Hemostatic Disturbances Research Articles

Bleeding complications: therapeutic strategies in haemostasis

Several haemostyptic agents as well as cellular and plasmatic blood products are available for treatment of bleeding complications. Selective application of these compounds according to the patient’s haemostatic disturbances is superior to standard application of cellular concentrates and fresh frozen plasma. Near‐patient testing of whole blood coagulation and fibrinolysis has been suggested for goal directed therapy. Recent data show reduction of consumption of blood products using algorithms and tailored therapy.

Lonomia obliqua venomous secretion induces human platelet adhesion and aggregation

The caterpillar Lonomia obliqua is a venomous animal that causes numerous accidents, especially in southern Brazil, where it is considered a public health problem. The clinical manifestations include several haemostatic disturbances that lead to a hemorrhagic syndrome. Considering that platelets play a central role in hemostasis, in this work we investigate the effects of L. obliqua venomous secretion upon blood platelets responses in vitro. Results obtained shows that L. obliqua venom directly induces aggregation and ATP secretion in human washed platelets in a dose-dependent manner. Electron microscopy studies clearly showed that the venomous bristle extract was also able to produce direct platelets shape change and adhesion as well as activation and formation of platelet aggregates. Differently from other enzyme inhibitors, the venom-induced platelet aggregation was significatively inhibited by p-bromophenacyl bromide, a specific inhibitor of phospholipases A2. Additional experiments with different pharmacological antagonists indicate that the aggregation response triggered by the venom active components occurs through a calcium-dependent mechanism involving arachidonic acid metabolite(s) of the cyclooxygenase pathway and activation of phosphodiesterase 3A, an enzyme that leads to the consumption of intracellular cAMP content. It was additionally found that L. obliqua-induced platelet aggregation was independent of ADP release. Altogether, these findings are in line with the need for a better understanding of the complex hemorrhagic syndrome resulting from the envenomation caused by L. obliqua caterpillars, and can also give new insights into the management of its clinical profile.

Spontaneous Intraoral Hemorrhage as Manifestation of Thoracoabdominal Aortic Aneurysm-Associated Disseminated Intravascular Coagulation: Case Report and Review

Intraoral bleeding from the gingiva or alveolar mucosa is a common symptom in dental and oral surgery outpatients. The bleeding is relatively easy to control with professional dental treatment, because it is almost always from local causes, such as inflammation or application of extreme external force to the mucosa. Occasionally, persistent or intermittent hemorrhage refractory to treatment indicates a general hemostatic disturbance, including coagulation factor deficiencies, fibrinolytic defects, and platelet or vascular disorders.

Pioglitazone and mechanisms of CV protection

Pioglitazone has diverse multiple effects on metabolic and inflammatory processes that have the potential to influence cardiovascular disease pathophysiology at various points in the disease process, including atherogenesis, plaque inflammation, plaque rupture, haemostatic disturbances and microangiopathy. Linking the many direct and indirect effects on the vasculature to the reduction in key macrovascular outcomes reported with pioglitazone in patients with type 2 diabetes presents a considerable challenge. However, recent large-scale clinical cardiovascular imaging studies are beginning to provide some mechanistic insights, including a potentially important role for improvements in high-density lipoprotein cholesterol with pioglitazone. In addition to a role in prevention, animal studies also suggest that pioglitazone may minimize damage and improve recovery during and after ischaemic cardio- and cerebrovascular events. In this review, we consider potential cardiovascular protective mechanisms of pioglitazone by linking preclinical data and clinical cardiovascular outcomes guided by insights from recent imaging studies. Pioglitazone may influence CVD pathophysiology at multiple points in the disease process, including atherogenesis, plaque inflammation, plaque rupture and haemostatic disturbances (i.e. thrombus/embolism formation), as well as microangiopathy.

