Markers of coagulation activation, endothelial stimulation and inflammation in patients with peripheral arterial disease

OBJECTIVES

Patients with peripheral arterial disease have a significantly increased risk of cardiovascular and cerebrovascular mortality. Studies have shown that some haemostatic and inflammatory markers are elevated in these patients but the effect of the severity of the disease has not been fully documented. The aim of this study was to assess the level of coagulation activation, endothelial stimulation and inflammation in patients with claudication and critical limb ischaemia (CLI) compared to healthy controls.

DESIGN AND METHODS

A prospective observational study was conducted amongst 202 subjects: 132 claudicants, 30 patients with critical ischaemia, and 40 controls. D-dimer (DD) and thrombin-antithrombin III (TAT) levels measured using ELISA as markers of coagulation activation. von Willebrand factor (vWF) and high-sensitivity C-reactive protein (CRP) levels were measured as markers of endothelial and inflammatory stimulation.

RESULTS

vWF and CRP levels were significantly higher in patients with intermittent claudication (1.9 U/ml, range 0.78-4.05; p < 0.001; 3.4 mg/l, range 0.15-24; p > 0.001, respectively) and critical ischaemia (2.36 U/ml; range 1.03-5.69; p < 0.001; 7.17 mg/ml, range 0.15-174; p < 0.001, respectively) compared to controls (1.28 U/ml, range 0.62-3.13; 1.04, range 0.15-7.59 mg/l). DD was also significantly higher in claudicants (48.6 microg/ml; range 2-1741; p < 0.001) and in patients with CLI (61.1 microg/ml, range 3.65-1963; p < 0.001) compared to controls (26.1 microg/ml, range 9.65-203.1). TAT levels were significantly higher in CLI (3.14 mg/l, range 2.09-58.11), compared to controls (2.36 mg/l, range 1.49-7.38; p = 0.004). Patients with CLI had significantly higher levels of CRP, vWF, and TAT than claudicants.

CONCLUSIONS

Coagulation activation and endothelial stimulation are significantly increased in patients with peripheral arterial disease compared to healthy controls. Coagulation and endothelial activation increases with the severity of the arterial disease.

The procoagulant potential of environmental particles (PM10)

BACKGROUND AND AIMS

Epidemiology studies have shown that cardiovascular (CV) disease is primarily responsible for the mortality associated with increased pulmonary environmental particle (PM10) exposure. The mechanisms involved in PM10 mediated CV effects are unknown although changes in plasma viscosity and in the homoeostasis of blood coagulation have been implicated. It was hypothesised that PM10 exposure would result in an inflammatory response and enhance the activation of the extrinsic coagulation mechanisms in pulmonary and vascular cells in culture.

METHODS

Primary human monocyte derived macrophages and human umbilical cord vein endothelial, human alveolar type II epithelial (A549), and human bronchial epithelial (16HBE) cells were tested for their inflammatory and procoagulant response to PM10 exposure. IL-8, tissue factor (TF), and tissue plasminogen activator (tPA) gene expression and protein release, and coagulation enhancing ability of culture media were determined 6 and 24 hours following exposure.

RESULTS

The culture media from macrophages and 16HBE bronchial epithelial cells, but not A549 cells, exposed to PM10 had an enhanced ability to cause clotting. Furthermore, H2O2 also increased the clotting activity. Apoptosis was significantly increased in macrophages exposed to PM10 and LPS as shown by annexin V binding. TF gene expression was enhanced in macrophages exposed to PM10, and HUVEC tissue factor and tPA gene and protein expression were inhibited.

CONCLUSIONS

These data indicate that PM10 has the ability to alter macrophage, epithelial, and endothelial cell function to favour blood coagulation via activation of the extrinsic pathway and inhibition of fibrinolysis pathways.

Polymorphonuclear leukocytes from patients with severe sepsis have lost the ability to degrade fibrin via u-PA

Fibrin persistence in the vasculature is an important complication of sepsis that can often lead to mortality. We have previously established that polymorphonuclear leukocytes (PMN) from healthy individuals have the capacity to degrade fibrin via urokinase-type plasminogen activator (u-PA). We have also demonstrated an increase in u-PA antigen in the plasma of patients suffering from septic shock. In this study, we investigate the hypothesis that PMN from patients with sepsis have lost their fibrinolytic ability and that this might contribute to the persistence of fibrin deposits. We show here that PMN from these patients do not express any u-PA activity, despite retaining some u-PA antigen. Additionally, thrombi prepared from the whole blood of the patients exhibit reduced endogenous lysis compared with those from healthy individuals. These data indicate that loss of fibrinolytic activity from PMN may be a contributing factor in fibrin persistence in the microvasculature in sepsis.

