Vascular-bed--specific hemostasis and hypercoagulable states

Heterogeneity in the penumbra

Original experimental studies in nonhuman primate models of focal ischemia showed flow-related changes in evoked potentials that suggested a circumferential zone of low regional cerebral blood flow with normal K(+) homeostasis, around a core of permanent injury in the striatum or the cortex. This became the basis for the definition of the ischemic penumbra. Imaging techniques of the time suggested a homogeneous core of injury, while positing a surrounding 'penumbral' region that could be salvaged. However, both molecular studies and observations of vascular integrity indicate a more complex and dynamic situation in the ischemic core that also changes with time. The microvascular, cellular, and molecular events in the acute setting are compatible with heterogeneity of the injury within the injury center, which at early time points can be described as multiple 'mini-cores' associated with multiple 'mini-penumbras'. These observations suggest the progression of injury from many small foci to a homogeneous defect over time after the onset of ischemia. Recent observations with updated imaging techniques and data processing support these dynamic changes within the core and the penumbra in humans following focal ischemia.

Coagulation biomarkers in critically ill patients

This article discusses coagulation biomarkers in critically ill patients where coagulation abnormalities occur frequently and may have a major impact on the outcome. An adequate explanation for the cause is important, since many underlying disorders may require specific treatment and supportive therapy directed at the underlying condition. Deficiencies in platelets and coagulation factors in bleeding patients or patients at risk for bleeding can be achieved by transfusion of platelet concentrate or plasma products, respectively. Prohemostatic treatment may be beneficial in case of severe bleeding, whereas restoring physiological anticoagulant pathways may be helpful in patients with sepsis and disseminated intravascular coagulation.

Vascular changes, cardiovascular disease and obstructive sleep apnea

Vascular changes related to obstructive sleep apnea (OSA) can lead to chronic cardiovascular consequences such as hypertension. The cardiovascular consequences are owing to nocturnal perturbations related to intrathoracic pressure changes, intermittent hypoxia, sympathetic neural activation, endothelial dysfunction, oxidative stress and systemic inflammation. Intermittent hypoxia due to sleep-related events in OSA activates the renin-angiotensin system and increases the levels of endothelin-1. Intermittent hypoxia also results in oxidative stress, as evidenced by elevated levels of xanthine oxidoreductase, lipid peroxidation and the presence of reactive oxygen species. There is also evidence for a decrease in antioxidant capacity. Patients with OSA may have endothelial dysfunction that resolves with continuous positive airway pressure. OSA is a state of inflammation as evidenced by elevated levels of C-reactive protein, IL-6, NF-κB, TNF-α, ICAM-1, VCAM-1 and E-selectin. This may suggest that OSA is a predisposing factor for atherogenesis. This article will discuss the role of nocturnal perturbations consequent to OSA resulting in endothelial dysfunction, oxidative stress, and inflammation and how they may subsequently play a causative role in cardiovascular disorders.

Systemic versus localized coagulation activation contributing to organ failure in critically ill patients

In the pathogenesis of sepsis, inflammation and coagulation play a pivotal role. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may not only be relevant for vascular atherothrombotic disease in general but has in certain clinical settings considerable consequences, for example in the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Pro-inflammatory cytokines and other mediators are capable of activating the coagulation system and downregulating important physiological anticoagulant pathways. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by physiological anticoagulant mechanisms and endogenous fibrinolysis. Interestingly, apart from the overall systemic responses, a differential local response in various vascular beds related to specific organs may occur.

Imaging and interventions in Budd-Chiari syndrome

Budd-Chiari syndrome (BCS) consists of a group of disorders with obstruction of hepatic venous outflow leading to increased hepatic sinusoidal pressure and portal hypertension. Clinically, two forms of disease (acute and chronic) are recognized. Mostly the patients present with ascites, hepatomegaly, and portal hypertension. In acute disease the liver is enlarged with thrombosed hepatic veins (HV) and ascites, whereas in the chronic form of the disease there may be membranous occlusion of HV and/or the inferior vena cava (IVC), or there may be short or long segment fibrotic constriction of HV or the suprahepatic IVC. Due to advances in radiological interventional techniques and hardware, there have been changes in the management protocol of BCS with surgery being offered to patients not suitable for radiological interventions or having acute liver failure requiring liver transplantation. The present article gives an insight into various imaging findings and interventional techniques employed in the management of BCS.

Budd-Chiari syndrome in a patient with ulcerative colitis and no inherited coagulopathy

We report a case of 27 year old female patient who was admitted to the hospital with an acute flare up of ulcerative colitis. The patient presented with complaints of persistent abdominal pain and bloody diarrhea despite aggressive therapy for her ulcerative colitis. A CT scan of the abdomen on admission revealed hepatic vein thrombosis, suggesting a diagnosis of Budd-Chiari syndrome. Significantly, an associated thrombosis of the inferior mesenteric vein was also detected. Based on imaging data and clinical assessment, the patient was started on anticoagulation therapy and an extensive work-up for hypercoagulability was initiated. Up to the time of publication, no significant findings suggesting this patient has an underlying coagulation disorder have been found. Based on our search of PUBMED, this report is one of only five reported adult cases of Budd-Chiari Syndrome associated with ulcerative colitis in the English literature in living patients without evidence of a co-existing coagulation disorder. This case highlights the potential for thrombosis at unusual sites in ulcerative colitis patients even in the absence of classical coagulation abnormalities. In addition to the case presented, we provide a brief review of previously reported cases of Budd-Chiari Syndrome occurring in patients with inflammatory bowel disease.

