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1.  Major Haemorrhage during Vitamin K Antagonist Treatment: The Influence of Thyroid Hormone Levels 
European Thyroid Journal  2014;3(1):32-37.
Annually, approximately 1-3% of patients treated with vitamin K antagonists (VKA) suffer from major haemorrhage. Since high levels of free thyroxine (fT4) are associated with increased thrombosis risk, the aim was to assess whether low levels of fT4 contribute to major haemorrhage in patients under VKA treatment.
The FACTORS (Factors in Oral Anticoagulant Safety) study is a case-control study on patients receiving VKA treatment, including 110 cases with major haemorrhage. Controls were 220 matched participants treated with VKA without major haemorrhage. Odds ratios (OR) and 95% confidence intervals (95% CI) for the association of fT4 levels with major haemorrhage were calculated for different fT4 cutoffs by conditional logistic regression.
In patients with an fT4 level below 13 pmol/l, the risk of major haemorrhage was 5-fold increased (OR = 5.1; 95% CI: 0.9-28.6) compared with patients with an fT4 level above 13 pmol/l. At a cutoff of 14 pmol/l, the risk was 3-fold increased (OR = 2.9; 95% CI: 1.0-8.5). High levels of fT4 did not affect bleeding risk. No clear effect of thyroid-stimulating hormone and thyroid peroxidase antibodies was seen on the risk of major haemorrhage.
These results indicate that fT4 levels below 14 pmol/l play a role in the aetiology of major haemorrhage in VKA users.
PMCID: PMC4005261  PMID: 24847463
Free thyroxine; Vitamin K antagonists; Coagulation; Haemorrhage; Epidemiology

2.  Single Nucleotide Variants in the Protein C Pathway and Mortality in Dialysis Patients 
PLoS ONE  2014;9(5):e97251.
The protein C pathway plays an important role in the maintenance of endothelial barrier function and in the inflammatory and coagulant processes that are characteristic of patients on dialysis. We investigated whether common single nucleotide variants (SNV) in genes encoding protein C pathway components were associated with all-cause 5 years mortality risk in dialysis patients.
Single nucleotides variants in the factor V gene (F5 rs6025; factor V Leiden), the thrombomodulin gene (THBD rs1042580), the protein C gene (PROC rs1799808 and 1799809) and the endothelial protein C receptor gene (PROCR rs867186, rs2069951, and rs2069952) were genotyped in 1070 dialysis patients from the NEtherlands COoperative Study on the Adequacy of Dialysis (NECOSAD) cohort) and in 1243 dialysis patients from the German 4D cohort.
Factor V Leiden was associated with a 1.5-fold (95% CI 1.1–1.9) increased 5-year all-cause mortality risk and carriers of the AG/GG genotypes of the PROC rs1799809 had a 1.2-fold (95% CI 1.0–1.4) increased 5-year all-cause mortality risk. The other SNVs in THBD, PROC, and PROCR were not associated with 5-years mortality.
Our study suggests that factor V Leiden and PROC rs1799809 contributes to an increased mortality risk in dialysis patients.
PMCID: PMC4016291  PMID: 24816905
3.  Differential Action of the Bisphosphonates (3-Amino-1-Hydroxypropylidene)-1,1-Bisphosphonate (APD) and Disodium Dichloromethylidene Bisphosphonate (Cl2MDP) on Rat Macrophage-mediated Bone Resorption In Vitro 
Journal of Clinical Investigation  1982;70(5):927-933.
The bisphosphonates (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) and disodium dichloromethylidene bisphosphonate (Cl2MDP) effectively inhibit the accelerated bone resorption associated with some skeletal disorders, e.g., Paget's disease. However, it has not been established whether these compounds exert their inhibitory effect by rendering the bone mineral more resistant to degradation, by diminishing the activity of resorbing cells, or through some combination of both activities. In this study, we have tested these possibilities using an in vitro resorption assay system consisting of elicited rat peritoneal macrophages co-cultured with particles of 45Ca-labeled, devitalized rat bone. This assay system permits the quantitative assessment of the action of APD and Cl2MDP on the two major phases of bone resorption (cell-substrate attachment and osteolysis) under circumstances where the drugs are present continuously or, most importantly for the issues in question, after the separate pretreatment of the particles or the resorbing cells.