Establishment and characterization of a new leukaemic T-cell line (Peer) with an unusual phenotype

We report the isolation and establishment in continuous culture of a human lymphoid cell line (Peer) from a case of T-leukemia. The Peer cell line lacks some typical cell-surface properties of T cells, namely sheep erythrocyte rosette formation and reactivity with two anti-T-cell sera, but has focal acid phosphatase and does express two other T-cell antigens, one defined by a monoclonal antibody, the other related to a T-cell subset (TH2). The cells are negative for B-cell markers (SmIg or cytoplasmic mu Fcgamma and C3 receptors, mouse erythrocyte rosettes) and EBV (EBNA). In addition, the Peer cell does not possess the typical phenotypic markers of "non-B, non-T" leukemia: cALL and Ia-like antigens, and the cytoplasmic hexosaminidase isoenzyme I, but is positive for terminal deoxynucleotidyl transferase by enzymatic and immunofluorescent criteria. The cell line requires exogenous L-asparagine for adequate growth in culture, a property known to be characteristic of certain T cells but not of B cells. The Peer cell line appears to have a maturation arrest at a developmental stage intermediate between the cortical thymocyte and a mature T-cell subset and to have lost some T-cell differentiation features.

Rare case of heart failure caused by compression of the left atrium by a thoracic aortic aneurysm

A 61 year old patient was found to have an aneurysm extending from the aortic root to the suprarenal region. He underwent first stage surgery with aortic root and arch replacement, prosthetic aortic valve replacement, and coronary artery bypass grafting. Four weeks later, he presented with breathlessness and signs of heart failure and pleural effusion. Computed tomography showed that the left atrium was compressed between the aortic aneurysm posteriorly and the left ventricle and sternum anteriorly. Obstruction of the superior vena cava, bronchus, oesophagus, and rarely right atrium by an aortic aneurysm has been described before but presentation with left atrial compression has not been reported.

Platelet activation is increased in peripheral arterial disease

OBJECTIVE

Platelet activation was assessed in patients with peripheral arterial disease compared with healthy control subjects.

METHODS

This prospective comparative study included 100 subjects: 40 consecutive patients with intermittent claudication, 20 consecutive patients with critical ischemia and tissue loss, and 40 healthy control subjects. Whole blood flow cytometric analysis was performed to determine resting and stimulated platelet P-selectin expression and resting and stimulated platelet fibrinogen binding. Results are presented as platelet percentage and also as mean fluorescence intensity.

RESULTS

P-selectin expression was significantly increased in patients with intermittent claudication (median, 0.85%; range, 0.31%-4.77%; P =.023) and critical ischemia (median, 1.11%; range, 0.2%-3.26%; P =.028) compared with control subjects (median, 0.59%; range, 0.16%-4.58%). The percentage of platelets binding fibrinogen was also significantly higher in patients with intermittent claudication (median, 2.89%; range, 1.08%-9.59%; P <.001) compared with control subjects (median, 1.57%; range, 0.17%-10.7%). There was no significant difference in percentage of platelet fibrinogen binding between control subjects and patients with critical ischemia. Fibrinogen binding by stimulated platelets was significantly diminished in patients with critical limb ischemia compared with control subjects (67.2% vs 77.9%; P =.006).

CONCLUSIONS

Platelet activation is increased in patients with peripheral arterial disease, suggesting an underlying prothrombotic state. Platelets from patients with critical limb ischemia are less responsive to in vitro stimulation.

Exposure to power frequency electric fields and the risk of childhood cancer in the UK