Peripheral artery disease, biomarkers, and darapladib

OBJECTIVE

Subjects with peripheral artery disease (PAD) are at increased risk of cardiovascular morbidity and mortality, perhaps in part, related to increased levels of inflammation, platelet activity, and lipids. We therefore sought to investigate the relationship between PAD and levels of inflammatory, platelet, and lipid biomarkers and the treatment effect of darapladib, a novel lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) inhibitor.

METHODS

This is a post hoc analysis of the 959 patients with coronary disease or their risk equivalent receiving atorvastatin who were randomized to receive darapladib or placebo to examine the effects of an Lp-PLA(2) inhibitor on the biomarkers of cardiovascular risk. We conducted an exploratory analysis evaluating the levels of biomarkers in subjects with PAD (n = 172) compared with those without PAD (n = 787).

RESULTS

After adjustment for age, sex, smoking, body mass index, and diabetes, subjects with PAD had greater levels of matrix metalloproteinase-9 (between group comparisons 22%, 95% confidence interval [10-31], P < .01), myeloperoxidase (12% [2-20], P = .01), interleukin-6 (13% [4-21], P = .01), adiponectin (17% [7-26], P < .01), intercellular adhesion molecule-1 (7% [2-11], P < .01), osteoprotegrin (6% [1-10], P = .02), CD40 ligand (15% [1-28], P = .04), high-sensitivity C-reactive protein (17% [1-31], P = .04), and triglycerides (11% [0.2-21], P = .05). No significant difference was detected for Lp-PLA(2) activity, P-selectin, urinary 11-dehydrothroboxane B2, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol between subjects with and without PAD. Darapladib produced highly significant inhibition of Lp-PLA(2) activity when compared with placebo at weeks 4 and 12 (P < .01) in patients with and without PAD.

CONCLUSIONS

Subjects with PAD had elevated levels of matrix metalloproteinase-9, myeloperoxidase, interleukin-6, adiponectin, intercellular adhesion molecule-1, osteoprotegrin, CD40 ligand, high-sensitivity C-reactive protein, and triglycerides compared with those without PAD. Darapladib, a novel Lp-PLA(2) inhibitor, was equally effective in reducing Lp-PLA(2) activity levels in subjects with and without PAD.

The endotheliome: a new concept in vascular biology

As the importance of the endothelium is becoming increasingly recognised, additional tools are needed to assess its functions. Separate studies have looked at different aspects of vascular biology primarily focusing on the central role of the endothelium, i.e. secretion/release of molecules in the plasma, physiological action on other cells, and the presence of endothelial cells themselves in the circulation. Targeting and protecting the endothelium is a promising therapeutic strategy for modifying a number of disease processes but 'ideal' methods to monitor this treatment, like many other tools for assessing endothelial activity, remain elusive. We suggest that a broader view of the endothelium is important, and with it the concept of the assessment of overall vascular function, which fuses different aspects of endothelial activity into a unifying concept. In the present document we review the current understanding of endothelial biology and the methods of its assessment, and hypothesise that a more multifactorial approach to the endothelium will be a crucial determinant of outcomes and treatment strategies for different diseases. This we describe as the 'endotheliome'.

Venous thromboembolism following vigorous deep tissue massage

Venous thromboembolism (VTE) is an increasing public health concern, in part because of lack of awareness among patients and physicians. Nonpenetrating trauma to the legs may be an under-recognized potential risk factor for VTE. We report a case of VTE following vigorous deep tissue massage in a previously healthy 67-year-old man with no other identifiable risk factors. The etiology, risk factors, and implications for the prevention and detection of VTE are reviewed. There are few other published reports of VTE associated with massage, but under-reporting seems likely. Vigorous massage or any equivalent trauma to the legs should be considered and evaluated as a possible risk factor for VTE, especially in older adults. Additional research is needed to clarify the risks associated with nonpenetrating trauma to the legs in older adults and other susceptible groups. Improved awareness of VTE, including its risk factors and symptoms, is an urgent priority for more effective prevention, detection, and treatment.

How inflammation modulates central nervous system vessel activation and provides targets for intervention--a personal perspective

I here describe a line of research that grew out of studies of spinal cord-damaging decompression sickness, focused on the blood-endothelial interface, that was influenced by the local Shwartzman phenomenon, addressed innate immune and inflammatory mechanisms, and ultimately arrived at mucosal tolerance approaches to prevent stroke. Intranasal instillation of E-selectin is under development as a novel means of targeting immunomodulation to activating blood vessels within the vascular tree supplying the brain. The goal of this form of focused immunomodulation is to prevent recurrent strokes in patients that have previously suffered transient ischemic attacks or strokes.

Sepsis-associated disseminated intravascular coagulation and thromboembolic disease