Metabolic syndrome as a prothrombogenic state

The prevalence of obesity has reached epidemic proportions nowadays. Abdominal obesity is the most unfavorable one, because of its association with the complex of markers and risk factors ofcardiovascular diseases and type 2 diabetes mellitus, which is called metabolic syndrome (MS). MS also increases risk of atherothrombosis because it is characterized by low fibrinolysis and prothrombogenic changes in coagulation and platelet hemostasis. The review highlights the mechanisms of hemostatic disturbances in MS, which eхends our scientific knowledge about pathogenesis of cardio vascular diseases

Haemostatic system, biochemical profiles, kynurenines and the prevalence of cardiovascular disease in peritoneally dialyzed patients

Introduction The haemostatic and biochemical abnormalities participate in the progression of cardiovascular disease (CVD) in peritoneally dialysed (PD) patients. Recently, the role of kynurenine (KYN) pathway of tryptophan (TRP) degradation in the development of CVD has been postulated. Materials and methods The present study was undertaken to investigate haemostatic parameters, biochemical profiles and kynurenines in PD patients both with and without CVD compared to age- and sex-matched healthy controls. Results The multiple biochemical abnormalities were present in PD patients, particularly in those with CVD. Tissue factor (TF), its inhibitor (TFPI), prothrombin fragment 1 + 2 (F 1 + 2 ) , urokinase-type plasminogen activator (uPA), its soluble receptor (suPAR), plasmin/antiplasmin (PAP) complexes, KYN, kynurenic (KYNA) and quinolinic (QA) acids levels were significantly higher, whereas TRP was significantly lower in the PD patients than in the controls. Tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) were higher in the patients with CVD than in the patients without CVD and controls. PD patients with CVD had higher F 1 + 2, and they had lower suPAR and KYNA levels compared with PD patients without CVD. KYNA was positively associated with TFPI, whereas its was inversely associated with F 1 + 2 both in the whole PD group and in CVD patients. Logistic regression analysis showed that low KYNA, high glucose, low HDL-cholesterol levels and the duration of dialysis treatment were independently associated with the presence of CVD in PD patients. Conclusions The present study suggests a relationship between kynurenine pathway of tryptophan degradation, haemostatic and biochemical disturbances and CVD prevalence in peritoneally dialyzed patients.

Experimental pathophysiology of systemic alterations induced by Bothrops asper snake venom

Moderate and severe envenomations by the snake Bothrops asper provoke systemic alterations, such as systemic bleeding, coagulopathy, hypovolemia, hemodynamic instability and shock, and acute renal failure. Systemic hemorrhage is a typical finding of these envenomations, and is primarily caused by the action of P-III snake venom metalloproteinases (SVMPs). This venom also contains a thrombin-like serine proteinase and a prothrombin-activating P-III SVMP, both of which cause defibrin(ogen)ation. Thrombocytopenia, predominantly induced by a C-type lectin-like protein, and platelet hypoaggregation, caused by the two defibrin(ogen)ating enzymes, also contribute to hemostatic disturbances, which potentiate the systemic bleeding induced by hemorrhagic SVMPs. Cardiovascular disturbances leading to shock are due to the combined effects of hemorrhagic toxins, other venom components that increase vascular permeability, the action of hypotensive agents in the venom and of endogenous mediators, and the potential cardiotoxic effect of some toxins. Renal alterations are likely to be caused by direct cytotoxicity of venom components in the kidney, and by renal ischemia resultant from hypovolemia and hypoperfusion. Lethality induced by B. asper venom is the consequence of several combined effects among which the action of P-III SVMPs is especially relevant.