The United Kingdom Childhood Cancer Study, a population-based case-control study covering the whole of Great Britain, incorporated a pilot study measuring electric fields. Measurements were made in the homes of 473 children who were diagnosed with a malignant neoplasm between 1992 and 1996 and who were aged 0-14 at diagnosis, together with 453 controls matched on age, sex and geographical location. Exposure assessments comprised resultant spot measurements in the child's bedroom and the family living-room. Temporal stability of bedroom fields was investigated through continuous logging of the 48-h vertical component at the child's bedside supported by repeat spot measurements. The principal exposure metric used was the mean of the pillow and bed centre measurements. For the 273 cases and 276 controls with fully validated measures, comparing those with a measured electric field exposure >/=20 V m(-1) to those in a reference category of exposure <10 V m(-1), odds ratios of 1.31 (95% confidence interval 0.68-2.54) for acute lymphoblastic leukaemia, 1.32 (95% confidence interval 0.73-2.39) for total leukaemia, 2.12 (95% confidence interval 0.78-5.78) for central nervous system cancers and 1.26 (95% confidence interval 0.77-2.07) for all malignancies were obtained. When considering the 426 cases and 419 controls with no invalid measures, the corresponding odds ratios were 0.86 (95% confidence interval 0.49-1.51) for acute lymphoblastic leukaemia, 0.93 (95% confidence interval 0.56-1.54) for total leukaemia, 1.43 (95% confidence interval 0.68-3.02) for central nervous system cancers and 0.90 (95% confidence interval 0.59-1.35) for all malignancies. With exposure modelled as a continuous variable, odds ratios for an increase in the principal metric of 10 V m(-1) were close to unity for all disease categories, never differing significantly from one.

Upgrading Athabasca Tar Sand Using Toe-to-Heel Air Injection

Abstract

The unique operation of the THAI (Toe-to-Heel Air Injection) process, enables very high oil recovery and substantial in situ upgrading. Both thermal upgrading (non-catalytic) and also catalytic upgrading, in which a catalyst is emplaced along the horizontal producer well, were investigated. 3D physical model experiments were conducted on virgin Athabasca tar sand bitumen to investigate dry and wet combustion performance. These results were compared against those from a steamflood test, which was subsequently followed by air injection. Excellent ignition, very stable combustion propagation and thermal upgrading of nearly 10 ° API were achieved using Athabasca tar sand. Additional upgrading was achieved using an in situ catalyst. THAI has the extra advantage that some hydrogen is generated in situ, providing further significant upgrading via hydroconversion. There are also substantial environmental benefits because of the large reductions in sulphur and heavy metals in the produced oil. Furthermore, oil is produced without "displacement delay," immediately ahead of the combustion front. The oil recovery using THAI was greater than 75% OOIP.

Introduction

The world's conventional crude oil production is expected to reach its peak in the second decade of this century and enter a permanent decline phase(1). The composition of the oil barrel is getting heavier, and diluent blending "stop-gaps," assisted by very limited coker upgrading capacity will, eventually, be insufficient to cope with the increasing demand for light oil. Historically, heavy oil trades at a substantial discount to that of premium light crude oil. Therefore, it has lower economic value and also market potential, unless new technology is developed to upgrade it to lighter oil, in an economic manner.

The Athabasca Tar Sand deposit of northeastern Alberta, Canada, is one of the largest reserves of bitumen in the world. These are estimated to be 212.9 ??109 m3 (1,339 ?109 bbl)(2). Although about 10% of the bitumen reserves are mineable, the rest of the Athabasca Tar Sands have to be exploited by in situ recovery technology. A number of in situ oil recovery methods, such as steam assisted gravity drainage (SAGD)(3) and in situ combustion (ISC)(4, 5), have been extensively studied, both in the laboratory and in field tests.

In situ combustion (ISC) is a thermal EOR method, in which a small fraction of the oil (or coke) in the oil layer is burned in order to mobilize the unburned fraction. Due to the strong exothermic oxidation reactions between hydrocarbon (or coke) and oxygen, the temperature of the oil-bearing matrix in the combustion zone is 500 to 700 °C, which is much higher than in steam flood processes (150 to 250 °C). High temperatures are very favourable for tar sands and heavy oil reservoirs, because not only is the oil viscosity reduced by several orders of magnitude, but the heavy residue is also thermally cracked to lighter compounds.

Prothrombotic genotypes are not associated with pre-eclampsia and gestational hypertension: results from a large population-based study and systematic review

DNA samples collected as part of a large population-based case-control study were genotyped to examine the associations of five prothrombotic gene polymorphisms with pre-eclampsia (PE) and gestational hypertension (GH). The polymorphisms studied were: G1691A in Factor V (Factor V Leiden; FVL), prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, plasminogen activator inhibitor-1 4G/5G and the platelet collagen receptor alpha2beta1 C807T. A group of 404 women who developed PE were retrospectively compared with 303 women with GH and 164 control women. The frequency of genotypes did not differ significantly between cases of PE or GH and controls for any of the five polymorphisms studied. We conclude that these prothrombotic genotypes are not associated with the development of PE or GH in our population. The systematic review supports our conclusion, for all but cases of severe disease. which appear to be associated with FVL and, to a lesser extent, MTHFR C677T. There is little value in antenatal screening for prothrombotic polymorphisms to predict the development of pre-eclampsia or gestational hypertension.