Sepsis is almost invariably associated with haemostatic abnormalities ranging from subclinical activation of blood coagulation (hypercoagulability), which may contribute to localized venous thromboembolism, to acute disseminated intravascular coagulation (DIC), characterized by massive thrombin formation and widespread microvascular thrombosis, partly responsible of the multiple organ dysfunction syndrome (MODS), and subsequent consumption of platelets and coagulation proteins causing, in most severe cases, bleeding manifestations. There is general agreement that the key event underlying this life-threatening sepsis complication is the overwhelming inflammatory host response to the infectious agent leading to the overexpression of inflammatory mediators. Mechanistically, the latter, together with the micro-organism and its derivatives, causes DIC by 1) up-regulation of procoagulant molecules, primarily tissue factor (TF), which is produced mainly by stimulated monocytes-macrophages and by specific cells in target tissues; 2) impairment of physiological anticoagulant pathways (antithrombin, protein C pathway, tissue factor pathway inhibitor), which is orchestrated mainly by dysfunctional endothelial cells (ECs); and 3) suppression of fibrinolysis due to increased plasminogen activator inhibitor-1 (PAI-1) by ECs and likely also to thrombin-mediated activation of thrombin-activatable fibrinolysis inhibitor (TAFI). Notably, clotting enzymes non only lead to microvascular thrombosis but can also elicit cellular responses that amplify the inflammatory reactions. Inflammatory mediators can also cause, directly or indirectly, cell apoptosis or necrosis and recent evidence indicates that products released from dead cells, such as nuclear proteins (particularly extracellular histones), are able to propagate further inflammation, coagulation, cell death and MODS. These insights into the pathogenetic mechanisms of DIC and MODS may have important implications for the development of new therapeutic agents that could be potentially useful particularly for the management of severe sepsis.

Migrating venous thrombosis in acute leukemia

We present a 55-year-old man with acute migrating thrombophlebitis and deep vein thrombosis of muscle veins in both calves indicating occurrence of acute myelomonocytic leukemia. Thrombosis of superficial and deep veins of the lower limbs arose in spite of the adequate anticoagulation therapy with warfarin.

Vascular haemostasis

SUMMARY

While the majority of this session will deal with selected inherited vascular abnormalities that may manifest as a haemorrhagic disorder, the initial discussion by Dr Key will focus on the interplay between the vessel wall and components of the coagulation system, with a focus on haemophilia A and B. Although it is generally accepted that physiological haemostasis is triggered by contact of blood with tissue factor (TF), there remains some controversy regarding the cellular origin of TF in vivo. In addition, the initiation and propagation of thrombin generation are highly dependent on the balance of pro- and anticoagulant functions of endothelium, a profile that varies significantly throughout the vasculature. Drs De Paepe and Malfait address heritable collagen disorders such as the Ehlers-Danlos syndromes (EDS), a heterogeneous group of diseases involving the skin, ligaments and joints, blood vessels and internal organs. Most EDS subtypes are caused by mutations in genes encoding fibrillar collagens, or in genes coding for enzymes involved in posttranslational modifications of collagens. Accurate biochemical and molecular testing is now available for most EDS subtypes and can direct genetic counselling and medical management for these disorders. Dr Shovlin reviews recent developments in hereditary haemorrhagic telengiectasia (HHT), a frequently undiagnosed disorder characterized by arteriovenous malformations in multiple organs. These abnormal blood vessels are the result of mutations in one of a number of genes whose protein products influence TGF-beta signalling in vascular endothelial cells. Several HHT management guidelines have been published and are discussed.

Intravascular lymphomatosis and intracerebral haemorrhage

Intravascular lymphomatosis (IVL) is a rare, malignant B- or T-cell lymphoma with remarkable affinity for the endothelial cells of small vessels, particularly within the skin and central nervous system. It is a disease that mimics several neurological disorders, particularly those of cerebrovascular ischemic origin. The prognosis is generally poor, with a rapidly fatal outcome. As a result the diagnosis is often made at post-mortem. We report a rare case of a 73-year-old patient with IVL complicated by intracerebral haemorrhage. In literature two cases of systemic IVL complicated by intracerebral haemorrhage have been reported, but they presented initially with a disseminated intravascular coagulation (DIC). This is the first case of brain IVL complicated by intracerebral haemorrhage not associated to DIC. Increasing awareness of this disease as a differential diagnosis to a common clinical presentation may lead to more opportunities to evaluate new diagnostic and treatment approaches.

Endothelial-derived tissue factor pathway inhibitor regulates arterial thrombosis but is not required for development or hemostasis

The antithrombotic surface of endothelium is regulated in a coordinated manner. Tissue factor pathway inhibitor (TFPI) localized at the endothelial cell surface regulates the production of FXa by inhibiting the TF/VIIa complex. Systemic homozygotic deletion of the first Kunitz (K1) domain of TFPI results in intrauterine lethality in mice. Here we define the cellular sources of TFPI and their role in development, hemostasis, and thrombosis using TFPI conditional knockout mice. We used a Cre-lox strategy and generated mice with a floxed exon 4 (TFPI(Flox)) which encodes for the TFPI-K1 domain. Mice bred into Tie2-Cre and LysM-Cre lines to delete TFPI-K1 in endothelial (TFPI(Tie2)) and myelomonocytic (TFPI(LysM)) cells resulted in viable and fertile offspring. Plasma TFPI activity was reduced in the TFPI(Tie2) (71% ± 0.9%, P < .001) and TFPI(LysM) (19% ± 0.6%, P < .001) compared with TFPI(Flox) littermate controls. Tail and cuticle bleeding were unaffected. However, TFPI(Tie2) mice but not TFPI(LysM) mice had increased ferric chloride-induced arterial thrombosis. Taken together, the data reveal distinct roles for endothelial- and myelomonocytic-derived TFPI.

Effect of the small molecule plasminogen activator inhibitor-1 (PAI-1) inhibitor, PAI-749, in clinical models of fibrinolysis

BACKGROUND

The principal inhibitor of fibrinolysis in vivo is plasminogen activator inhibitor-1 (PAI-1). PAI-749 is a small molecule inhibitor of PAI-1 with proven antithrombotic efficacy in several preclinical models.

OBJECTIVE

To assess the effect of PAI-749, by using an established ex vivo clinical model of thrombosis and a range of complementary in vitro human plasma-based and whole blood-based models of fibrinolysis.