Our data indicate that (a) Both APD and Cl2MDP at concentrations ≥5 × 10-6 M diminish macrophage-mediated 45Ca release (i.e., bone resorption) in a log dose-dependent fashion. (b) A 10-min pretreatment of bone particles with either bisphosphonate (P-C-P) similarly inhibits resorptive activity, but is most pronounced with Cl2MDP. However, only APD is effective in reducing resorption when cells are preincubated (for 24 h) with P-C-P. (c) In cultures containing both labeled and unlabeled bone, significant inhibition occurs only when the labeled particles are coated with P-C-P (indicating that the action of P-C-P-treated bone is highly localized). (d) P-C-P does not diminish cell-bone particle attachment, an essential step in the resorptive process. On the other hand, delaying the addition of P-C-P until after cell-bone attachment is completed significantly reduces the resorption-inhibiting effect of these compounds. (e) Cl2MDP reduces culture DNA content in proportion to its inhibitory effect on resorption, and both the inhibitory and cytotoxic actions of this P-C-P are dependent upon the presence of bone. On the other hand, APD is cytotoxic only at very high concentrations (10-4 M), acts independently of the presence of bone, and inhibits resorption without killing cells.
We conclude that the mechanisms of action of APD and Cl2MDP are markedly different. Cl2MDP is a potent cytotoxin in the presence of bone and apparently exerts its inhibitory effect in this manner. APD is noncytotoxic at levels adequate to suppress resorption and, therefore, must inhibit macrophage activity by some other mechanism. Neither P-C-P appears to limit resorption by decreasing the solubility of mineralized bone matrix.
PMCID: PMC370305  PMID: 7130396
6.  Regulation of the F11, Klkb1, Cyp4v3 Gene Cluster in Livers of Metabolically Challenged Mice 
PLoS ONE  2013;8(9):e74637.
Single nucleotide polymorphisms (SNPs) in a 4q35.2 locus that harbors the coagulation factor XI (F11), prekallikrein (KLKB1), and a cytochrome P450 family member (CYP4V2) genes are associated with deep venous thrombosis (DVT). These SNPs exert their effect on DVT by modifying the circulating levels of FXI. However, SNPs associated with DVT were not necessarily all in F11, but also in KLKB1 and CYP4V2. Here, we searched for evidence for common regulatory elements within the 4q35.2 locus, outside the F11 gene, that might control FXI plasma levels and/or DVT risk. To this end, we investigated the regulation of the orthologous mouse gene cluster under several metabolic conditions that impact mouse hepatic F11 transcription. In livers of mice in which HNF4α, a key transcription factor controlling F11, was ablated, or reduced by siRNA, a strong decrease in hepatic F11 transcript levels was observed that correlated with Cyp4v3 (mouse orthologue of CYP4V2), but not by Klkb1 levels. Estrogens induced hepatic F11 and Cyp4v3, but not Klkb1 transcript levels, whereas thyroid hormone strongly induced hepatic F11 transcript levels, and reduced Cyp4v3, leaving Klkb1 levels unaffected. Mice fed a high-fat diet also had elevated F11 transcription, markedly paralleled by an induction of Klkb1 and Cyp4v3 expression. We conclude that within the mouse F11, Klkb1, Cyp4v3 gene cluster, F11 and Cyp4v3 frequently display striking parallel transcriptional responses suggesting the presence of shared regulatory elements.
PMCID: PMC3774739  PMID: 24066149
7.  Protease-Activated Receptor (PAR)2, but Not PAR1, Is Involved in Collateral Formation and Anti-Inflammatory Monocyte Polarization in a Mouse Hind Limb Ischemia Model 
PLoS ONE  2013;8(4):e61923.
