Pathogenesis Of Thromboembolic Disease Research Articles

Evaluation of antioxidant activity of NG-R1 saponin against bacterial cells in induced oxidative stress - a preliminary study.

Notoginsenoside R1 (NG-R1) is isolated from Panax notoginseng, a medicinal herb well-known for its long use in traditional Chinese medicine. NG-R1 is relatively under-studied in research on bacteria. The aim of the study was to investigate antioxidant properties of NG-R1 saponin of selected bacterial strains of intestinal microbiota that may be involved in the pathogenesis of thromboembolic diseases. Enterococcus faecalis and Escherichia coli were used in the study. The study determined the concentration of hydroperoxides, the level of lipid peroxidation, as well as carbonyl groups and free thiol groups. The research carried out in this way will allow determination of the influence of the above factors on bacteria living in intestinal microbiota. An evaluation of selected parameters of oxidative stress allowed to check whether the tested compound could reduce the pro-thrombotic activity of bacteria that were stimulated with H2O2. It was found that NG-R1 reduced hydroperoxide levels in both types of bacteria. In turn, lipid peroxidation initiated by H2O2 was suppressed by NG-R1. Hydrogen peroxide led to a strong increase in the level of carbonyl groups in Enterococcus faecalis and, to a lesser extent, in Escherichia coli. The addition of NG-R1 to the medium significantly reduced the level of carbonyls. Additionally, NG-R1 also induced a significant increase in the level of free thiol groups. Obtained results indicate that NG-R1 may have a protective effect on the intestinal microbiom through mechanisms involving changes in the redox state.

Biomarkers of Hemostatic Dysregulation and Inflammation in Lymphoma: Potential Relevance to Thrombogenesis

INTRODUCTION: The prevalence of thrombotic complications in lymphoma patients ranges from 1.5% up to 59.5%. Lymphoma patients have a 10-fold higher risk for the development of venous thrombosis than patients with lung and gastrointestinal cancers. The pathogenesis of thromboembolic disease in hematological malignancies is complex and multifactorial and can be due to the underlying disorder or related to therapy. A number of biomarkers are associated with the occurence of VTE in cancer patients. Biomarkers reflect activation of coagulation and increased inflammatory potential. This study aimed to profile hemostatic and inflammatory biomarkers in patients with Hodgkin lymphoma, non-Hodgkin lymphoma, and chronic lymphocytic leukemia/ small lymphocytic lymphoma. METHODS: Citrated plasma samples were collected from lymphoma patients (n=96) under an IRB approved protocol Clinic for hematology, Lymphoma Center, University of Belgrade in Serbia. Samples were shipped to Loyola University Chicago and analyzed in batches via commercially available ELISA kits to profile biomarkers of coagulation activation and inflammation. Markers in Coagulation Activation: von Willebrand Factor (vWF), Factor XIIIa, Protein S, β2Glycoprotein I (β2GPI), D-dimer, Microparticles (MP), Urokinase-type Plasminogen Activator Antigen (uPA), Fibronectin. Markers of Inflammation included: Human Tumor Necrosis Factor- α (TNF- α), C-Reactive Protein (CRP), Plasminogen Activator Inhibitor Type 1 (PAI-1). The lymphoma patient population for each biomarker was compared to normal human pooled plasma (repeated 3 times for each biomarker), which consisted of 25 male and 25 females. RESULTS: The mean patients' age was 56 years (range, 19-80 years); 52.4% were males. Most patients were newly diagnosed and had advanced stage disease. A total of 42 patients (43.8%) had high-grade NHL; 17 (17.7%) had low-grade NHL; 24 (25.0%) had HLL; 7(7.3%) had HL; 6 (6.3%) had other forms. Lymphoma patients had significantly dysregulated following markers of coagulation: vWF, β2GPI, D-dimer, MP, uPA, and Fibronectin (Figure 1) (p<0.001 for all in comparison to controls). TNF-α and CRP as markers of inflammation were also significantly increased in lymphoma patients (Figure 1) (p<0.001 for both in comparison to controls). In lymphoma population 12 patients had thrombosis. Patients with thrombosis had significantly higher Factor XIIIa in comparison to lymphoma patients without thrombosis (106±9 vs. 85±256; p<0.001). CONCLUSION: Hemostatic dysregulation and inflammation is present in lymphoma patients, which may reflect increased thrombogenic potential. Further studies are required to link clinical data and biomarker levels, with special emphasis on the involvement of FXIII in the development of thrombotic events in lymphoma patients. Biomarker profiling of lymphoma patients will also help in the understanding of the pathophysiologic mechanisms involved in the observed thrombotic complications and differentiating the sub-groups. Figure 1 Disclosures No relevant conflicts of interest to declare.

