Antithrombotic Factor Research Articles

S1P receptor-1 signaling reduces arterial thrombosis by upregulation of endothelial thrombomodulin expression

Abstract Background Sphingosine-1-phosphate (S1P) is a bioactive lipid known for its cardioprotective effects. The extent to which S1P also has effects on arterial thrombosis has not yet been fully elucidated. Another important factor in arterial thrombosis is thrombomodulin (TM), an important endothelial antithrombotic factor. To what extent S1P, TM, and, in addition, platelet adhesion as an initial part influences arterial thrombosis is unclear and the aim of this work. Methods The influence of S1P on human umbilical cord venous endothelial cells (HUVECs) was investigated in cell culture. To investigate effects of S1P and TM on platelet adhesion, flow chamber experiments were performed. In addition, murine arterial thrombus formation was analyzed by intravital microscopy. Results S1P increased TM expression on HUVECs. This effect was abolished by S1P receptor1 (S1PR1) inhibition with W146 (S1P: 1.081 ± 0.091 vs. S1P + W146: 0.951 ± 0.073, normalized to control, p<0.0001). Sphingosine kinase-2 deficient mice (SphK1-/-) lack the kinase primarily producing sphingosine. Accordingly, these animals have less S1P. Here, TM expression was significantly lower in the aorta compared to wild-type mice (WT: 207.2 ± 45.8 pg/g aorta vs. SphK1-/- 124.5 ± 40.2 pg/g aorta, p<0.0001). S1P treatment decreased platelet adhesion from whole blood to endothelial cells in the flow chamber (Con: 100.00 ± 28.09% vs. S1P: 80.91 ± 22.85%, p<0.0001). W146 reversed this effect by S1PR1 inhibition (S1P: 80.91 ± 22.85%, vs. S1P + W146: 118.60 ± 33.65%, p=0.0067). Platelet adhesion to endothelial cells was assessed in the presence of a TM-neutralizing antibody. The TM antibody abolished the anti-adhesive effects of S1P (S1P: 54.79 ± 29.59% vs. S1P+AB: 105.54 ± 35.43%, p=0.0174). TM inhibited intravital murine arterial thrombus formation (time to first occlusion: con: 9.38 ± 1.02 min vs. TM: 60 ± 0 min, p=0.0286). Furthermore, the duration of the first occlusion was significantly shorter and the embolic rate as a marker for thrombus stability was higher. Conclusion We demonstrated that S1P inhibits arterial thrombosis via regulation of endothelial TM. In particular, platelet adhesion to endothelial cells is reduced. This effect is mediated via S1PR1. The extent to which S1PR1 represents a potential antithrombotic target must be clarified in future studies.

Coagulation abnormalities in a prospective cohort of 50 patients with PMM2-congenital disorder of glycosylation.