O14 Haemostatic disturbances in women undergoing in vitro fertilization

O14 Haemostatic disturbances in women undergoing in vitro fertilization

EXPERIMENTAL ACUTE INFLAMMATORY REACTION AND HEMOSTATIC VARIABLES

Plasma fibrinogen levels and factor VIII:c activity were increased after intramuscular injections of turpentine in ten rabbits, which caused an acute inflammatory reaction, while plasma protein C activity (an anticoagulant mechanism) was slightly yet significantly decreased. The inflammatory reaction also caused an increase of plasma antithrombin III activity. These changes should be interpretated in the more complex context of hemostatic perturbations caused by the acute phase reaction and may be involved in the intravascular deposition of fibrin. Clinical and experimental studies have suggested that inflammation leads to complex hemostatic disturbances, consisting of the increase of procoagulant variables such as fibrinogen, clotting factor VIII, von Willebrand factor, but also of the stimulation of antithrombin III, an anticoagulant mechanism. On the other hand, plasma protein C, another potent anticoagulant mechanism decreases during the acute phase reaction.

Neutrophil elastase and syndecan shedding contribute to antithrombin depletion in murine anthrax

Bacillus anthracis infection is associated with severe hemostatic disturbances but their roles and contribution to fatality remain incompletely characterized. We undertook analyses of circulating antithrombin levels during the course of infection using a comparison of lethal and nonlethal murine anthrax models. Plasma samples were obtained from DBA/2 mice challenged intraperitoneally with the spores of either toxigenic B. anthracis Sterne strain or nontoxigenic, avirulent delta Sterne strain. We found that plasma antithrombin levels were rapidly depleted in Sterne spore-challenged mice, concomitant with elevation of neutrophil elastase (NE) and massive syndecan shedding from the liver into circulation. The shed syndecan bound with antithrombin accelerated NE-mediated antithrombin proteolysis. The liver response to infection demonstrated strain-specific compensatory increases of antithrombin and syndecan gene transcription. Both bacterial strains induced changes in blood coagulation parameters consistent with the onset of disseminated intravascular coagulation. We propose that antithrombin depletion proceeding through activation of neutrophils and massive shedding of heparin-like syndecan from the liver into circulation contribute to anthrax coagulopathy.

Clinical Utility of the PFA-100

The PFA-100 (platelet function analyzer) is a relatively new tool for the investigation of primary hemostasis. This article reviews the history of the PFA-100 and details its clinical utility in several settings. The PFA-100 was first introduced to us in 1995 in an issue of Seminars in Thrombosis And Hemostasis, which included data from a field trial headed by Dr. Eberhard Mammen. Since that time, the PFA-100 has featured in nearly 500 publications and some 35 reviews. The PFA-100 has potential utility in monitoring antiplatelet therapy (including aspirin) and as a screening tool for investigating possible von Willebrand disease (VWD) and various platelet disorders. The PFA-100 also has potential value for monitoring DDAVP (desmopressin) therapy in both VWD and functional platelet disorders. Most recent attention has focused on sensitivity to antiplatelet medication, where a new language has also emerged, with researchers talking about "aspirin resistance," "aspirin responsiveness," and "aspirin nonresponsiveness." Ultimately, the greatest strengths of the PFA-100 are its simplicity in use and excellent sensitivity to various hemostatic disturbances. However, because it is a "global" test system for primary hemostasis, this also creates a significant limitation because the PFA-100 is not specific for, nor predictive of, any particular disorder. However, used appropriately, the PFA-100 can be considered a worthwhile addition to hemostasis laboratories involved in the identification or therapeutic monitoring of primary hemostatic disorders. The potential future applications for this simple instrument are also briefly assessed.

Activated protein C levels in obesity and weight loss influence

Obesity is associated with a high risk of cardiovascular events. Several haemostatic disturbances which could contribute to this increased risk have been described in obesity; nevertheless, the state of coagulation inhibitors has been scarcely studied in these patients. The aim of the present study was to compare activated protein C levels in obese patients and in a control group, and to evaluate the effect of weight loss. In 67 severe or morbid obese patients, an evaluation was performed at baseline and 3 months after diet. The same determinations were performed in 67 healthy volunteers with normal body weight. We also quantified the levels of protein C and prothrombin fragment 1 + 2. Obese patients showed significantly higher levels of activated protein C, protein C and fragment 1 + 2. No correlation was found between activated protein C and fragment 1 + 2 levels in obese patients. After three months of diet, a significant decrease in activated protein C and fragment 1 + 2 was observed. In conclusion, activated protein C levels are increased in obese patients, but only a minor fraction of this increase may be explained by the higher thrombin generation and C protein levels. Activated protein C levels decrease with weight loss, due in part to a thrombin generation reduction.