METHODS

In a double-blind, randomized, crossover study, ex vivo thrombus formation was assessed using the Badimon chamber in 12 healthy volunteers during extracorporeal administration of tissue-type plasminogen activator (t-PA) in the presence of PAI-749 or control. t-PA-mediated lysis of plasma clots and of whole blood model thrombi were assessed in vitro. The role of vitronectin was examined by assessing lysis of fibrin clots generated from purified plasma proteins.

RESULTS

There was a dose-dependent reduction in ex vivo thrombus formation by t-PA (P < 0.0001). PAI-749 had no effect on in vitro or ex vivo thrombus formation or fibrinolysis in the presence or absence of t-PA. Inhibition of PAI-1 with a blocking antibody enhanced fibrinolysis in vitro (P < 0.05).

CONCLUSIONS

Despite its efficacy in a purified human system and in preclinical models of thrombosis, the current study suggests that PAI-749 does not affect thrombus formation or fibrinolysis in a range of established human plasma and whole blood-based systems.

Is opium addiction a risk factor for deep vein thrombosis? A case-control study

The objective of the present study was to investigate the association between opioid addiction and deep vein thrombosis (DVT) and whether opioid addiction is a risk factor of DVT. This case-control study was conducted in Kerman, Iran in 2008. The cases were selected among the patients hospitalized because of DVT. The controls were recruited from the same hospital from internal wards. Opioid addiction was investigated by physician's interview based on Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria. Logistic regression modeling was carried out for statistical analysis. The crude odds ratio (OR) of opioid addiction for DVT was 4.25 (95% confidence interval = 2.6-6.9). However, multivariate logistic regression analysis revealed that opioid addiction was not an independent risk factor for DVT, OR 0.56 (0.1-3). The method of opioid usage--oral or inhaled and injected--OR 6.3 (1.41-28.3) and previous surgery in the last 3 months before the study, OR 3.1 (1.36-7), were significant independent risk factors for incidence of DVT. Opioid addiction per se was not a risk factor for DVT, whereas the method of its use especially injection was found to be independent risk factor for DVT. Our results suggested the prophylactic treatment of anticoagulant for intravenous drug abuser is considerable.

Hematological issues in critically ill patients with cancer

Patients with solid and hematologic malignancies presenting with major bleeding or thrombotic complications, potentially life-ending events in a cancer patient's clinical course, usually require admission to an intensive care unit (ICU), making their diagnosis and management even more important for the intensivist. Given the significant advances in the diagnosis and treatment of almost all types of cancers in recent years, the intensivist is likely to encounter an ever-increasing number of cancer patients in the ICU setting with these complications. Abnormal hemostasis can occur as a consequence of both the pathology and treatment of cancer. Because cancer can have multiple effects on hemostatic equilibrium, treatment of these complications can be more complex than in the general population. This article reviews the physiology of coagulation and fibrinolysis, with special attention to those aspects that are most frequently altered in the setting of malignancy. The pathophysiology of bleeding and thrombotic complications specific to critically ill cancer patients are then detailed, and the diagnostic and therapeutic strategies are discussed. Special emphasis is placed on new cancer medications that have an effect on hemostasis, and on novel clotting and anticoagulant agents that are available to the intensivist for the management of these patients.

Dengue virus pathogenesis: an integrated view

Much remains to be learned about the pathogenesis of the different manifestations of dengue virus (DENV) infections in humans. They may range from subclinical infection to dengue fever, dengue hemorrhagic fever (DHF), and eventually dengue shock syndrome (DSS). As both cell tropism and tissue tropism of DENV are considered major determinants in the pathogenesis of dengue, there is a critical need for adequate tropism assays, animal models, and human autopsy data. More than 50 years of research on dengue has resulted in a host of literature, which strongly suggests that the pathogenesis of DHF and DSS involves viral virulence factors and detrimental host responses, collectively resulting in abnormal hemostasis and increased vascular permeability. Differential targeting of specific vascular beds is likely to trigger the localized vascular hyperpermeability underlying DSS. A personalized approach to the study of pathogenesis will elucidate the basis of individual risk for development of DHF and DSS as well as identify the genetic and environmental bases for differences in risk for development of severe disease.

The role of tissue factor and tissue factor pathway inhibitor in health and disease states

OBJECTIVE

To review the veterinary and human literature on the role of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in health and disease states.

DATA SOURCES

Original research articles and scientific reviews from both human and veterinary literature were searched for relevance to TF and TFPI.

HUMAN DATA SYNTHESIS

Interest in both TF and TFPI has grown widely over the last several years. The impact TF plays in coagulation, inflammation, angiogenesis, tumor metastasis, and cellular signaling has become apparent. Treatment with TFPI for severe sepsis has been examined and is still currently under investigation. Inhibition of the TF pathway is being studied as an aid in the treatment of neoplasia. The important physiologic and pathophysiologic role these molecules play has only begun to be understood.

VETERINARY DATA SYNTHESIS

There is a paucity of publications that discuss the importance of TF and TFPI in veterinary medicine. An enhanced understanding of the TF pathway in human medicine, in experimental animal models treating sepsis with TFPI, and in animal models demonstrating the proangiogenic properties of TF provides relevance to veterinary medicine.

CONCLUSION

It is apparent that TF and TFPI are important in health and disease. An enhanced understanding of the physiologic and pathophysiologic roles of these factors provides better insight into coagulation, inflammation, angiogenesis, disseminated intravascular coagulation, and tumor metastasis. This greater understanding may provide for the development of therapeutics for sepsis, disseminated intravascular coagulation, and neoplasia.