In collateral development (i.e. arteriogenesis), mononuclear cells are important and exist as a heterogeneous population consisting of pro-inflammatory and anti-inflammatory/repair-associated cells. Protease-activated receptor (PAR)1 and PAR2 are G-protein-coupled receptors that are both expressed by mononuclear cells and are involved in pro-inflammatory reactions, while PAR2 also plays a role in repair-associated responses. Here, we investigated the physiological role of PAR1 and PAR2 in arteriogenesis in a murine hind limb ischemia model.
Methods and Results
PAR1-deficient (PAR1-/-), PAR2-deficient (PAR2-/-) and wild-type (WT) mice underwent femoral artery ligation. Laser Doppler measurements revealed reduced post-ischemic blood flow recovery in PAR2-/- hind limbs when compared to WT, while PAR1-/- mice were not affected. Upon ischemia, reduced numbers of smooth muscle actin (SMA)-positive collaterals and CD31-positive capillaries were found in PAR2-/- mice when compared to WT mice, whereas these parameters in PAR1-/- mice did not differ from WT mice. The pool of circulating repair-associated (Ly6C-low) monocytes and the number of repair-associated (CD206-positive) macrophages surrounding collaterals in the hind limbs were increased in WT and PAR1-/- mice, but unaffected in PAR2-/- mice. The number of repair-associated macrophages in PAR2-/- hind limbs correlated with CD11b- and CD115-expression on the circulating monocytes in these animals, suggesting that monocyte extravasation and M-CSF-dependent differentiation into repair-associated cells are hampered.
PAR2, but not PAR1, is involved in arteriogenesis and promotes the repair-associated response in ischemic tissues. Therefore, PAR2 potentially forms a new pro-arteriogenic target in coronary artery disease (CAD) patients.
PMCID: PMC3630144  PMID: 23637930
8.  Modulation of Mouse Coagulation Gene Transcription following Acute In Vivo Delivery of Synthetic Small Interfering RNAs Targeting HNF4α and C/EBPα 
PLoS ONE  2012;7(6):e38104.
Hepatocyte nuclear factor 4α (HNF4α) and CCAAT/enhancer-binding protein α (C/EBPα) are important for the transcriptional control of coagulation factors. To determine in vivo the direct role of HNF4α and C/EBPα in control of genes encoding coagulation factors, a synthetic small interfering (si)RNA approach was used that enabled strong reduction of mouse hepatic HNF4α and C/EBPα under conditions that minimized target-related secondary effects. For both HNF4α and C/EBPα, intravenous injection of specific synthetic siRNAs (siHNF4α and siC/EBPα) resulted in more than 75% reduction in their liver transcript and protein levels 2 days post-injection. For siHNF4α, this coincided with marked and significantly reduced transcript levels of the coagulation genes Hrg, Proz, Serpina5, F11, F12, F13b, Serpinf2, F5, and F9 (in order of magnitude of effect) as compared to levels in control siRNA injected animals. Significant decreases in HNF4α target gene mRNA levels were also observed at 5 days post-siRNA injection, despite a limited level of HNF4α knockdown at this time point. Compared to HNF4α, C/EBPα knockdown had a modest impact on genes encoding coagulation factors. A strong reduction in C/EBPα transcript and protein levels resulted in significantly affected transcript levels of the control genes Pck1 and Fasn and a modest downregulation for coagulation genes Fba, Fbg and F5. F5 and F11 were the sole coagulation genes that were significantly affected upon prolonged (5 day) C/EBPα knockdown. We conclude that in the mouse, HNF4α has a direct and essential regulatory role for multiple hepatic coagulation genes, while a role for C/EBPα is more restricted. In addition, this study demonstrates that synthetic siRNA provides a simple and fast means for determining liver transcription factor involvement in vivo.
PMCID: PMC3365905  PMID: 22675511
9.  Gross deletions/duplications in PROS1 are relatively common in point mutation-negative hereditary protein S deficiency 
Human Genetics  2009;126(3):449-456.