Development of Spontaneous Subdural Hematoma and Bone Marrow Depression after Hydroxyethyl Starch Administration

Although hydroxyethyl starch (HES) solutions are known to interfere with hemostasis, the various available HES preparations are frequently used in clinical practice for volume therapy and to improve blood rheology. 1 Kozek-Langenecker S.A. Effects of hydroxyethyl starch solutions on hemostasis. Anesthesiology. 2005; 103: 654-660 Crossref PubMed Scopus (228) Google Scholar We report a serious hemostatic disturbance in a 17-month-old toddler after the infusion of 6% HES 450/0.72 over 10 days, resulting in cutaneous bleeding and subdural hematoma necessitating surgical intervention. In addition, severe pruritis occurred, and histiocytes with hydroxyethyl starch–associated vacuoles were found in aspirated bone marrow, combined with severe hyporegenerative anemia and thrombopenia.

Relationship between maternal and cord blood hemostatic disturbances in preeclamptic pregnancies

Endothelial cell activation or damage is believed to play a key role in preeclampsia (PE) and may underlie the hemostatic changes observed in this syndrome. The aim of this study was to evaluate a relationship between maternal and cord blood hemostatic disturbances in preeclamptic pregnancies. We measured the plasma levels of tissue plasminogen activator (tPA) antigen and of plasminogen activator inhibitor type 1 (PAI-1) antigen, both markers of hemostatic and endothelial function, and fibrin fragment D-dimer. Maternal blood from uncomplicated ( n = 42) and PEc pregnancies ( n = 44) were collected before delivery, and umbilical cord blood (UCB) immediately after delivery. In preeclamptic cases, UCB presented significantly higher tPA values and significantly lower PAI-1/tPA ratio. Preeclamptic women also presented significantly higher tPA, as well as PAI-1 values, when compared with normal pregnant women; no significant difference was found for D-dimer. In preeclamptic women, proteinuria (a marker of PE severity) correlated positively and significantly with tPA and PAI-1 antigen levels. An inverse relationship between maternal tPA antigen levels and fetal birth weigh in PE was also observed. Our data show that the hemostatic maternal disturbances observed in preeclamptic women have similarities with the UCB circulation, and that endothelial dysfunction is the most plausible underlying cause. Moreover, maternal hemostatic disturbances seem to be associated with the severity of PE. Further studies are needed to strength the values of tPA and PAI-1 as markers of severity in PE.

Correction of the Fibrinolytic Type of the Disseminated Intravascular Coagulation Syndrome in the Early Postoperative Period

Objective: to comparatively evaluate the efficiency and safety of trasylol and aprotex used in the treatment of the fibrinolytic type of disseminated intravascular coagulation (DIC) syndrome after long abdominal operations. Materials and methods. The authors examined patients undergone long abdominal operations (pancreatoduodenal resection, hemihepatectomy, hemicolectomy, reconstructive operations on the bile duct) and those with a pyoseptic process (peritonitis, pancreatonecrosis) who had on admission to the intensive care unit the signs of fibrinolytic DIC syndrome: elevated levels of fibrin/fibrinogen degradation products > 10 ^g/ml, shorter euglobulin lysis < 180 min, and increased fibrinolytic potential (> 1.1 conventional unit) in the presence of a porous clot, as evidenced by an electrocoagulogram. Results. The use of protease inhibitors in the fibrinolytic type of the DIC syndrome in the early postoperative period could reduce needs for blood transfusion by 47—67%, fresh frozen plasma transfusion by 47-68%, and drainage losses by 57—73%. As compared with the baseline values, there was no significant difference with the use of small-dose trasylol. Conclusion. In the fibrinolytic type of DIC syndrome, aprotinin should be an integral part of intensive care. Comparison of the efficacy of trasylol and aprotex suggest the equivalence of both aprotinin drugs used in equivalent doses. It is unacceptable to use of small-dose aprotinin in surgery as this makes it impossible to rapidly correct hemostatic disturbances and thus to reduce blood loss.