Aspirin dilemma. Remodelling the hypothesis from a fertility perspective

Many clinical trials in obstetrics have failed to demonstrate improved outcomes with low-dose aspirin. This is not entirely surprising as prescribing aspirin for compromised tissue perfusion without insight into underlying pathology inevitably leads to suboptimal outcomes. We argue that a mismatch between the aspirin dose and the underlying pathology of altered tissue perfusion is the key factor to this failure. Based on this groundwork, we address the question of how best to optimize the dose of aspirin for use in fertility management, by providing examples from the assisted conception and recurrent miscarriage settings.

Rare acquired bleeding disorders

Accurate diagnosis of the cause of bleeding is a prerequisite for determination of the optimal therapeutic response. Clinicians are generally aware of the more prevalent hemorrhagic syndromes but some rare acquired conditions are also of importance. In many of these, inhibitors of coagulation factors or of platelet adhesion/aggregation cause bleeding. These inhibitors are generally, but not always, immunoglobulins. In this review, the less common inhibitors of coagulation and hemostasis, as well as some important but rare nutritional, iatrogenic and disease associated hemorrhagic disorders, are described.

GPHN, a novel partner gene fused to MLL in a leukemia with t(11;14)(q23;q24)

We report a novel MLL-associated chromosome translocation t(11;14)(q23;q24) in a child who showed signs of acute undifferentiated leukemia 3 years after intensive chemotherapy that included the topoisomerase-II inhibitor VP 16. Screening of a cDNA library of the patient's leukemic cells showed a novel fusion transcript between MLL and the Gephyrin (GPHN) gene on 14q24. The resulting MLL-GPHN fusion gene encodes MLL AT hook motifs and a DNA methyltransferase homology domain fused to the C-terminal half of Gephyrin, including a presumed tubulin binding site and a domain homologous to the Escherichia coli molybdenum cofactor biosynthesis protein MoeA. Genomic breakpoint analysis showed potential in vitro topoisomerase-II DNA-binding sites spanning the breakpoints in both MLL and GPHN but no flanking sequences that might mediate homologous recombination. This suggests that MLL-GPHN may have been generated by VP 16/topoisomerase-II-induced DNA double-strand breaks, followed by error-prone DNA repair via non-homologous end joining. Gephyrin was originally identified as a submembraneous scaffold protein that anchors and immobilizes postsynaptic membrane neurotransmitter receptors to underlying cytoskeletal elements. It also is reported to bind to phosphatidylinositol 3,4,5-triphosphate binding proteins involved in actin dynamics and downstream signaling and interacts with ATM-related family member RAFT1. Gephyrin domains in the chimeric protein therefore could contribute novel signal sequences or might modify MLL activity by oligomerization or intracellular redistribution.

Thrombin-induced activation of RhoA in platelet shape change

Thrombin-induced activation of RhoA and its involvement in the regulation of myosin II light chain(20) phosphorylation (MLC-P) in alpha-toxin permeabilized platelets was investigated. Permeabilized platelets, expressing normal levels of P-selectin, displayed a Ca(2+)-dependent increase in shape change and MLC-P. Thrombin activated RhoA as measured by a rhotekin-binding assay within 30 s of stimulation under conditions of constant [Ca(2+)](i). Under the same conditions and timecourse, thrombin or GTPgammaS induced an increase in MLC-P and platelet shape change which was not dependent on an increase in [Ca(2+)](i). The thrombin- and GTPgammaS-induced MLC-P in constant [Ca(2+)](i) was inhibited by the addition of Y27632, a Rho-kinase inhibitor. This study directly demonstrates that thrombin can activate RhoA in platelets in a timecourse compatible with a role in increasing MLC-P and shape change (not involving an increase in [Ca(2+)](i)). This is also Rho-kinase-dependent.

