Induction of GRP78 by valproic acid is dependent upon histone deacetylase inhibition.

Valproic (2-propylpentanoic) acid is a commonly used drug in the treatment of bipolar disorder and epilepsy. The molecular mechanism that underlies its clinical efficacy remains controversial and is complicated by the broad range of intracellular effects of valproic acid, including its ability to inhibit histone deacetylase (HDAC) and induce protein chaperone expression. Here we show that an established HDAC inhibitor, trichostatin A, promotes ER chaperone expression in HEK293 cells.

Beyond heparin and warfarin: the new generation of anticoagulants.

Heparin and warfarin are widely used for the prevention and treatment of venous and arterial thromboembolism. Although effective, both agents have important limitations; for example, both drugs must be monitored, which is inconvenient for patients and for physicians. Heparin requires parenteral administration and can cause heparin-induced thrombocytopenia, an immune-mediated process that can lead to life-threatening thrombosis.

Analysis of inhibition rate enhancement by covalent linkage of antithrombin to heparin as a potential predictor of reaction mechanism.

Antithrombin (AT) inhibition of coagulation enzymes is catalyzed by unfractionated heparin (UFH) and other heparinoids. Reaction proceeds either via conformational activation of the inhibitor or template-mediated binding of both inhibitor and protease. We investigated if the relative inhibition rates of AT + UFH and covalent AT-heparin conjugate (ATH) with coagulation factors might be indicative of the mechanism involved.

Activated protein C in sepsis and beyond: update 2006.

Activated protein C (APC), a plasma serine protease, is best known for its ability to inhibit blood clot formation. APC acts as an anticoagulant by degrading coagulation cofactors Va and VIIIa, thereby attenuating the coagulation cascade. Over the past 15 years, impressive research advances have provided novel insights into the diverse biological activities of this molecule.

Protein adsorption on polyurethane catheters modified with a novel antithrombin-heparin covalent complex.

Highly anticoagulant covalent antithrombin-heparin complex (ATH) was covalently grafted onto polyurethane catheters to suppress adsorption/activation of procoagulant proteins and enhance adsorption/activation of anticoagulant proteins for blood compatibility. Consistency of catheter coating was demonstrated using immunohistochemical visualization of ATH. The ability of the resulting immobilized ATH heparin chains to bind antithrombin (AT) from plasma, as measured by binding of (125)I-radiolabeled AT, was greater than that for commercially-available heparin-coated catheters, and much greater than for uncoated catheters.

HD1, a thrombin-directed aptamer, binds exosite 1 on prothrombin with high affinity and inhibits its activation by prothrombinase.

Incorporation of prothrombin into the prothrombinase complex is essential for rapid thrombin generation at sites of vascular injury. Prothrombin binds directly to anionic phospholipid membrane surfaces where it interacts with the enzyme, factor Xa, and its cofactor, factor Va. We demonstrate that HD1, a thrombin-directed aptamer, binds prothrombin and thrombin with similar affinities (K(d) values of 86 and 34 nm, respectively) and attenuates prothrombin activation by prothrombinase by over 90% without altering the activation pathway.

Covalent antithrombin-heparin complexes.

Unfractionated heparin (UFH) and low molecular weight heparin (LMWH) have been utilized as primary anticoagulants for thrombosis prophylaxis and treatment. However, a number of biophysical and safety limitations have led to development of new anticoagulants. Covalent antithrombin-heparin (ATH) complexes may address many of these issues.

Structural effects of a covalent linkage between antithrombin and heparin: covalent N-terminus attachment of heparin enhances the maintenance of antithrombin's activated state.

We have produced a molecule comprising of permanently-activated covalently linked antithrombin and heparin (ATH). This study was designed to elucidate the covalent linkage point(s) for heparin on antithrombin and conformational properties of the ATH molecule. ATH was produced using Schiff base/Amadori rearrangement by incubating antithrombin with unfractionated heparin for 14 d at 40 degrees C.