Thrombosis and hemostatic abnormalities in hematological malignancies.

There is a paucity of data that pertain to thrombosis in patients with hematological malignancies. Recent studies showed that patients with lymphoma, multiple myeloma, and acute leukemia have an increased thrombotic risk, particularly at the time of diagnosis and during chemotherapy. We searched the PubMed database for articles on thromboembolic complications in patients with hematological malignancies published between 1996 and 2013. The incidence of thrombotic events is variable, and is influenced by the type and the stage of hematological malignancy, the antitumor therapy, and the use of central venous devices. The pathogenesis of thromboembolic disease in hematological malignancies is multifactorial. Tumor cell-derived procoagulant, fibrinolytic, or proteolytic factors, and inflammatory cytokines affect clotting activation, and chemotherapy and immunomodulatory drugs increase the thrombotic risk in patients with lymphoma, acute leukemia, and multiple myeloma. Infections might also contribute to the pathogenesis of the thromboembolic complications: endotoxins from gram-negative bacteria induce the release of tissue factor, tumor necrosis factor and interleukin-1b, and gram-positive organisms can release bacterial mucopolysaccharides that directly activate factor XII. In the setting of plasma cell dyscrasias, hyperviscosity, decreased fibrinolysis, procoagulant autoantibody production, inflammatory cytokines, acquired activated protein C resistance, and the prothrombotic effects of antimyeloma agents might be the cause of thromboembolic complications. Anticoagulant therapy is very complicated because of high risk of hemorrhage. Therefore, an accurate estimate of a patient's thrombotic risk is essential to allow physicians to target thromboprophylaxis in high-risk patients.

Thromboembolic Complications in Malignant Haematological Disorders

It is well known that solid cancers are associated with thromboembolic complications, but recent studies have shown that the incidence of thrombosis may be as high (or even higher) in patients with malignant haematological disorders. However, this may be obscured by the significant morbidity and mortality due to other complications of haematological malignancies, such as bleeding and infections. The vast majority of patients with haematological neoplasias also have clinically silent haemostatic abnormalities, but some may show clinical manifestations, including venous thromboembolism, pulmonary embolism, disseminated intravascular coagulation and life-threatening thrombohaemorrhagic syndrome in acute leukaemias. The pathogenesis of thromboembolic disease in haematological malignancies is complex and multifactorial: tumour cell-derived procoagulant, fibrinolytic or proteolytic factors and inflammatory cytokines affect clotting activation, and chemotherapy and anti-angiogenic drugs increase thrombotic risk in patients with lymphoma, acute leukaemia and multiple myeloma. Infectious complications are another important factor: endotoxins from gram-negative bacteria induce the release of tissue factor (TF), Tumor Necrosis Factor (TNF) and interleukin-1b (IL-1b), and gram-positive organisms can release bacterial mucopolysaccharides that directly activate factor XII. Leukaemic patients may be affected by other prothrombotic factors, including hyperleukocytosis, increased TF expression and activation, and the prothrombotic properties of therapeutic agents such as all-trans retinoic acid and L-asparaginase, which can induce thrombosis involving multiple organs. The very high risk of haemorrhaging in these patients warrants prospective randomised trials evaluating optimal anti-thrombotic prophylaxis and treatment.

Chiari’s network: review of the literature

The Chiari network, present in approximately 2% of the population, and is a reticulated network of fibers originating from the Eustachian connecting to different parts of the right atrium. Its presence results from incomplete reabsorption of the right valve of the sinus venosus. Chiari's network is often clinically insignificant. However, it has been reported to be involved in the pathogenesis of thromboembolic disease, endocarditis, arrhythmias, and entrapment of catheters upon percutaneous intervention. While initially discovered and researched using autopsy dissections, Chiari's network is often found as an incidental finding on diagnostic imaging studies, thus providing new methods for studying its incidence and clinical significance.

Acute Myeloid Leukemia with Mutated NPM1 Presenting with Life-Threatening, Either Arterial or Venous, Thromboembolism: a Report of 4 Cases.