Given the lack of reliable data on the prevalence of bleeding abnormalities and thrombotic episodes in PMM2-CDG patients, and whether coagulation abnormalities change over time, we prospectively collected and reviewed natural history data. Patients with PMM2-CDG often have abnormal coagulation studies due to glycosylation abnormalities but the frequency of complications resulting from these has not been prospectively studied. We studied fifty individuals enrolled in the Frontiers in Congenital Disorders of Glycosylation Consortium (FCDGC) natural history study with molecularly confirmed diagnosis of PMM2-CDG. We collected data on prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), platelets, factor IX activity (FIX), factor XI activity (FXI), protein C activity (PC), protein S activity (PS) and antithrombin activity (AT). Prothrombotic and antithrombotic factor activities were frequently abnormal in PMM2-CDG patients, including AT, PC, PT, INR, and FXI. AT deficiency was the most common abnormality in 83.3% of patients. AT activity was below 50% in 62.5% of all patients (normal range 80-130%). Interestingly, 16% of the cohort experienced symptoms of spontaneous bleeding and 10% had thrombosis. Stroke-like episodes (SLE) were reported in 18% of patients in our cohort. Based on the linear growth models, on average, patients did not show significant change in AT (n=48; t(23.8)=1.75, p=0.09), FIX (n=36; t(61)=1.60, p=0.12), FXI (n=39; t(22.8)=1.88, p=0.07), PS (n=25; t(28.8)=1.08, p=0.29), PC (n=38; t(68)=1.61, p=0.11), INR (n=44; t(184)=-1.06, p=0.29), or PT (n=43; t(192)=-0.69, p=0.49) over time. AT activity positively correlated with FIX activity. PS activity was significantly lower in males. Based on our natural history data and previous literature, we conclude that caution should be exercised when the AT levels are lower than 65%, as most thrombotic events occur in patients with AT below this level. All five, male PMM2-CDG patients in our cohort who developed thrombosis had abnormal AT levels, ranging between 19% and 63%. Thrombosis was associated with infection in all cases. We did not find significant change in AT levels over time. Several PMM2-CDG patients had an increased bleeding tendency. More long-term follow-up is necessary on coagulation abnormalities and the associated clinical symptoms to provide guidelines for therapy, patient management, and appropriate counseling. Most PMM2-CDG patients display chronic coagulation abnormalities without significant improvement, associated with a frequency of 16% clinical bleeding abnormalities, and 10% thrombotic episodes in patients with severe antithrombin deficiency.

Endothelial-specific loss of Krüppel-Like Factor 4 triggers complement-mediated endothelial injury

Thrombotic microangiopathy (TMA) in the kidney represents the most severe manifestation of kidney microvascular endothelial injury. Despite the source of the inciting event, the diverse clinical forms of kidney TMA share dysregulation of endothelial cell transcripts and complement activation. Here, we show that endothelial-specific knockdown of Krüppel-Like Factor 4 (Klf4)ΔEC, an anti-inflammatory and antithrombotic zinc-finger transcription factor, increases the susceptibility to glomerular endothelial injury and microangiopathy in two genetic murine models that included endothelial nitric oxide synthase knockout mice and aged mice (52 weeks), as well as in a pharmacologic model of TMA using Shiga-toxin 2. In all models, Klf4ΔEC mice exhibit increased pro-thrombotic and pro-inflammatory transcripts, as well as increased complement factors C3 and C5b-9 deposition and histologic features consistent with subacute TMA. Interestingly, complement activation in Klf4ΔEC mice was accompanied by reduced expression of a key KLF4 transcriptional target and membrane bound complement regulatory gene, Cd55. To assess a potential mechanism by which KLF4 might regulate CD55 expression, we performed in silico chromatin immunoprecipitation enrichment analysis of the CD55 promotor and found KLF4 binding sites upstream from the CD55 transcription start site. Using patient-derived kidney biopsy specimens, we found glomerular expression of KLF4 and CD55 was reduced in patients with TMA as compared to control biopsies of the unaffected pole of patient kidneys removed due to kidney cancer. Thus, our data support that endothelial Klf4 is necessary for maintenance of a quiescent glomerular endothelial phenotype and its loss increases susceptibility to complement activation and induction of prothrombotic and pro-inflammatory pathways.

Effects of Saccharides from Arctium lappa L. Root on FeCl3-Induced Arterial Thrombosis via the ERK/NF-κB Signaling Pathway.