The effects of treatment with alpha-lipoic acid or evening primrose oil on vascular hemostatic and lipid risk factors, blood flow, and peripheral nerve conduction in the streptozotocin-diabetic rat

Oxidative stress and defective fatty acid metabolism in diabetes may lead to impaired nerve perfusion and contribute to the development of peripheral neuropathy. We studied the effects of 2-week treatments with evening primrose oil (EPO; n = 16) or the antioxidant alpha-lipoic acid (ALA; n = 16) on endoneurial blood flow, nerve conduction parameters, lipids, coagulation, and endothelial factors, in rats with streptozotocin-induced diabetes. Compared with their nondiabetic littermates, untreated diabetic rats had impaired sciatic motor and saphenous sensory nerve-conduction velocity (NCV; P <.001), reduced endoneurial blood flow (P <.001), and increased serum triglycerides (P <.01), cholesterol (P < 0.01), plasma factor VII (P <.0001), and von Willebrand factor (vWF; P <.0001). Plasma fibrinogen and serum high-density lipoprotein concentrations were not significantly different. Treatment with either ALA or EPO effectively corrected the deficits in NCV and endoneurial blood flow. ALA was associated with marked and statistically significant decreases in fibrinogen, factor VII, vWF, and triglycerides (P <.01, paired t tests before v after treatment). In contrast, EPO was associated with significant (P <.05) increases in fibrinogen, factor VII, vWF, triglycerides, and cholesterol and a significant decrease in high-density lipoprotein. Changes in levels of coagulation factors and lipids, qualitatively similar to those found with EPO, were obtained with a diet containing sunflower oil (to control for calorific and lipid content) or with a normal diet alone. Blood glucose and hematocrit levels were not significantly altered by treatments. These data suggest that although both ALA and EPO improve blood flow and nerve function, their actions on vascular factors differ. The marked effects of ALA in lowering lipid and hemostatic risk factors for cardiovascular disease indicate potential antithrombotic and antiatherosclerotic actions that could be of benefit in human diabetes and merit further study.

Antiphospholipid syndrome: state of the art with emphasis on laboratory evaluation

Antiphospholipid antibodies (aPLs) are associated with arterial and venous thrombosis, recurrent pregnancy loss and thrombocytopenia. Although aPLs have not yet been conclusively shown to be causal in thrombosis and miscarriage, they are useful laboratory markers for the antiphospholipid syndrome (APS). The syndrome can complicate another autoimmune disease, most commonly systemic lupus erythematosus, but more often occurs alone -- primary APS. Identification of the syndrome is clinically important because of the risk of recurrent thrombosis and the need for antithrombotic therapy in many cases. Diagnosis and treatment of APS represent significant challenges, however, owing to the protean clinical manifestations and associations, limitations of currently available laboratory tests for aPLs, and the lack of clear evidence-based guidance on optimal management.

Characterization of germline TP53 splicing mutations and their genetic and functional analysis

Germline TP53 splicing mutations have been described infrequently (>2%) in the literature, however in a series of 40 patients and families identified by our group in which there are germline TP53 mutations, seven affect splicing (18%). The low figure reported in the literature might reflect the method of mutation detection, which in many studies does not include all splice junctions. These data indicate that a significant proportion of TP53 germline mutations are currently unrecognized. We have carried out detailed studies of the effects of the different mutations on splicing, and see distinct variations in the effects of the same mutation in different patients. Furthermore we have identified the usage of a non-consensus splice donor site in four families with an intron 4 splice donor mutation.

No excess of factor V:Q506 genotype but high prevalence of anticardiolipin antibodies without antiendothelial cell antibodies in retinal vein occlusion in young patients

Factor V:Q506 (factor V Leiden) is associated with venous thrombosis and has been reported to be a risk factor for retinal vein occlusion (RVO). Anticardiolipin antibodies (ACA), also associated with RVO, are a marker for the prothrombotic condition antiphospholipid syndrome, in which antiendothelial antibodies (AECA) are also frequently present. This study reviewed 45 younger patients <or=55 years old (21 with branch, 22 with central and 2 with hemispheric RVO) to examine: (1) the rôle of factor V:Q506 in the pathogenesis of RVO, and (2) the prevalence and titre of ACA and AECA in this group. No patient had the factor V:Q506 mutation indicating no increase in frequency above background. Our data suggest that primary screening for factor V:Q506 is not indicated for young patients with RVO who do not have historical evidence suggesting familial thrombophilia. Twenty-nine patients had low-titre ACA (>10 GPL units); in 6 of these, the titre was >20 GPL units (population reference range = 0-10 GPL units). No patient had antiendothelial cell reactivity. The low-titre ACA may therefore represent a non-specific response to vascular injury.