Effect of cardiopulmonary bypass on activated partial thromboplastin time waveform analysis, serum procalcitonin and C-reactive protein concentrations

Introduction

Systemic inflammatory response syndrome (SIRS) is a frequent condition after cardiopulmonary bypass (CPB) and makes conventional biological tests fail to detect postoperative sepsis. Biphasic waveform (BPW) analysis is a new biological test derived from activated partial thromboplastin time that has recently been proposed for sepsis diagnosis. The aim of this study was to investigate the accuracy of BPW to detect sepsis after cardiac surgery under CPB.

Methods

We conducted a prospective study in American Society of Anesthesiologists' (ASA) physical status III and IV patients referred for cardiac surgery under CPB. Procalcitonin (PCT) and BPW were recorded before surgery and every day during the first week following surgery. Patients were then divided into three groups: patients presenting no SIRS, patients presenting with non-septic SIRS and patients presenting with sepsis.

Results

Thirty two patients were included. SIRS occurred in 16 patients (50%) including 5 sepsis (16%) and 11 (34%) non-septic SIRS. PCT and BPW were significantly increased in SIRS patients compared to no SIRS patients (0.9 [0.5-2.2] vs. 8.1 [2.0-21.3] ng/l for PCT and 0.10 [0.09-0.14] vs. 0.29 [0.16-0.56] %T/s for BPW; P < 0.05 for both). We observed no difference in peak PCT value between the sepsis group and the non-septic SIRS group (8.4 [7.5-32.2] vs. 7.8 [1.9-17.5] ng/l; P = 0.67). On the other hand, we found that BPW was significantly higher in the sepsis group compared to the non-septic SIRS group (0.57 [0.54-0.78] vs. 0.19 [0.14-0.29] %T/s; P < 0.01). We found that a BPW threshold value of 0.465%T/s was able to discriminate between sepsis and non-septic SIRS groups with a sensitivity of 100% and a specificity of 93% (area under the curve: 0.948 +/- 0.039; P < 0.01). Applying the previously published threshold of 0.25%T/s, we found a sensitivity of 100% and a specificity of 72% to discriminate between these two groups. Neither C-reactive protein (CRP) nor PCT had significant predictive value (area under the curve for CRP was 0.659 +/- 0.142; P = 0.26 and area under the curve for PCT was 0.704 +/- 0.133; P = 0.15).

Conclusions

BPW has potential clinical applications for sepsis diagnosis in the postoperative period following cardiac surgery under CPB.

Diagnostic and interventional radiology for Budd-Chiari syndrome

Budd-Chiari syndrome is a heterogeneous group of disorders characterized by hepatic venous outflow obstruction that involves one or more draining hepatic veins. Its occurrence in populations in the western hemisphere is commonly associated with hypercoagulative states. Clinical manifestations in many cases are nonspecific, and imaging may be critical for early diagnosis of venous obstruction and accurate assessment of the extent of disease. If Budd-Chiari syndrome is not treated promptly and appropriately, the outcome may be dismal. Comprehensive imaging evaluations, in combination with pathologic analyses and clinical testing, are essential for determining the severity of disease, stratifying risk, selecting the appropriate therapy, and objectively assessing the response. The main goal of treatment is to alleviate hepatic congestion, thereby improving hepatocyte function and allowing resolution of portal hypertension. Various medical, endovascular, and surgical treatment options are available. Percutaneous and endovascular procedures, when performed in properly selected patients, may be more effective than medical treatment methods for preserving liver function and arresting disease progression in the long term. In addition, such procedures are associated with lower morbidity and mortality than are open surgical techniques.

Sepsis and septic shock: a history

Infectious disease has been a leading cause of death in humans since the first recorded tabulations. From Hippocrates and Galen, to Lister, Fleming and Semmelweiss, this article reviews the notable historical figures of sepsis research. The early descriptions and theories about the etiology (microbial pathogens), pathogenesis (toxins and mediators), and treatment of sepsis-associated disease are also discussed.

Renal and cardiac endothelial heterogeneity impact acute vascular rejection in pig-to-baboon xenotransplantation

Xenograft outcomes are dictated by xenoantigen expression, for example, Gal alpha1, 3Gal (Gal), but might also depend on differing vascular responses. We investigated whether differential vascular gene expression in kidney and cardiac xenografts correlate with development of thrombotic microangiopathy (TM) and consumptive coagulation (CC). Immunosuppressed baboons underwent miniswine or hDAF pig kidney (n = 6) or heart (n = 7), or Gal-transferase gene-knockout (GalT-KO) (thymo)kidney transplantation (n = 14). Porcine cDNA miniarrays determined donor proinflammatory, apoptosis-related and vascular coagulant/fibrinolytic gene expression at defined time points; validated by mRNA, protein levels and immunopathology. hDAF-transgenic and GalT-KO xenografts, (particularly thymokidneys) exhibited prolonged survival. CC was seen with Gal-expressing porcine kidneys (3 of 6), only 1 of 7 baboons postcardiac xenotransplantation and was infrequent following GalT-KO grafts (1 of 14). Protective-type genes (heme oxygenase-I, superoxide dismutases and CD39) together with von Willebrand factor and P-selectin were upregulated in all renal grafts. Transcriptional responses in Gal-expressing xenografts were comparable to those seen in the infrequent GalT-KO rejection. In cardiac xenografts, fibrin deposition was associated with increased plasminogen activator inhibitor-1 expression establishing that gene expression profiles in renal and cardiac xenografts differ in a quantitative manner. These findings suggest that therapeutic targets may differ for renal and cardiac xenotransplants.