Saccharides from Arctium lappa. L. root (ALR-S) is a high-purity fructosaccharide separated from the medicinal plant Arctium lappa. L. root. These compounds showed many pharmacological effects in previous studies. In the present study, the antithrombotic effects of ALR-S in arterial thrombosis via inhibiting platelet adhesion and rebalancing thrombotic and antithrombotic factor expression and secretion were found in rats and human aortic endothelial cells (HAECs). This study also showed that inhibition of oxidative stress (OS), which is closely involved in the expression of coagulation- and thrombosis-related proteins, was involved in the antithrombotic effects of ALR-S. Furthermore, studies using FeCl3-treated HAECs showed that ALR-S induced the abovementioned effects at least partly by blocking the ERK/NF-κB pathway. Moreover, U0126, a specific inhibitor of ERK, exhibited the same effects with ALR-S on a thrombotic process in FeCl3-injured HAECs, suggesting the thrombotic role of the ERK/NF-κB pathway and the antithrombotic role of blocking the ERK/NF-κB pathway by ALR-S. In conclusion, our study revealed that the ERK/NF-κB pathway is a potential therapeutic target in arterial thrombosis and that ALR-S has good characteristics for the cure of arterial thrombosis via regulating the ERK/NF-κB signaling pathway.

Calcification and Thrombosis as Mediators of Bioprosthetic Valve Deterioration

Calcific aortic valve disease is the most common indication for surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) of diseased valves worldwide. 1 For years,...

Enoxaparin prevents fibrin accumulation in liver tissues and attenuates methotrexate-induced liver injury in rats.

Methotrexate (MTX) is a widely used drug for treatment of many malignant, rheumatic, and autoimmune diseases. However, hepatotoxicity remains one of the most serious side effects of MTX. The extrinsic coagulation pathway is activated after tissue injury through the release of tissue factor (TF) which activates a cascade of clotting factors including prothrombin and fibrinogen. Liver sinusoidal endothelial cells express endothelial nitric oxide synthase (eNOS) as a source for nitric oxide (NO) that serves as vasodilator and antithrombotic factor. In the current study, we tested the possible role of coagulation system activation in MTX-induced hepatotoxicity. Our results showed that single-dose administration of MTX significantly altered rat liver functions with concurrent turbulence in redox status. Immunofluorescence staining showed accumulation of fibrin in the periportal hepatocytes and downregulation of eNOS expression in hepatic endothelial and sinusoidal cells following MTX treatment. Moreover, MTX administration increased the expression of inducible nitric oxide synthase (iNOS) and NOSTRIN (eNOS traffic inducer) in the hepatic sinusoids. On the other hand, pre-treatment with enoxaparin rescued against MTX-induced liver injury with subsequent amelioration of liver redox status. Furthermore, it significantly prevented the effect of MTX on the expression of fibrin, iNOS, eNOS, and NOSTRIN. We concluded that liver tissue aggregation of the coagulation product, fibrin, may play a crucial role in the pathogenesis of MTX-induced liver injury.

Engineered Microvasculature in PDMS Networks Using Endothelial Cells Derived from Human Induced Pluripotent Stem Cells

In this study, we used a polydimethylsiloxane (PDMS)-based platform for the generation of intact, perfusion-competent microvascular networks in vitro. COMSOL Multiphysics, a finite-element analysis and simulation software package, was used to obtain simulated velocity, pressure, and shear stress profiles. Transgene-free human induced pluripotent stem cells (hiPSCs) were differentiated into partially arterialized endothelial cells (hiPSC-ECs) in 5 d under completely chemically defined conditions, using the small molecule glycogen synthase kinase 3β inhibitor CHIR99021 and were thoroughly characterized for functionality and arterial-like marker expression. These cells, along with primary human umbilical vein endothelial cells (HUVECs), were seeded in the PDMS system to generate microvascular networks that were subjected to shear stress. Engineered microvessels had patent lumens and expressed VE-cadherin along their periphery. Shear stress caused by flowing medium increased the secretion of nitric oxide and caused endothelial cells s to align and to redistribute actin filaments parallel to the direction of the laminar flow. Shear stress also caused significant increases in gene expression for arterial markers Notch1 and EphrinB2 as well as antithrombotic markers Kruppel-like factor 2 (KLF-2)/4. These changes in response to shear stress in the microvascular platform were observed in hiPSC-EC microvessels but not in microvessels that were derived from HUVECs, which indicated that hiPSC-ECs may be more plastic in modulating their phenotype under flow than are HUVECs. Taken together, we demonstrate the feasibly of generating intact, engineered microvessels in vitro, which replicate some of the key biological features of native microvessels.