Hereditary protein S (PS) deficiency is an autosomal disorder caused by mutations in the PS gene (PROS1). Conventional PCR-based mutation detection identifies PROS1 point mutations in approximately 50% of the cases. To verify if gross copy number variations (CNVs) are often present in point mutation-negative hereditary PS deficiency we used multiplex ligation-dependent probe amplification (MLPA) as a detection tool in samples from individuals with a high probability of having true PS deficiency. To this end, DNA samples from nine PS deficient probands with family members (seven type I and two type III) and nine isolated probands (three type I and six type III), in whom PROS1 mutations were not found by DNA sequencing, were evaluated. An independent quantitative PCR (qPCR) was performed to confirm the findings of the MLPA assay. Family members were also tested when DNA was available. Gross abnormalities of PROS1 were found in six out of eighteen probands. In three probands complete deletion of the gene was detected. Two probands had a partial deletion involving different parts of the gene (one from exon 4 through 9 and another from exon 9 through 11). One family showed a duplication of part of PROS1. qPCR analysis was in accordance with these results. In conclusion, this study substantiates that gross gene abnormalities in PROS1 are relatively common in hereditary PS deficient patients and that MLPA is a useful tool for direct screening of CNVs in PROS1 point mutation-negative individuals.
PMCID: PMC3774415  PMID: 19466456
10.  Differential Gene Expression Changes in Children with Severe Dengue Virus Infections 
The host response to dengue virus infection is characterized by the production of numerous cytokines, but the overall picture appears to be complex. It has been suggested that a balance may be involved between protective and pathologic immune responses. This study aimed to define differential immune responses in association with clinical outcomes by gene expression profiling of a selected panel of inflammatory genes in whole blood samples from children with severe dengue infections.
Methodology/Principal Findings
Whole blood mRNA from 56 Indonesian children with severe dengue virus infections was analyzed during early admission and at day −1, 0, 1, and 5–8 after defervescence. Levels were related to baseline levels collected at a 1-month follow-up visit. Processing of mRNA was performed in a single reaction by multiplex ligation-dependent probe amplification, measuring mRNA levels from genes encoding 36 inflammatory proteins and 14 Toll-like receptor (TLR)-associated molecules. The inflammatory gene profiles showed up-regulation during infection of eight genes, including IFNG and IL12A, which indicated an antiviral response. On the contrary, genes associated with the nuclear factor (NF)-κB pathway were down-regulated, including NFKB1, NFKB2, TNFR1, IL1B, IL8, and TNFA. Many of these NF-κB pathway–related genes, but not IFNG or IL12A, correlated with adverse clinical events such as development of pleural effusion and hemorrhagic manifestations. The TLR profile showed that TLRs were differentially activated during severe dengue infections: increased expression of TLR7 and TLR4R3 was found together with a decreased expression of TLR1, TLR2, TLR4R4, and TLR4 co-factor CD14.
These data show that different immunological pathways are differently expressed and associated with different clinical outcomes in children with severe dengue infections.
Author Summary
Dengue virus infection is an impressively emerging disease that can be fatal in severe cases. It is not precisely clear why some patients progress to severe disease whereas most patients only suffer from a mild infection. In severe disease, a “cytokine storm” is induced, which indicates the release of a great number of inflammatory mediators (“cytokines”). Evidence suggested that a balance could be involved between protective and pathologic cytokine release patterns. We studied this concept in a cohort of Indonesian children with severe dengue disease using a gene expression profiling method.
The study showed that the immune response to severe dengue infection was characterized by up-regulation of interferon pathway–associated cytokines and down-regulation of nuclear factor (NF)-kappaB pathway–associated cytokines. Many of the NF-kappaB pathway–related genes, but not the interferon pathway–associated genes, correlated with adverse clinical events such as development of pleural effusion and hemorrhagic manifestations. In addition, the study showed that the expression of specific pathogen recognition receptors called Toll-like receptors was differentially regulated in patients with dengue. Together, the data show that different immunological pathways may indeed be differently expressed and associated with different clinical outcomes in children with severe dengue infections.