High levels of factor VIII and risk of extra-hepatic portal vein obstruction

BACKGROUND/AIMS

High levels of coagulation factor VIII are a risk factor for lower-limb deep vein thrombosis (DVT). Their role in extra-hepatic portal vein obstruction (EHPVO) is not established.

METHODS

Factor VIII was measured in 85 patients with EHPVO (primary in 58 and complicating liver cirrhosis in 27), in 200 with lower-limb DVT, in 108 with liver cirrhosis without thrombosis and in 200 healthy controls.

RESULTS

Factor VIII levels were significantly higher in patients with primary EHPVO (138 IU/dL, range 86-366), EHPVO and cirrhosis (147 IU/dL, 95-242), lower-limb DVT (140 IU/dL, 64-400) and cirrhosis alone (160 IU/dL, 43-446) than in controls (112 IU/dL, 62-250, p<0.001). When factor VIII exceeded 129 IU/dL (66th percentile), the odds ratios were 10.5 (95%CI 3.3-33.4) for primary EHPVO, 6.0 (1.2-30.7) for EHPVO and cirrhosis, 5.0 (2.6-9.4) for lower-limb DVT. After exclusion of the effect of the acute phase reaction, the odds ratio for primary EHPVO was 4.2 (0.8-22.7), and was 8.7 (0.9-80.5) after exclusion also of patients with chronic myeloproliferative disorders.

CONCLUSIONS

High factor VIII levels are independently associated with an increased risk for EHPVO. The risk of EHPVO increased with increasing factor VIII levels and was only partially dependent on the acute phase reaction.

Major differences in bleeding symptoms between factor VII deficiency and hemophilia B

SUMMARY BACKGROUND

The autosomally-inherited factor VII (FVII) deficiency and X-linked hemophilia B offer an attractive model to investigate whether reduced levels of FVII and FIX, acting in the initiation and amplification of coagulation respectively, influence hemostasis to a different extent in relation to age and bleeding site.

METHODS

Hemophilia B patients (n = 296) and FVII-deficient males (n = 109) were compared for FVII/FIX clotting activity, F7/F9 genotypes and clinical phenotypes in a retrospective, multi-centre, cohort study.

RESULTS

Major clinical differences between diseases were observed. Bleeding occurred earlier in hemophilia B (median age 2.0 years, IR 0.9-5.0) than in FVII deficiency (5.2 years, IR 1.9-15.5) and the bleeding-free survival in FVII deficiency was similar to that observed in 'mild' hemophilia B (P = 0.96). The most frequent disease-presenting symptoms in hemophilia B (hematomas and oral bleeding) differed from those in FVII deficiency (epistaxis and central nervous system bleeding). Differences were confirmed by analysis of FVII-deficient women.

CONCLUSIONS

Our data support the notion that low FVII levels sustain hemostasis better than similarly reduced FIX levels. On the other hand, minute amounts of FVII, differently to FIX, are needed to prevent fatal bleeding, as indicated by the rarity of null mutations and the associated life-threatening symptoms in FVII deficiency, which contributes towards shaping clinical differences between diseases in the lowest factor level range. Differences between diseases are only partially explained by mutational patterns and could pertain to the specific roles of FVII and FIX in coagulation phases and to vascular bed-specific components.

Glucocorticoids in osteonecrosis of the femoral head: a new understanding of the mechanisms of action

Glucocorticoid (GC) usage is the most common non-traumatic cause of osteonecrosis of the femoral head (ON). Despite the strong association of GC with ON, the underlying mechanisms have been unclear. Investigators have proposed both direct and indirect effects of GC on cells. Indirect and direct mechanisms remain intimately related and often result in positive feedback loops to potentiate the disease processes. However, the direct effects, in particular apoptosis, have recently been shown to be increasingly important. Suppression of osteoblast and osteoclast precursor production, increased apoptosis of osteoblasts and osteocytes, prolongation of the lifespan of osteoclasts and apoptosis of endothelial cells (EC) are all direct effects of GC usage. Elevated blood pressure through several pathways may raise the risk of clot formation. High-dose GC also decreases tissue plasminogen activator activity (t-PA) and increases plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels increasing the procoagulant potential of GC. Inhibited angiogenesis, altered bone repair and nitric oxide metabolism can also result. Also, GC treatment modulates other vasoactive mediators such as endothelin-1, noradrenalin and bradykinin. Thus, GCs act as a regulator of local blood flow by modulating vascular responsiveness to vasoactive substances. Vasoconstriction induced in intraosseous femoral head arteries causes femoral head ischemia. GCs also cause ischemia through increased intraosseous pressure, which subsequently decreases the blood flow to the femoral head by apoptosis of ECs as well as elevating the level of adipogenesis and fat hypertrophy in the bone marrow. It is difficult to predict which patients receiving a specific dose of GC will develop ON, indicating individual differences in steroid sensitivity and the potential of additional mechanisms. The textbook model of ON is a multiple hit theory in which, with a greater number of risk factors, the risk of ON increases. While more effort is needed to better comprehend the role of GC in ON, newer data on GC action upon the endothelial cell and the regional endothelial bed dysfunction theory sheds new light on particular GC mechanisms. Better understanding of GC pathomechanisms can lead to better treatment options.

Functional analysis of mutant variants of thrombin-activatable fibrinolysis inhibitor resistant to activation by thrombin or plasmin

BACKGROUND

Thrombin-activatable fibrinolysis inhibitor (TAFI) defines a pathway that functionally links the coagulation and fibrinolytic cascades. TAFI is activated by proteolytic cleavage, a reaction that can be performed by thrombin and plasmin, but most efficiently by thrombin in complex with the endothelial cofactor thrombomodulin (TM). The respective roles of these activators in regulating the TAFI pathway are largely unknown.