Improved vascularization of porous scaffolds through growth factor delivery from heparinized polyethylene glycol hydrogels.

The paper describes the modification and covalent incorporation of heparin into degradable and non-degradable polyethylene glycol hydrogels in a way that provides for the hydrolytic cleavage of the linker for the release of the heparin in original and active form, and in an extended (21-56d) controlled (zero and first order respectively) manner. The successful use of these gels as growth-factor containing and releasing matrices for the improvement of in vivo vascularization holds promise for many potential uses in tissue engineering and regenerative medicine applications, such as vascular grafts and myocardial infarction therapy, where the antithrombotic and/or growth factor binding/potentiating properties are required.

Abstract 10323: Tadalafil Therapy Improves Endothelial Thrombomodulin in Hypoxemic Patients With Pulmonary Arterial Hypertension Associated With the Eisenmenger Syndrome

Introduction: Thrombomodulin (TM) is a plasma membrane chondroitin sulfate proteoglycan acting as a natural endothelial anticoagulant and anti-thrombotic factor. Binding of TM to thrombin leads to protein C activation with subsequent cleavage of activated coagulation factors V and VIII. In pulmonary arterial hypertension (PAH), particularly in hypoxemic patients with Eisenmenger syndrome, endothelial dysfunction is associated with heightened circulating levels of von Willebrand factor antigen (VWF:Ag) and tissue plasminogen activator (t-PA), but decreased TM reflecting diminished endothelial production. Hypothesis: Plasma TM, t-PA, VWF:Ag and functional parameters may be improved in patients with Eisenmenger syndrome subjected to chronic treatment with tadalafil. Methods: Fifteen patients aged 12 to 51 years (median 30 years) were evaluated at baseline, and 90 and 180 days of treatment with oral tadalafil (single daily dose of 40 mg). The functional capacity was accessed using the six-minute walk test and endothelial markers were analyzed by enzyme-linked immunoassays. Results: At baseline, levels of all three endothelial markers were altered in patients compared to controls (respectively, 8.62±3.50 ng/mL vs . 5.13±1.69 ng/mL for t-PA, 121±21 U/dL vs . 94±23 U/dL for VWF:Ag and 1.92±0.49 ng/mL vs . 3.41±0.50 ng/mL for TM. Tadalafil treatment resulted in improvement of exercise capacity (six-minute walked distance, 6MWD) and peripheral oxygen saturation (O 2 Sat), with decreased hematocrit (Htc). Plasma TM increased mildly but significantly, while t-PA level decreased (Table). Conclusion: In the Eisenmenger syndrome, PAH therapy with tadalafil improves not only the physical capacity, O 2 Sat and Htc, but also endothelial markers. The modest increase in circulating TM may reflect improved endothelial TM production and protection against in situ thrombosis, a largely known complication of this syndrome.

Extracranial-Intracranial Bypass Surgery for Stroke Prevention in Hemodynamic Cerebral Ischemia

