other vitamin K- dependent coagulation factors and inhibitors. Human primary hepatocytes or human plasma pool were used as a control in the assays. Results The resulting iHLCs expressed FVII mRNA in comparable levels to primary hepatocytes and cellular FVII peptides were identified by mass spectrometry studies. iHLCs secreted FVII at levels of around 70% compared to primary hepatocytes with detectable activity around 35% of the FVII activity level from primary hepatocytes. The TGA showed that cell medium from iHLCs when mixed with FVII deficient plasma was able to induce thrombin generation faster than the FVII depleted plasma alone (lagtime 3.2 vs 27.6 s, respectively). PNGase-F treatment showed that FVII secreted by iHLCs was N-glycosylated. Intracellular FVII was detected by WB as a band of approximately 63 kDa, slightly larger than FVII from plasma pool but similar to FVII from primary hepatocytes. Moreover, additional coagulation factors and inhibitors such as FII, FX, protein C and antithrombin were detected both at the mRNA and protein levels in the cells. Conclusions Stem cell-derived iHLCs produce and secrete FVII at physiologically relevant levels. The resulting FVII showed similar post-translational modifications to plasma FVII although some differences in proteolysis could be inferred. This iHLCs-derived FVII is able to initiate the extrinsic coagulation pathway. Our data support that these iHLCs can serve as a highly relevant model to study FVII and other vitamin K-dependent coagulation factors in vitro and constitute an important step towards the development of novel cell-based therapies for both FVII and other vitamin K-dependent coagulation factor deficiencies. Disclosures No relevant conflicts of interest to declare.

Vitamin K–containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3279-3283 ◽  
Author(s):  
Leon J. Schurgers ◽  
Kirsten J. F. Teunissen ◽  
Karly Hamulyák ◽  
Marjo H. J. Knapen ◽  
Hogne Vik ◽  
...  
Keyword(s):  
Vitamin K ◽  
Serum Vitamin ◽  
Life Time ◽  
Serum Levels ◽  
Coagulation Factors ◽  
Matrix Gla Protein ◽  
Vitamin K1 ◽  
Blood Coagulation Factors ◽  
Oral Anticoagulant Treatment ◽  
Over The Counter

Abstract Vitamin K is a cofactor in the production of blood coagulation factors (in the liver), osteocalcin (in bone), and matrix Gla protein (cartilage and vessel wall). Accumulating evidence suggests that for optimal bone and vascular health, relatively high intakes of vitamin K are required. The synthetic short-chain vitamin K1 is commonly used in food supplements, but recently the natural long-chain menaquinone-7 (MK-7) has also become available as an over-the-counter (OTC) supplement. The purpose of this paper was to compare in healthy volunteers the absorption and efficacy of K1 and MK-7. Serum vitamin K species were used as a marker for absorption and osteocalcin carboxylation as a marker for activity. Both K1 and MK-7 were absorbed well, with peak serum concentrations at 4 hours after intake. A major difference between the 2 vitamin K species is the very long half-life time of MK-7, resulting in much more stable serum levels, and accumulation of MK-7 to higher levels (7- to 8-fold) during prolonged intake. MK-7 induced more complete carboxylation of osteocalcin, and hematologists should be aware that preparations supplying 50 μg/d or more of MK-7 may interfere with oral anticoagulant treatment in a clinically relevant way.

Thrombin generation as an intermediate phenotype for venous thrombosis

2010 ◽  
Vol 103 (01) ◽  
pp. 114-122 ◽  
Author(s):  
Olivier Segers ◽  
René van Oerle ◽  
Hugo ten Cate ◽  
Jan Rosing ◽  
Elisabetta Castoldi
Keyword(s):  
Genetic Variation ◽  
Plasma Levels ◽  
Thrombin Generation ◽  
Activated Protein C ◽  
Coagulation Factors ◽  
Peak Height ◽  
Intermediate Phenotype ◽  
Nucleotide Polymorphisms ◽  
Thrombin Generation Assay

Summary In vitro thrombin generation, which reflects an individual’s plasma coagulation potential and has been shown to correlate with the risk of venous thromboembolism (VTE), might represent a useful intermediate phenotype for the genetic dissection of VTE. As a proof of principle, we have investigated whether the thrombin generation assay can detect changes in the haemostatic balance associated with common genetic variation affecting the level or function of coagulation factors and inhibitors. The study population consisted of 140 healthy individuals. Plasma levels of coagulation factors and inhibitors and thrombin generation parameters determined at low tissue factor (TF) ± thrombomodulin (TM) and at high TF ± activated protein C (APC) were available from a previous study. All individuals were genotyped for F5 Leiden, F2 G20210A and 19 additional single nucleotide polymorphisms (SNPs) in haemostasis-related genes. The association of each SNP with plasma levels of the corresponding proteins and with thrombin generation parameters (lag time, peak height and endogenous thrombin potential [ETP]) was evaluated by statistical analysis. Not only F5 Leiden and F2 G20210A, but also several other common SNPs, significantly affected thrombin generation parameters. In particular, FGA A1069G (Thr312Ala) decreased the ETP-APC, F2 A19911G increased the ETP-APC, F10 IVS2 C+517G decreased the ETP+APC, F12 C-46T decreased peak height at low TF, and TFPI T-287C and TFPI IVS7 T-33C decreased the ETP+APC. These results indicate that the thrombin generation assay is sensitive to genetic variation in haemostasis-related genes, which makes it a promising tool to identify novel genetic risk factors of VTE.