Risk of excessive bleeding associated with marginally low von Willebrand factor and mild platelet dysfunction.

Bleeding symptoms are so commonly reported that it is not known whether they associate causally or coincidentally with mild but measurable primary hemostatic defects. OBJECTIVES/PATIENTS/METHODS: In order to evaluate if the mild primary hemostatic defects are truly causative of increased bleeding symptoms, we surveyed a population of healthy teenagers for bleeding symptoms. Using a case-control approach, we then estimated the risk of excessive bleeding associated with low von Willebrand factor (defined as VWF below the 5th percentile of a normal reference population), and with mild platelet dysfunction [PD, defined as concurrent reduced platelet aggregation responses to two agonists (adenosine diphosphate and epinephrine)]. Excessive bleeding was present in 63 out of 809 teenagers (7.8%). Among the 49 cases who were tested for VWF, low values by three measures were more commonly present than in 166 controls, specifically, ristocetin cofactor (RCo) activity [20.4% vs. 5.4%, odds ratio (OR) 4.5], collagen binding (14.3% vs. 4.2%, OR 3.8), and antigen level (20.4% vs. 6.0%, OR 4.0). The low RCo values ranged from 35 to 45 U dL(-1) except for a single case with 26 U dL(-1). Of the 47 teenagers with excessive bleeding who underwent platelet aggregation studies, reduced responses were more common than in controls (12.8% vs. 4.4%, OR 3.2). Twenty-nine per cent of cases with excessive bleeding had either low RCo or PD. Almost one in three teenagers who report excessive bleeding is likely to have a measurable hemostatic disturbance manifested either by marginally low VWF (by three measures) or by mild PD.

Suramin counteracts the haemostatic disturbances produced by Bothrops jararaca snake venom

Snakebite accidents produced by Bothrops jararaca typically results in haemostatic changes including pro- and anticoagulant disturbs as well as interference with platelets. Suramin is a hexasulfonated naphthylurea derivative that was recently characterized as a thrombin inhibitor (Monteiro et al., 2004. Suramin interaction with human alpha-thrombin: inhibitory effects and binding studies. Int. J. Biochem. Cell Biol. 36(10), 2077–2085). Here, we evaluated the ability of suramin to counteract some of the haemostatic disturbs produced by B. jararaca venom. In vitro assays showed that suramin inhibited venom-induced hydrolysis of a number of synthetic substrates: S-2238, S-2266, S-2302 and S-2288, being this ability more prominent towards the thrombin substrate S-2238 (IC 50=4.3 μM). It was also observed that suramin impaired the fibrinogen clotting induced by B. jararaca venom (IC 50=124 μM). Accordingly, increasing concentrations of suramin progressively delayed venom-induced plasma clotting, with complete inhibition attained at concentrations above 1.0 mM. In addition, the platelet-aggregating properties of B. jararaca venom were inhibited by suramin in a dose-dependent fashion (IC 50=127 μM). Suramin showed no effect in the in vivo hemorrhagic effect of venom in mouse skin. The in vivo effect of suramin was further tested using a previously established venous thrombosis model in rats induced by intravenous administration of B. jararaca venom combined with stasis. Venom doses of 100 μg/kg produced 100% of thrombus incidence (10.6±1.7 mg). On the other hand, previous administration of suramin partially inhibited thrombus formation. Thus, 12.5 or 25 mg/kg of suramin decreased thrombus weight by 24% and 40%, respectively. Remarkably, co-administration of 3 μL/kg of antibothropic serum (which has no effect on thrombus formation) and 12.5 mg/kg of suramin decreased thrombus weight by 75%, suggesting a synergic effect. Altogether, we demonstrate here that suramin inhibits in vitro and in vivo haemostatic changes caused by B. jararaca venom. At this point, this drug could be of potential interest for association with conventional antiserum therapy.