Context Patients with symptomatic atherosclerotic internal carotid artery occlusion (AICAO) and hemodynamic cerebral ischemia are at high risk for subsequent stroke when treated medically. Objective To test the hypothesis that extracranial-intracranial (EC-IC) bypass surgery, added to best medical therapy, reduces subsequent ipsilateral ischemic stroke in patients with recently symptomatic AICAO and hemodynamic cerebral ischemia. Design Parallel-group, randomized, open-label, blinded-adjudication clinical treatment trial conducted from 2002 to 2010. Setting Forty-nine clinical centers and 18 positron emission tomography (PET) centers in the United States and Canada. The majority were academic medical centers. Participants Patients with arteriographically confirmed AICAO causing hemispheric symptoms within 120 days and hemodynamic cerebral ischemia identified by ipsilateral increased oxygen extraction fraction measured by PET. Of 195 patients who were randomized, 97 were randomized to receive surgery and 98 to no surgery. Follow-up for the primary end point until occurrence, 2 years, or termination of trial was 99% complete. No participant withdrew because of adverse events. Interventions Anastomosis of superficial temporal artery branch to a middle cerebral artery cortical branch for the surgical group. Antithrombotic therapy and risk factor intervention were recommended for all participants. Main Outcome Measure For all participants who were assigned to surgery and received surgery, the combination of (1) all stroke and death from surgery through 30 days after surgery and (2) ipsilateral ischemic stroke within 2 years of randomization. For the nonsurgical group and participants assigned to surgery who did not receive surgery, the combination of (1) all stroke and death from randomization to randomization plus 30 days and (2) ipsilateral ischemic stroke within 2 years of randomization. Results The trial was terminated early for futility. Two-year rates for the primary end point were 21.0% (95% CI, 12.8% to 29.2%; 20 events) for the surgical group and 22.7% (95% CI, 13.9% to 31.6%; 20 events) for the nonsurgical group (P = .78, Z test), a difference of 1.7% (95% CI, −10.4% to 13.8%). Thirty-day rates for ipsilateral ischemic stroke were 14.4% (14/97) in the surgical group and 2.0% (2/98) in the nonsurgical group, a difference of 12.4% (95% CI, 4.9% to 19.9%). Conclusion Among participants with recently symptomatic AICAO and hemodynamic cerebral ischemia, EC-IC bypass surgery plus medical therapy compared with medical therapy alone did not reduce the risk of recurrent ipsilateral ischemic stroke at 2 years. Trial Registration clinicaltrials.gov Identifier: NCT00029146

Are the Laboratory Results (Phenotype) Indicative of a True Genotype Abnormality?

Thrombophilia is the imbalance between the procoagulant systems and the regulatory mechanisms leading to excessive fibrin production and resulting thrombus formation.1,2 These imbalances can be caused by genetic or acquired factors or by a combination of the two.1 However, the process leading to excessive fibrin formation is not as simple as a single factor being disproportionate to the other factors, but rather a multifactorial model, in which many factors interact, leading to the development of thrombosis.1 Therefore, to attempt to determine the correct cause, an assessment of established risk factors must be made.2 Currently, this is an incomplete process because we do not know all of the responsible factors. But we do know several of the major factors.2 One of the main factors analyzed in most assessments is protein S (PS).2 A deficiency of PS seems to be a major contributor to thrombophilia, yet its biochemistry, physiology, and pathobiology are complex.4,5 PS functions as an antithrombotic factor by an activated protein C (APC)-dependent mechanism and an APC-independent mechanism.2,4,6 Its ultimate antithrombotic role is to down-regulate thrombin formation. PS also seems to have a role in fibrinolysis, complement regulation, and other defense mechanisms.6 The importance of any of these mechanisms in vivo is unknown.6 PS is a nonenzymatic cofactor that binds in equilibrium to a large complement protein, C4b-binding protein.6 Only the unbound (or “free”) form of PS has APC cofactor activity on the phospholipid surface to inactivate factors Va and VIIIa.2,4 Thrombophilia is a defined as a “complex disease” in which multiple factors together have a major role in the disease process. Today we understand only the basics of causation of the disease process. There are many ways …

Farnesyl pyrophosphate is an endogenous antagonist to ADP-stimulated P2Y12 receptor-mediated platelet aggregation