Efficacy of Prothrombin Complex Concentrate (PCC) for Reversal of Warfarin Effect.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 964-964
Author(s):  
Lorne Holland ◽  
Theodore Warkentin ◽  
Ravindra Sarode
Keyword(s):  
United States ◽  
Vitamin K ◽  
Dose Group ◽  
Low Dose ◽  
The United States ◽  
Factor Ix ◽  
Utilization Review ◽  
High Dose ◽  
Chi Square ◽  
Warfarin Reversal

Abstract In the United States supratherapeutic INRs are typically reversed with fresh frozen plasma (FFP). This requires transfusion of large volumes (10–15 ml/kg) with therapeutic delay, volume overload, risk for TRALI (transfusion related acute lung injury) and multiple donor exposures. Our Blood Utilization Review Committee recommends PCC as the preferred product for warfarin reversal. Profilnine (Alpha Therapeutic Corp, Los Angeles, CA) is PCC containing vitamin-K dependent clotting factors and dosed by FIX content. FII, VII and X content is no more than 150%, 35% and 100% of the FIX amount, respectively. The manufacturer’s suggested dose for warfarin reversal is 15–50 U/kg. The dose of PCC and need for vitamin K or FFP is determined by the clinician after consultation with the transfusion service. Sixty-five patients received PCC; 25 for reduction of INR prior to surgery or other interventions and 40 for treatment of a supratherapeutic INR (>5.0) with bleeding or risk of bleeding. Twenty-three patients with supratherapeutic INRs received low dose PCC (mean 25 U/kg) and 17 received high dose (mean 50 U/kg). The average admission INR was 9.0 (5.2–15.0) for the low-dose group and 8.6 (5.3–15) for the high-dose group. Repeat INR measurements occurred after PCC and again if FFP was transfused. Twenty patients had samples frozen for analysis of FII, VII, IX and X with a mean time between PCC infusion and sample draw of 2 hours (0.5–8.1). Ten of these were stable at the time of PCC infusion and were used to calculate relative factor recovery. The INR corrected (decreased to ≤3) in 55%(6/11) of cases following treatment with low-dose PCC, while high-dose PCC corrected the INR in 43%(3/7). Combination of PCC and FFP (mean 2 units, ~5–7 mL/kg) corrected the INR in 89% (16/18) and 87%(13/15) of cases for low and high-dose PCC, respectively. PCC dose, with or without FFP, had no effect on the likelihood of INR correction (Chi-square, p> 0.05). The addition of low dose FFP, however, significantly increased the response rate (Chi-square, p<0.05) for both doses. The average factor increment is summarized in Table 1. Differences in factor levels between the PCC and PCC plus FFP groups were not significant(ANOVA, p>0.05). Based on PCC dose the median recovery of factor IX was 100% with a median recovery for FII, VII and X of 168%, 32%, and 100% of the factor IX increment. When FFP was added to the treatment regimen the recovery of factor IX was 106% of the PCC dose. FII, VII, and X were 182%, 46%, and 119% of the FIX increment. Only FVII recovery was significantly higher in the PCC plus FFP group (Mann-Whitney, p< 0.05). In conclusion, treatment with Profilnine increases factor levels compatible with the manufacturer’s insert, but PCC plus FFP causes a larger FVII increment. Treatment with low or high dose PCC results in similar rates of INR correction. However, addition of FFP increases the rate of INR correction for both doses. Profilnine alone is, therefore, unable to reliably correct a supratherapeutic INR, and supplementation with small amounts of FFP is necessary to provide additional FVII. A PCC product with a higher content of FVII is a better therapeutic option but is not readily available in the United States. Factor increments following PCC infusion INR F II(%) F VII(%) F IX(%) F X(%) mean±SD PCC only Pre 8.3±4.5 11±10 7±7 10±10 6±3 Post 2.6±1.4 53±21 14±10 28±19 31±12 PCC plus FFP Pre 12.2±5.0 5±1 1±1 12±19 12±19 Post 1.9±0.8 76±28 20±12 45±22 53±19

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