Hypertonic-Hyperoncotic Solutions Improve Cardiac Function in Children After Open-Heart Surgery

Hypertonic-Hyperoncotic Solutions Improve Cardiac Function in Children After Open-Heart Surgery

Role of interleukin-6 in fibrinolytic changes induced by lipopolysaccharide in mice

We have recently demonstrated that interleukin (IL)-6 is protective against coagulatory and hemostatic disturbance and subsequent pulmonary hemorrhage induced by bacterial endotoxin, at least partly, via the inhibition of proinflammatory cytokines and chemokines using IL-6-null [IL-6(-/-)] mice and corresponding wild-type mice. Its role in fibrinolytic systems remains undefined, however. The present study elucidated the role of IL-6 in the activity of alpha(2)-plasmin inhibitor, an inhibitor of fibrinolysis, during inflammation induced by intraperitoneal administration of lipopolysaccharide in IL-6(-/-) and wild-type mice. Both IL-6(-/-) and wild-type mice were injected with vehicle or lipopolysaccharide (1 mg/kg). Seventy-two hours later, blood samples were collected and alpha(2)-plasmin inhibitor activity was examined. Lipopolysaccharide challenge induced significant enhancement of alpha(2)-plasmin inhibitor activity as compared with vehicle challenge in wild-type mice, but not in IL-6(-/-) mice. In the presence of lipopolysaccharide, the activity was significantly lower in IL-6(-/-) mice than that in wild-type mice. These results indicate that IL-6 can, at least partly, inhibit the lipopolysaccharide-enhanced fibrinolysis via the enhanced alpha2-plasmin inhibitor activity.

Platelet Dysfunction in Asphyxiated Newborn Piglets Resuscitated with 21% and 100% Oxygen

Hemostatic disturbances are common in asphyxiated newborns after resuscitation. We compared platelet function in hypoxic newborn piglets reoxygenated with 21% or 100% oxygen. Piglets (1-3 d, 1.5-2.1 kg) were anesthetized and acutely instrumented for hemodynamic monitoring. After stabilization, normocapnic hypoxia was induced with an inspired oxygen concentration of 10-15% for 2 h. Piglets were then resuscitated for 1 h with 21% or 100% oxygen, followed by 3 h with 21% oxygen. Platelet counts and collagen (2, 5, and 10 microg/mL)-stimulated whole blood aggregation were studied before hypoxia and at 4 h of post-hypoxia/reoxygenation. Platelet function was studied using transmission electron microscopy and by measuring plasma thromboxane B2 (TxB2) and matrix metalloproteinase (MMP)-2 and -9 levels. Control piglets were sham-operated without hypoxia/reoxygenation. The hypoxemic (PaO2 33 mm Hg) piglets developed hypotension with metabolic acidosis (pH 7.02-7.05). Upon reoxygenation, piglets recovered and blood gases gradually normalized. At 4 h reoxygenation, platelet aggregation ex vivo was impaired as evidenced by a rightward-downward shifting of the concentration-response curves. Electron microscopy showed features of platelet activation. Plasma MMP-9 but not MMP-2 activity significantly increased. Resuscitation with 100% but not 21% oxygen increased plasma TxB2 levels. Platelet counts decreased after hypoxia/reoxygenation but were not different between groups during the experiment. Resuscitation of hypoxic newborn piglets caused platelet activation with significant deterioration of platelet aggregation ex vivo and increased plasma MMP-9 levels. High oxygen concentrations may aggravate the activation of prostaglandin-thromboxane mechanistic pathway.