Farnesyl pyrophosphate (FPP) is an intermediate in cholesterol biosynthesis, and it has also been reported to activate platelet LPA (lysophosphatidic acid) receptors. The aim of this study was to investigate the role of extracellular FPP in platelet aggregation. Human platelets were studied with light transmission aggregometry, flow cytometry and [³⁵S]GTPγS binding assays. As shown previously, FPP could potentiate LPA-stimulated shape change. Surprisingly, FPP also acted as a selective insurmountable antagonist to ADP-induced platelet aggregation. FPP inhibited ADP-induced expression of P-selectin and the activated glycoprotein (Gp)IIb/IIIa receptor. FPP blocked ADP-induced inhibition of cAMP accumulation and [³⁵S]GTPγS binding in platelets. In Chinese hamster ovary cells expressing the P2Y₁₂ receptor, FPP caused a rightward shift of the [³⁵S]GTPγS binding curve. In Sf9 insect cells expressing the human P2Y₁₂ receptor, FPP showed a concentration-dependent, although incomplete inhibition of [³H]PSB-0413 binding. Docking of FPP in a P2Y₁₂ receptor model revealed molecular similarities with ADP and a good fit into the binding pocket for ADP. In conclusion, FPP is an insurmountable antagonist of ADP-induced platelet aggregation mediated by the P2Y₁₂ receptor. It could be an endogenous antithrombotic factor modulating the strong platelet aggregatory effects of ADP in a manner similar to the use of clopidogrel, prasugrel or ticagrelor in the treatment of ischaemic heart disease.

Adiponectin Inhibits Hyperlipidemia-Induced Platelet Aggregation via Attenuating Oxidative/Nitrative Stress

Adiponectin acts as an endogenous antithrombotic factor. However, the mechanisms underlying the inhibition of platelet aggregation by adiponectin still remain elusive. The present study was designed to test whether adiponectin inhibits platelet aggregation by attenuation of oxidative/nitrative stress. Adult rats were fed a regular or high-fat diet for 14 weeks. The platelet was immediately separated and stimulated with recombinant full-length adiponectin (rAPN) or not. The platelet aggregation, nitric oxide (NO) and superoxide production, endothelial nitric oxide synthase (eNOS)/inducible NOS (iNOS) expression, and antioxidant capacity were determined. Treatment with rAPN inhibited hyperlipidemia-induced platelet aggregation (P<0.05). Interestingly, total NO, a crucial molecule depressing platelet aggregation and thrombus formation?was significantly reduced, rather than increased in rAPN-treated platelets. Treatment with rAPN markedly decreased superoxide production (-62 %, P<0.05) and enhanced antioxidant capacity (+38 %, P<0.05) in hyperlipidemic platelets. Hyperlipidemia-induced reduced eNOS phosphorylation and increased iNOS expression were significantly reversed following rAPN treatment (P<0.05, P<0.01, respectively). Taken together, these data suggest that adiponectin is an adipokine that suppresses platelet aggregation by enhancing eNOS activation and attenuating oxidative/nitrative stress including blocking iNOS expression and superoxide production.

Clotting Factor Gene Polymorphisms and Colorectal Cancer Risk

Increased coagulation has been associated with cancer onset and progression. Mainly small studies have addressed the association between clotting factor gene polymorphisms and the onset of colorectal cancer. We examined the association between six well-known clotting factor gene polymorphisms and colorectal cancer risk in a large case-control study. Factor V Leiden (rs6025), prothrombin G20210A (rs1799963), PAI-1 4G/5G (rs1799889), MTHFR 677C>T (rs1801133), fibrinogen gamma 10034C>T (rs2066865), and factor XIII Val34Leu (rs5985) were genotyped in 1,801 patients with colorectal cancer and 1,853 healthy controls from a large German population-based study. The risk of colorectal cancer associated with gene variants was determined by calculating odds ratios (ORs) and their 95% CIs using logistic regression. Homozygous carriers of the prothrombotic factor V Leiden polymorphism showed a 5.8-fold increased risk (95% CI, 1.69 to 19.72) for colorectal cancer compared with noncarriers. A 30% reduced risk was found for heterozygous carriers of factor V Leiden (OR = 0.68; 95% CI, 0.52 to 0.90) and prothrombin G20210A (OR = 0.69; 95% CI, 0.49 to 0.96), implying an advantage for slightly increased thrombin generation. Carriers of the antithrombotic factor XIII Val34Leu polymorphism showed a 15% reduced risk of developing colorectal cancer (OR = 0.85; 95% CI, 0.74 to 0.97) compared with noncarriers. Our results did not support an effect of PAI-1 4G/5G, MTHFR 677C>T, and fibrinogen gamma 10034C>T on colorectal cancer risk. Our results support a role of clotting factor polymorphisms and thereby the coagulation system in the risk of colorectal cancer.