PMCID: PMC2274954  PMID: 18398488
11.  Inflammatory Cytokines as Risk Factors for a First Venous Thrombosis: A Prospective Population-Based Study 
PLoS Medicine  2006;3(8):e334.
In case-control studies, elevated levels of interleukins 6 and 8 have been found to be associated with an increased risk of venous thrombosis (VT). Because of the design of these studies, it remained uncertain whether these alterations were a cause or a result of the VT. In order to distinguish between the two, we set out to measure the levels of six inflammatory markers prior to thrombosis in a population-based cohort using a nested case-cohort design.
Methods and Findings
Between August 1995 and June 1997, blood was collected from 66,140 people in the second Norwegian Health Study of Nord-Trøndelag (HUNT2). We identified venous thrombotic events occurring between entry and 1 January 2002. By this date we had registered 506 cases with a first VT; an age- and sex-stratified random sample of 1,464 controls without previous VT was drawn from the original cohort. Levels of interleukins 1β, 6, 8, 10, 12p70, and tumour necrosis factor-α were measured in the baseline sample that was taken 2 d to 75 mo before the event (median 33 mo). Cut-off points for levels were the 80th, 90th, and 95th percentile in the control group. With odds ratios ranging from 0.9 (95% CI: 0.6–1.5) to 1.1 (95% CI: 0.7–1.8), we did not find evidence for a relationship between VT and an altered inflammatory profile.
The results from this population sample show that an altered inflammatory profile is more likely to be a result rather than a cause of VT, although short-term effects of transiently elevated levels cannot be ruled out.
An altered inflammatory profile appears more likely to be a result than a cause of venous thrombosis.
Editors' Summary
Blood clots (thromboses) are a common medical problem, especially in people who have been immobilized for a variety of reasons, who have other medical or surgical conditions, or who take certain types of drugs such as oral contraceptives. As well as these factors, various genetic changes make it more likely that certain people will develop a thrombosis. The most well known of these genetic changes is in a clotting factor, Factor V. Instead of the normal clotting factor V, some people have a variant known as Factor V Leiden, which makes them more likely to develop a thrombosis. (It is so named as it was discovered by researchers in Leiden, Netherlands.) Researchers are trying to find out if other abnormalities, particularly in levels of substances involved in inflammation, might make the chance of thrombosis more common. Identifying such changes might make it easier to predict who might be at risk of getting a thrombosis—for example, when a patient has to have an operation—and thus give them appropriate preventative measures.
Why Was This Study Done?
Previous studies have shown that the levels of inflammatory substances, known as cytokines, are raised around the time of a thrombosis. However, because of the design of these studies it was not clear whether these alterations were a cause or a result of the thrombosis. These researchers wanted to measure the levels of six cytokines before thrombosis in a large group of people and follow them to see if any particular level of cytokine made it more likely that they would go on to develop a thrombosis.
What Did the Researchers Do and Find?
During a three-year period between August 1995 and June 1997, blood was collected from 66,140 people in the second Norwegian Health Study of Nord-Trøndelag (HUNT2). Anyone who had a thrombosis between the start of the study and the beginning of 2002 was identified—506 people in all. Blood samples, taken from these people (cases) between two days and 75 months before the thrombosis happened, were used to measure levels of a number of different cytokines (abbreviated to IL-1β, IL-6, IL-8, IL-10, IL12p70, and tumour necrosis factor alpha [TNF-α]). These levels were then compared with those in samples also taken earlier from 1,464 people who were similar to the cases but had no thrombosis (controls). The authors found no evidence for a relationship between the chance of getting a thrombosis and a change in any of these markers of inflammation.
What Do These Findings Mean?
It seems unlikely that any long-term changes in levels of cytokines make any difference as to whether or not people develop a thrombosis. Hence, any changes seen in previous studies are most likely to have been the result of the thrombosis. However, the researchers could not rule out that changes occurred in the hours or days immediately before the thrombosis, although that seems unlikely. In any case, the levels of these cytokines do not seem to be useful as a clinical tool to predict who is at risk of thrombosis.
Additional Information.