OBJECTIVE AND METHODS

In the present study, we constructed and expressed mutant variants of TAFI that have key substitutions in the amino acids surrounding the scissile Arg92-Ala93 bond.

RESULTS AND CONCLUSIONS

We identified variants that showed patterns of resistance to specific activators. For example, the P91S, R92K and S90P variants exhibited specific impairment of activation by thrombin or thrombin-TM, thrombin alone, and thrombin alone or plasmin, respectively. The variants that we tested also showed antifibrinolytic potentials that can be rationalized in terms of which enzymes are capable of activating them. On the other hand, certain predictions from peptide studies of mutations that would be expected to interfere with plasmin cleavage were not satisfied by our data, indicating that protein context, as well as the identity of amino acids at protease cleavage sites, dictates protease specificity.

Trauma-hemorrhagic shock-induced pulmonary epithelial and endothelial cell injury utilizes different programmed cell death signaling pathways

Intestinal ischemia after trauma-hemorrhagic shock (T/HS) results in gut barrier dysfunction and the production/release of biologically active and tissue injurious factors in the mesenteric lymph, which, in turn, causes acute lung injury and a systemic inflammatory state. Since T/HS-induced lung injury is associated with pulmonary endothelial and epithelial cell programmed cell death (PCD) and was abrogated by mesenteric lymph duct ligation, we sought to investigate the cellular pathways involved. Compared with trauma-sham shock (T/SS) rats, a significant increase in caspase-3 and M30 expression was detected in the pulmonary epithelial cells undergoing PCD, whereas apoptosis-inducing factor (AIF), but not caspase-3, was detected in endothelial cells undergoing PCD. This AIF-mediated pulmonary endothelial PCD response was validated in an in situ femoral vein assay where endothelial cells were found to express AIF but not caspase-3. To complement these studies, human umbilical vein endothelial cell (HUVEC), human lung microvascular endothelial cell (HLMEC), and human alveolar type II epithelial cell (A549) lines were used as in vitro models. T/HS lymph induced the nuclear translocation of AIF in HUVEC and HLMEC, and caspase inhibition in these cells did not afford any cytoprotection. For proof of principle, AIF silencing in HUVEC reversed the cytotoxic effects of T/HS on cell viability and DNA fragmentation. In A549 cells, T/HS lymph activated caspase-3-mediated apoptosis, which was partially abrogated by N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). Additionally, T/HS lymph did not cause the nuclear translocation of AIF in A549 cells. Collectively, T/HS-induced pulmonary endothelial PCD occurs via an AIF-dependent caspase-independent pathway, whereas epithelial cells undergo apoptosis by a caspase-dependent pathway.

Pericyte signaling in the neurovascular unit

Brain pericytes are intimately associated with capillary endothelial cells, separated only by basement membrane. Pericyte research has been hampered by absence of pericyte-specific immunochemical markers. The vast array of pericyte functions include contractility, immunologic, migratory, and angiogenic. Pericytes have stem cell potential, contribute to the integrity of the blood-brain barrier, and have a regulatory role for hemostasis in the brain. Improvement in pericyte identification is likely to lead to marked increase in appreciation of the role of pericytes in the neurovascular unit.

Fibrinogen beta-chain tyrosine nitration is a prothrombotic risk factor

Elevated levels of circulating fibrinogen are associated with an increased risk of atherothrombotic diseases although a causative correlation between high levels of fibrinogen and cardiovascular complications has not been established. We hypothesized that a potential mechanism for an increased prothrombotic state is the post-translational modification of fibrinogen by tyrosine nitration. Mass spectrometry identified tyrosine residues 292 and 422 at the carboxyl terminus of the beta-chain as the principal sites of fibrinogen nitration in vivo. Immunoelectron microscopy confirmed the incorporation of nitrated fibrinogen molecules in fibrin fibers. The nitration of fibrinogen in vivo resulted in four distinct functional consequences: increased initial velocity of fibrin clot formation, altered fibrin clot architecture, increased fibrin clot stiffness, and reduced rate of clot lysis. The rate of fibrin clot formation and clot architecture was restored upon depletion of the tyrosine-nitrated fibrinogen molecules. An enhanced response to the knob "B" mimetic peptides Gly-His-Arg-Pro(am) and Ala-His-Arg-Pro(am) suggests that incorporation of nitrated fibrinogen molecules accelerates fibrin lateral aggregation. The data provide a novel biochemical risk factor that could explain epidemiological associations of oxidative stress and inflammation with thrombotic complications.

Recombinant fibrinogenase from Agkistrodon acutus venom protects against sepsis via direct degradation of fibrin and TNF-alpha

Severe sepsis remains a leading cause of death and disability because of less effective therapy available for this disease. A complex interplay between the inflammatory factors and the coagulation pathways seems to be the fundamental mechanisms for the pathogenesis of sepsis. Here we report that recombinant fibrinogenase II (rF II) from Agkistrodon acutus plasmin-independently degraded the thrombi, and inhibited inflammatory responses by direct and specific degradation of tumor necrosis factor alpha (TNF-alpha) induced by lipopolysaccharide (LPS) without showing proteolytic activities on interleukin-1 (IL-1), cluster of differentiation 68 (CD68) and some other serum proteins. We also report that rF II effectively protected against LPS induced sepsis in a rabbit model. Administration of rF II reduced hepatic and renal damage, decreased the levels of alanine aminotransferase (ALT) and blood urea nitrogen (BUN), and increased survival rate in LPS-induced sepsis rabbits. We further confirmed the rescue effect of rF II on severe sepsis in rat caecal ligation and puncture (CLP) model. Our findings suggest that rF II could effectively protect against sepsis via direct degradation of microthrombi and inflammatory factor TNF-alpha as well as provide a novel strategy to develop a single proteinase molecule for targeting the main pathological processes of this disease.