E0473 Rapid re-endothelialization and anti-intimal hyperplasia coronary stent system with a novel biomacromolecular prohealing coating

BackgroundRapid healing of endothelium on the coronary stent is a crucial method to prevent late stent thrombosis, a rare but life-threatening complication of drug eluting stents (DES). Here we developed...

Is tetrahydrobiopterin a therapeutic option in diabetic hypertensive patients?

Nitric oxide (NO) is an important regulator of vascular tone, and is also an antithrombotic, anti-inflammatory, antiproliferative, and antiatherogenic factor. Endothelial function is altered in patients with coronary artery disease, stroke, and peripheral artery disease, and endothelial dysfunction correlates with the risk factor profile for a patient. Hypertension and type 2 diabetes are risk factors for vascular disease, and are both pathologies characterized by loss of NO activity. Indeed, endothelial dysfunction is usually present in diabetic and/or hypertensive patients. Tetrahydrobiopterin is an essential cofactor for the NO synthase enzyme, and insufficiency of this cofactor leads to uncoupling of the enzyme, release of superoxide, endothelial dysfunction, progression of hypertension, and finally, proatherogenic effects. Tetrahydrobiopterin is also an important mediator of NO synthase regulation in type 2 diabetes and hypertension, and may be a rational therapeutic target to restore endothelial function and prevent vascular disease in these patients. The aim of this paper is to review the rationale for therapeutic strategies directed to biopterins as a target for vascular disease in type 2 diabetic hypertensive patients.

The appearance of dermcidin isoform 2, a novel platelet aggregating agent in the circulation in acute myocardial infarction that inhibits insulin synthesis and the restoration by acetyl salicylic acid of its effects

Hyperglycemia with severe reduction of plasma insulin level is frequently associated with acute ischemic heart disease. Since insulin is reported to be an anti thrombotic humoral factor, the mechanism of the impaired insulin synthesis was investigated. The plasma from the patients with acute myocardial infarction (AMI) was analyzed by SDS-polyacrylamide gel electrophoresis. Dermcidin isoform 2 (dermcidin) was determined by enzyme linked immunosorbent assay. Insulin synthesis was determined by in vitro translation of glucose induced insulin mRNA synthesis in the pancreatic β cells. Nitric oxide (NO) was determined by methemoglobin method. SDS-polyacrylamide gel electrophoresis of AMI plasma demonstrated the presence of a novel protein band of Mr 11 kDa that was determined to be dermcidin. Addition of 0.1 μM dermcidin inhibited insulin synthesis by >65 fold compared to control through the inhibition of NO synthesis in the pancreatic cells. The oral administration of 150 mg acetyl salicylic acid (aspirin) to the AMI patients increased the plasma insulin level from 13 (median) to 143 μunits/dl (median) with concomitant decrease of plasma dermcidin level from 112 to 9 nM in these patients within 12 h. It was also found that while the injection of 3.0 ± 0.05 (n = 10) nmol dermcidin with 0.25 ± 0.03 μmol ADP/g body weight caused coronary thrombus in mice, ADP itself at this concentration failed to produce thrombus. These results indicated that dermcidin was a novel platelet aggregating agent, and potentiated the ADP induced thrombosis in the animal model as well as acutely inhibited glucose induced insulin synthesis.