Please access these Web sites via the online version of this summary at
MedlinePlus encyclopedia entries on deep venous thrombosis and pulmonary embolus
Omni, a health information service in the UK run by the Resource Discovery Network, has links to pages of information on venous thrombosis
The HUNT studies are described in this Web site
PMCID: PMC1551920  PMID: 16933968
12.  Authors' Reply 
PLoS Medicine  2006;3(4):e210.
PMCID: PMC1455474
13.  A C1173T Dimorphism in the VKORC1 Gene Determines Coumarin Sensitivity and Bleeding Risk 
PLoS Medicine  2005;2(10):e312.
A C1173T polymorphism in intron 1 of the VKORC1 gene has been claimed to determine the interindividual variability in the response to vitamin K antagonist therapy (VKA), but it is unknown whether it also influences bleeding risk. We aimed to confirm the relationship between C1173T status and phenprocoumon or acenocoumarol use, and to examine the risk of severe bleeding for the various genotypes.
Methods and Findings
We studied this in a case-control study of 110 patients who bled during VKA therapy and 220 control patients free of bleeding under the same therapy. To achieve the same target INR, CT genotype and TT genotype control patients required less phenprocoumon (CC genotype 2.9 mg/d [95% confidence interval (CI): 2.6–3.2], CT genotype 2.6 mg/d [95% CI: 2.1–3.1], TT genotype 1.4 mg/d [95 % CI: 1.1–1.7]) or acenocoumarol (CC genotype 3.2 mg/d [95% CI: 2.9–3.5], CT genotype 2.3 mg/d [95% CI: 2.1–2.5], TT genotype 1.7 mg/d [95% CI: 1.3–2.1]) than CC genotype control patients. Compared with CC genotype individuals, carriers of at least one T allele had an increased risk of bleeding in the phenprocoumon users (crude odds ratio = 2.6, 95% CI: 1.2–5.7), but not in acenocoumarol users (crude odds ratio = 1.2, 95% CI: 0.6–2.3).
These findings encourage taking further steps towards the evaluation of the use of VKORC1 genetic testing for bleeding prevention in individuals who receive VKA therapy.
A polymorphism in the VKORC1 gene may affect the dose of vitamin K antagonists needed and the risk of bleeding after anticoagulation in some patients.
PMCID: PMC1251635  PMID: 16201835
14.  Analysis of blood coagulation in mice: pre-analytical conditions and evaluation of a home-made assay for thrombin-antithrombin complexes 
Thrombosis Journal  2005;3:12.
The use of mouse models for the study of thrombotic disorders has gained increasing importance. Methods for measurement of coagulation activation in mice are, however, scarce. The primary aim of this study was to develop a specific mouse thrombin-antithrombin (TAT) ELISA for measurement of coagulation activation and to compare it with two commercially available assays for human TAT complexes. In addition, we aimed to improve methods for mouse plasma anticoagulation and preparation.
Methods and results
First, for the measurement of TAT-complexes in plasma a mouse specific TAT-ELISA was developed using rabbit polyclonal antibodies raised against mouse thrombin and rat antithrombin, respectively. This ELISA detected an increase in TAT levels in a mouse model of endotoxemia. Two commercial human TAT ELISAs appeared to be less specific for mouse thrombin-rat antithrombin complexes.
Second, to prevent clotting of mouse blood sodium citrate was either mixed with blood during collection in a syringe or was injected intravenously immediately prior to blood collection. Intravenous sodium citrate completely inhibited blood coagulation resulting in plasma with consistently low TAT levels. Sodium citrate mixed with blood during collection resulted in increased TAT levels in 4 out of 16 plasma samples. Third, heparinase was added to plasma samples after in vivo injection of different heparin doses to test its neutralizing effect. Heparinase neutralized up to a 20 U of heparin/mouse and resulted in accurate APTT and factor VIII determinations.
These procedures and reagents for plasma preparation and coagulation testing will improve studies on thrombotic disorders in mice.
PMCID: PMC1215525  PMID: 16115315

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