Comparison of fixed-dose weight-adjusted unfractionated heparin and low-molecular-weight heparin for acute treatment of venous thromboembolism.

Context: When unfractionated heparin is used to treat acute venous thromboembolism, it is usually administered by intravenous infusion with coagulation monitoring, which requires hospitalization. However, subcutaneous administration of fixed-dose, weight-adjusted, unfractionated heparin may be suitable for inpatient and outpatient treatment of venous thromboembolism.

Objective: To determine if fixed-dose, weight-adjusted, subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin for treatment of venous thromboembolism.

Chronic performance of polyurethane catheters covalently coated with ATH complex: a rabbit jugular vein model.

Covalent complexes of antithrombin (AT) and heparin (ATH) have superb anticoagulant activity towards thrombin and factor Xa. Stability of polyurethane central venous catheters covalently modified with radiolabeled ATH was studied using a roller pump with saline or protease P-5147. Saline wash removed loosely bound ATH molecules to decrease graft density from 26 to 12 pmol/cm2.

Selective cleavage of heparin using aqueous 2-hydroxypyridine: production of an aldose-terminating fragment with high anticoagulant activity.

Unfractionated heparin (UFH) was partially depolymerized by heating at 115 degrees C with aqueous 2-hydroxypyridine. Compared to starting UFH, no significant loss of anticoagulant (anti-Xa) activity was observed. Products consisted of polysaccharide fragments and small quantities of ammonia, sulfate, and hexuronic acid.

An evaluation of D-dimer in the diagnosis of pulmonary embolism: a randomized trial.

Background: It may be safe to omit additional diagnostic testing in selected patients with suspected pulmonary embolism (PE) who have a negative D-dimer test, but this approach has never been evaluated in a randomized, controlled trial.

Objective: To determine if additional diagnostic testing can be safely withheld in patients with suspected PE who have negative erythrocyte agglutination D-dimer test results.

Design: Randomized comparisons in 2 subgroups of a prospective multicenter study.

Heparin synergistically enhances interleukin-11 signaling through up-regulation of the MAPK pathway.

Using an animal model of heparin-induced osteoporosis we previously demonstrated that heparin causes bone loss, in part, by increasing osteoclast number and activity. Furthermore, we found that, although heparin alone has no effect, it is able to synergistically enhance Interleukin-11 (IL-11)-induced signal transducer and activator of transcription 3 (STAT3) activation and thus increase osteoclast formation in vitro. In the present study, we examine the effect of various serine kinase inhibitors on the ability of heparin to act synergistically with IL-11.

Genetic determinants of cancer coagulopathy, angiogenesis and disease progression.

Progression of human malignancies is accompanied by vascular events, such as formation and remodeling of blood vessels and systemic coagulopathy. Though long appreciated as comorbidity of cancer (Trousseau syndrome), vascular involvement is increasingly recognized as a central pathogenetic mechanism of tumor growth, invasion and metastasis. The major outstanding question in relation to this role has been, whether vascular perturbations are simply a reaction to the conditions of the tumor microenvironment, or are linked to the known genetic lesions causal for the onset and progression of malignancy.

Emerging anticoagulants: mechanism of action and future potential.

Medical needs associated with diverse thromboembolic conditions are not fully met by currently available anticoagulants. Of those, unfractionated heparin (UFH) is gradually replaced by low molecular weight heparin (LMWH) for prevention and treatment of venous thromboembolism and acute coronary syndromes, along with supportive treatment with oral anticoagulants, such as warfarin derivatives. While generally effective these agents have several shortcomings involving compliance, delivery, efficacy and safety considerations in various disease settings, and for these reasons new anticoagulants are sought, to target more specifically the critical effectors and steps in the blood coagulation process, namely: (i) initiation, (ii) propagation and (iii) the phase of thrombin activity.

Biodistribution of covalent antithrombin-heparin complexes.