Pathogenic role of antiphospholipid antibodies

The antiphospholipid antibody syndrome (APS) is characterized by recurrent arterial and venous thrombosis and/or pregnancy in association with antiphospholipid (aPL) antibodies. The pathogenic mechanisms in APS that lead to in vivo injury are incompletely understood. Recent evidence suggests that APL antibodies alter regulation of haemostasis and induce activation of complement. We will discuss the current knowledge on how aPL antibodies trigger increased inflammation and enhanced thrombotic tendency, and thereby lead to tissue damage.

Orthostatic hypercoagulability: a novel physiological mechanism to activate the coagulation system

Orthostatic stress causes significant plasma shift and raises transmural pressure in lower extremities, resulting in an increase in endothelial activation and plasma proteins concentrations, possibly including coagulation factors. This may lead to activation of the coagulation system during standing. To test this hypothesis, we recruited 18 healthy volunteers (9 females and 9 males; mean age: 25+/-1.2 years; body mass index: 21.7+/-0.5 kg/m(2)). Hemodynamics, plasma shift (extrapolated from sequential hematocrit concentration), plasma proteins, and coagulation tests, including procoagulants; fibrinogen, factor V, and factor VIII activity; prothrombin fragments 1 and 2; and endothelial activation-related factors (tissue factor and von Willebrand factor), as well as protein C global pathway, were determined at rest supine and at 15 minutes, 30 minutes, and 60 minutes of still standing. Thirty minutes of standing caused a decrease in plasma volume by 12.0+/-0.5% and an increase in plasma protein by 13.0+/-0.7%. Fibrinogen, factor V, and factor VIII activity rose by 12.0+/-1.2%, 13.0+/-1.0%, and 40.0+/-6.0% (P<0.002 for all), respectively. Prothrombin fragments 1 and 2 were elevated by 150.0+/-30.0%. Tissue factor and von Willebrand factor increased by 30.0+/-9.0% and 17.4+/-51.0% (P<0.02 for both), respectively. However, protein C assay results decreased from 0.95+/-0.20 to 0.83+/-0.16 (P<0.001). We hereby introduce a novel physiological mechanism, "orthostatic procoagulation," that should be considered during coagulation tests. Furthermore, it could be extrapolated to the pathophysiology of stasis and venous thromboembolism.

Reduced incidence of ischemic stroke in patients with severe factor XI deficiency

Inherited disorders of hemostasis are natural models for investigating mechanisms of thrombosis and development of antithrombotic therapy. Because mice with total factor XI deficiency are protected against ischemic stroke and do not manifest excessive bleeding, we investigated the incidence of ischemic stroke in patients with severe inherited factor XI deficiency. Incidence of ischemic stroke in 115 patients aged 45 years or more with severe factor XI deficiency (activity less than 15 U/dL) was compared with incidence in the Israeli population as estimated from a stroke survey of 1528 patients. Adjustment for major risk factors of stroke (hypertension, diabetes mellitus, hypercholesterolemia, current smoking) was based on comparison of their prevalence in the stroke survey to an Israeli health survey of 9509 subjects. Incidence of myocardial infarction in the factor XI cohort was also recorded. After adjustment for the 4 major risk factors of ischemic stroke, the expected incidence of ischemic stroke was 8.56 compared with one observed (P = .003). The reduced 1:115 incidence of ischemic stroke contrasted with a 19:115 incidence of myocardial infarction, similar to the expected incidence. Thus, severe factor XI deficiency probably is protective against ischemic stroke but not against acute myocardial infarction.

Combined effect of hemostatic gene polymorphisms and the risk of myocardial infarction in patients with advanced coronary atherosclerosis

Background

Relative little attention has been devoted until now to the combined effects of gene polymorphisms of the hemostatic pathway as risk factors for Myocardial Infarction (MI), the main thrombotic complication of Coronary Artery Disease (CAD). The aim of this study was to evaluate the combined effect of ten common prothrombotic polymorphisms as a determinant of MI.

Methodology/Principal Findings

We studied a total of 804 subjects, 489 of whom with angiographically proven severe CAD, with or without MI (n = 307; n = 182; respectively). An additive model considering ten common polymorphisms [Prothrombin 20210G>A, PAI-1 4G/5G, Fibrinogen β -455G>A, FV Leiden and “R2”, FVII -402G>A and -323 del/ins, Platelet ADP Receptor P2Y12 -744T>C, Platelet Glycoproteins Ia (873G>A), and IIIa (1565T>C)] was tested. The prevalence of MI increased linearly with an increasing number of unfavorable alleles (χ² for trend = 10.68; P = 0.001). In a multiple logistic regression model, the number of unfavorable alleles remained significantly associated with MI after adjustment for classical risk factors. As compared to subjects with 3-7 alleles, those with few (≤2) alleles had a decreased MI risk (OR 0.34, 95%CIs 0.13–0.93), while those with more (≥8) alleles had an increased MI risk (OR 2.49, 95%CIs 1.03–6.01). The number of procoagulant alleles correlated directly (r = 0.49, P = 0.006) with endogenous thrombin potential.

Conclusions

The combination of prothrombotic polymorphisms may help to predict MI in patients with advanced CAD.