Entering the Era of Non-Basic P1 Site Groups: Discovery of Xarelto&amp;#8482; (Rivaroxaban)

Several clinical candidates have now emerged as a result of an intense search for orally available, antithrombotic factor Xa inhibitors. This review highlights the discovery of XareltoTM (Rivaroxaban) starting from an initial tetrahydrophthalimide screening hit. The major breakthrough was the finding that a chlorothiophene moiety can undergo an interaction in the S1 binding site thus leading to high potency combined with favorable oral bioavailability. The binding mode of this P1 moiety is discussed, and further non-basic S1 binders of this new type are reviewed.

Antidote‐Controlled Antithrombotic Therapy Targeting Factor IXa and Von Willebrand Factor

Thrombotic disorders and their common clinical phenotypes of acute myocardial infarction, ischemic stroke, and venous thromboembolism are the proximate cause of substantial morbidity, mortality, and health care expenditures worldwide. Accordingly, therapies designed to attenuate thrombus initiation and propagation, reflecting integrated platelet-mediated and coagulation protease-mediated events, respectively, represent a standard of care. Unfortunately, there are numerous inherent limitations of existing therapies that include target nonselectivity, variable onset and offset of pharmacodynamic effects, a narrow efficacy-safety profile, and the absence of a safe and reliable platform for either accurate titration, based on existing patient-specific, disease-specific, and clinical conditions, or active reversibility. Herein, we summarize our experience with oligonucleotide antithrombotic agents and their complementary antidotes, targeting the platelet adhesive protein von Willebrand factor and the pivotal coagulation protease factor IXa.

혈관 생리 활성에 미치는 alliin의 효능

고대부터 식품으로 많이 이용되어 왔던 마늘의 성분중의 하나인 alliin의 혈관 생리활성을 조사하기 위해 다양한 실험을 수행하였다. Alliin은 혈관내피세포의 증식과 이동을 증진시키는 기능이 있으며, 이는 alliin이 혈관형성을 촉진하고 혈관의 상처 치유에 도움을 줄 수 있음을 의미한다. 또한 alliin은 염증반응을 일으키는 과정에 나타나는 THP-1 세포의 혈관내피세포 부착을 억제하며, 혈전을 형성하는 THP-1 동종세포간 응집을 억제하는 기능도 갖고 있음이 확인되었다. 이와 같은 alliin의 세포 기능은 혈관의 주요 질환인 동맥경화의 발생 및 뇌졸증이나 심근경색의 원인이 되는 혈전의 형성 등을 억제할 수 있음을 의미한다. 한편 혈관의 주요 조절자 중의 하나인 산화질소의 생산에는 alliin이 관여하지 않음을 확인하였다. 종합해 보면, alliin은 혈관세포의 여러 가지 생리기능을 조절하는 혈관생리기능 개선제로 활용할 가능성이 있는 물질이다. Little is known about the cardiovascular roles of alliin, a functional component in garlic that has been used as food material. Thus, we examined a broad range of cardiovascular activities of alliin in this study. From our in vitro experiments, alliin was determined to act as a stimulant to induce endothelial cell proliferation and endothelial cell migration. Since endothelial cell proliferation and migration are highly associated with angiogenesis and wound healing, alliin is suggested as a regulator to control angiogenesis and wound healing. In addition, alliin was elucidated to prevent lipopolysaccharide (LPS)-induced adhesion of THP-1 leukocytes to endothelial cells and LPS-induced homotypic THP-1 cell aggregation. These inhibitory effects indicate that alliin is likely to act as an anti-atherosclerotic and anti-thrombotic factor, because leukocytic adhesion to endothelial cells and homotypic leukocyte aggregation are highly associated with atherosclerosis and thrombosis, respectively. Our additional findings show that alliin has no effect on the production of nitric oxide (NO), an important vasoregulator. In conclusion, alliin is suggested as a regulator for controlling various cardiovascular functions.