We have developed a covalent antithrombin-heparin (ATH) complex with advantages compared to non-covalent antithrombin:heparin (AT:H) mixtures. In addition to increased activity, ATH has a longer intravenous half-life that is partly due to reduced plasma protein binding. Given ATH's altered clearance, we investigated biodistribution of ATH in vivo.

A disconnect between antitumor and antiangiogenic effects of fluvastatin in vitro and in vivo.

The possible role of statins in cancer is controversial. Indeed, among the multiplicity of biological effects ascribed to these widely used cholesterol lowering agents some could, at least in theory, inhibit tumor growth (e.g.

Tissue factor in cancer and angiogenesis: the molecular link between genetic tumor progression, tumor neovascularization, and cancer coagulopathy.

Tissue factor (TF), the primary cellular initiator of blood coagulation, is also involved in cancer-related processes such as hypercoagulability (Trousseau syndrome), tumor growth, angiogenesis, and metastasis. Indeed, elevated TF expression by cancer cells and their associated endothelial cells has been reported frequently. Oncogenic events in cancer cells (e.

Glucosamine-induced endoplasmic reticulum dysfunction is associated with accelerated atherosclerosis in a hyperglycemic mouse model.

Diabetes is a major independent risk factor for cardiovascular disease and stroke; however, the molecular and cellular mechanisms by which diabetes contributes to the development of vascular disease are not fully understood. Our previous studies demonstrated that endoplasmic reticulum (ER) stress-inducing agents, including homocysteine, promote lipid accumulation and activate inflammatory pathways-the hallmark features of atherosclerosis. We hypothesize that the accumulation of intracellular glucosamine observed in diabetes may also promote atherogenesis via a mechanism that involves ER stress.

Perioperative management of oral anticoagulation.

Based on an individual assessment of risk factors for arterial or venous thrombosis and the risk of postoperative bleeding, this article outlines the preoperative and postoperative approach to anticoagulant management. Preceding this is a brief description of the therapies most commonly used in the perioperative period. The prevention of arterial thromboembolism is considered separately from the prevention of venous thrombosis.

Pharmacology and clinical potential of direct thrombin inhibitors.

Direct thrombin inhibitors represent a new class of anticoagulants that bind directly to thrombin and block the enzyme's interactions with its substrates. These agents have been developed, at least in part, to overcome the limitations of heparin and vitamin K antagonists. This paper (a) reviews why thrombin is an ideal target for new anticoagulants, (b) describes the pharmacological profiles of the various direct thrombin inhibitors, (c) outlines the potential mechanistic advantages of parenteral direct thrombin inhibitors over heparin, (d) defines the potential benefits of ximelagatran, the first orally active direct thrombin inhibitor, over vitamin K antagonists, and (e) provides clinical perspective on the strengths and weaknesses of the various parenteral and oral direct thrombin inhibitors.

Regulation of tissue factor and angiogenesis-related genes by changes in cell shape.

During development, tissue injury, and cancer, epithelial cells engage in communication with the vascular system by using several molecular mediators acting directly or through changes in the haemostatic system.The latter category is epitomised by the procoagulant cellular receptor known as tissue factor (TF). Here, we show that when cellular architecture is altered by a shift in culture conditions from monolayer to three-dimensional multicellular spheroids, expression of multiple angiogenesis effectors (VEGF, TSP-1, TSP-2, Ang-1, and TF) is profoundly altered.

Is cancer stem cell a cell, or a multicellular unit capable of inducing angiogenesis?

Cancer stem cells are presently viewed as carriers of the growth initiating potential, repopulation capability and drug resistance in tumors. However, many of these fundamental properties of cancer are host-related, modified by cell-cell interactions and/or dependent on angiogenesis. Indeed, it is well established that co-injection of cancer cells with their irradiated (mitotically dead) counterparts, or with Matrigel can significantly increase their tumor forming capacity (i.