Abstract 4135Acute myeloid leukemia (AML) expressing mutated NPM1 gene and cytoplasmic nucleophosmin (NPMc+ AML) [Falini B et al, NEJM 2005;352:254-266] is a new entity of WHO classification that shows distinctive biological and clinical features. AML with mutated NPM1 usually presents with a high white blood cell count; the bone marrow biopsy is usually markedly hypercellular and leukemic cells frequently show myelomonocytic or monocytic features, with dysplasia and involvement of two or more cell lineages in about 25% of cases. Lack, or low expression, of CD34 in over 90% of cases is the most distinctive immunophenotypic feature of NPM1-mutated AML and is independent of leukemic cell maturation. NPM1 gene mutation without concomitant FLT3-ITD identify a subgroup of AML patients with a favorable prognosis and has been associated with an approximately 50-60% probability of survival at 5 years in younger patients. Here we report 4 out of 41 (10%) patients, admitted at our Hospital in the last year, with new-diagnosed AML with mutated NPM1 presenting with life-threatening thromboembolic (either arterial or venous) events. The main characteristics of these patients are summarized in Table 1. The patients had neither personal nor family history concerning thromboembolism. Hyperleukocytosis was a common feature of the vast majority of NPM1-mutated AML patients at diagnosis. Immunophenotypic analysis did not show a peculiar phenotype in these patients.Table 1Characteristics of patients with NPM1-mutated AML and thrombosis.Case report noAgeSex (M/F)FAB subtypeWBC/mmcType of thrombosisSite of thrombosis141FM114970arterialAnterior interventricular branch of left coronary artery256MM493990arterialexternal iliac and femoral (right limb)363MM2113000deep venousgreat saphenous veins (bilateral)473FM4190000deep venousiliac and femoralIn two patients (cases 1 and 2), the arterial thromboembolic event (acute myocardial infarction and acute ischemia of right lower limb, respectively) presented about one month before diagnosis of leukemia. In the other 2 patients (cases 3 and 4), deep venous thromboembolism was concomitant with the diagnosis of leukemia. One patient (case 4), who could not initiate chemotherapy for severe concomitant renal failure, died few days after diagnosis. The other patients recovered from the acute event and upon diagnosis of leukemia were promptly treated with standard polychemotherapy which allowed to obtain complete hematological remission associated with complete resolution of the thromboembolic event. The clinical course after chemotherapeutic treatment of the patients outlines the importance and life saving role of early chemotherapy even under adverse circumstances. The pathogenesis of thromboembolic disease in hematological malignancies is complex and multifactorial: tumor cell-derived procoagulant, fibrinolytic or proteolytic factors and inflammatory cytokines affect clotting activation. Other important factors include infectious complications and hyperleukocytosis. However, large vessel thrombosis is a very rare clinical presentation. Our report of severe thromboembolic events at presentation in AML with mutated NPM1 suggests some still unidentified biological features of this leukemia which we are currently investigating. Disclosures:No relevant conflicts of interest to declare.

Acidic Citrate Stabilizes Blood Samples for Assay of Total Homocysteine

Homocysteine is a sulfhydryl-containing amino acid, formed by demethylation of the essential amino acid methionine. Homocysteine is either transsulfurated to cysteine or is remethylated to methionine by methionine synthase. Excess intracellular homocysteine is likely to be transported to the extracellular compartment (1). Increasing evidence indicates that homocysteine is implicated in the pathogenesis of thromboembolic diseases. Several case control studies have shown a relationship between increased total plasma homocysteine (tHcy) concentrations and an increased risk of arterial (2)(3)(4) and venous thrombosis (5)(6)(7)(8). An increase of the tHcy concentration of 5 μmol/L is associated with 1.5–1.9 times increased risk for coronary artery or cerebrovascular disease (9). These values indicate that small differences might be of clinical importance. Therefore, practical standardized conditions for handling blood specimens for tHcy determination are required. In most studies, blood is drawn in tubes containing K3EDTA. The whole-blood sample is immediately put on crushed ice and then centrifuged as soon as possible to prevent an increase of tHcy concentrations. This tHcy increase is caused by ongoing homocysteine metabolism in blood cells, the majority of which are red blood cells (10)(11). This blood handling procedure is not practical, particularly when larger studies are conducted outside a hospital setting; even in a routine clinical setting, this protocol might be hard to put into practice. To find an alternative, more suitable blood-collection medium, we investigated the effect of different blood-collection media on tHcy production when whole blood is kept at room temperature for 6 h. Blood was drawn by venipuncture of the antecubital vein from laboratory coworkers or from consecutive patients who visited the outpatient clinics of the Leyenburg Hospital in The Hague for various reasons, unknown to the authors. Informed consent was obtained in accordance …

Platelets, alcohol consumption, and onset of brain infarction.

Previous investigations have suggested that recurrent rebound thrombocytosis after alcohol misuse may be a factor in the pathogenesis of thromboembolic disease. Alcohol consumption, platelet count, and platelet function were examined among patients of working age with brain infarction. Platelet count and risk factors for stroke were studied in 426 stroke patients and 157 control patients in hospital. The measures were platelet count obtained within four days after the stroke onset, in vitro adenosine diphosphate induced platelet aggregation, associated thromboxane B2 formation, and urinary excretion of 11-dehydrothromboxane B2. After adjustment for sex, age, cardiac disease, diabetes, and alcohol intake, hypertension (OR 3.4, 95% confidence interval (95% CI) 2.0-6.0) and current smoking (OR 2.1, 95% CI 1.4-3.3) were associated with an increased risk for brain infarction. Platelet count shortly after the onset of disease was higher in the stroke patients than in the controls (OR 1.05/10(10)/1 platelets; 95% CI 1.02-1.09). The patients with brain infarction who were heavy alcohol drinkers (n = 144) showed both thrombocytosis (OR 2.30, 95% CI 0.82-6.44) and thrombocytopenia (OR 3.20, 95% CI 1.19 to 8.59) more often at the onset of the stroke than the other patients with brain infarction. The thromboxane variables showed inconsistent associations with the onset of stroke. There was no consistent platelet abnormality among alcohol misusers at the onset of ischaemic brain infarction. Alcohol induced thrombocytopenia and rebound thrombocytosis were both often seen at the onset of brain infarction in patients who were heavy alcohol drinkers. Therefore, other mechanisms which could contribute to the high frequency of recurrences of ischaemic stroke among heavy drinkers should be investigated.

Hemostatic alterations in cancer patients.

Nearly all patients with cancer manifest laboratory evidence of hypercoagulability and some develop clinical thromboembolic disease (TED). Routine laboratory studies of blood coagulation have been performed in several large, prospective trials of the use of anticoagulant drugs in cancer treatment. The results of these studies, as well as data from several smaller studies of more sensitive tests of hypercoagulability [e.g. fibrinopeptide A (FPA); thrombin-antithrombin (TAT) complexes; prothrombin fragment F1 + 2)], indicate that the levels of some clotting proteins parallel disease activity. However, no studies of sound methodologic design have yet been performed to indicate that any of these tests of blood coagulation can serve as adequate predictors of TED in patients with cancer. In addition to the important role played by tumor-related procoagulants, several other mechanisms may be involved in the pathogenesis of thromboembolic events in patients with cancer, including stasis and endothelial damage. Considerable variability in the relative importance of these mechanisms in the pathogenesis of TED may exist among patients with different types of cancer. The risk for TED associated with surgical procedures in cancer patients is substantial and prophylactic antithrombotic therapy should be considered for most of these patients. Chemotherapy and hormonal therapy of cancer probably increases the likelihood of TED, particularly in those subjects with indwelling venous catheters. This risk has been particularly well-studied in patients with breast cancer treated with tamoxifen plus cytotoxic drugs. The pathogenic mechanisms may be complex but vascular injury is likely as a proximate cause of venous access catheter thrombosis and can be prevented with low dose coumadin therapy. The utility of low dose coumadin anticoagulation in reducing the risk for TED during breast cancer treatment is unknown but is currently being tested in a large, multiinstitutional study. Since chronic coumadin anticoagulation of cancer patients, and single pulse dose heparin prior to intravenous chemotherapy, both prevent thrombin generation, these agents may be of use in reducing the risk of chemotherapy-associated thrombosis. Prophylactic anticoagulation should be considered for high risk patients.

REBOUND THROMBOCYTOSIS AFTER ALCOHOL ABUSE: A POSSIBLE FACTOR IN THE PATHOGENESIS OF THROMBOEMBOLIC DISEASE

Five alcoholic patients had rebound thrombocytosis after withdrawal of alcohol. This rebound thrombocytosis was not always preceded by thrombocytopenia at admission. Two patients had a history of unexplained recurrent venous thrombosis and recurrent pulmonary embolism. It is suggested that recurrent rebound thrombocytosis after alcohol abuse can be a factor in the pathogenesis of thromboembolic disease in some patients.

Thromboembolic disease: prophylaxis and treatment.

Thromboembolic disease ranks among the most dangerous and common complication in the postoperative or post-traumatic patient. As previously mentioned, the incidence is increasing and fatalities from this complication have also risen substantially. The pathogenesis of thromboembolic disease and the predictability of its occurrence remain elusive. Based upon evidence suggesting that the thrombotic process may begin during surgery, greater attention should be given to the use of prophylactic agents before as well as during the operative procedure. The search continues for a safe, oral agent uniformly effective in preventing thromboembolism.