Natural anticoagulant inhibitors: activated Protein C

Congenital Portosystemic Shunts in Dogs and Cats: Classification, Pathophysiology, Clinical Presentation and Diagnosis

Congenital portosystemic shunts (CPSS) are abnormal vascular communications between the portal and the systemic circulation, bypassing the hepatic parenchyma and resulting in liver hypoplasia and hepatic insufficiency. Such connections develop in utero and persist postnatally. CPSS are among the two most common congenital vascular anomalies of the liver in small animals, along with primary hypoplasia of the portal vein without portal hypertension (PHPV without PH). CPSS can be extrahepatic (ECPSS), most commonly diagnosed in small and toy breed dogs and cats, or intrahepatic (ICPSS), most commonly seen in large breed dogs. Single ECPSS is the most common type encountered in both dogs and cats. Clinical signs of CPSS are non-specific and may wax and wane, while laboratory findings can raise clinical suspicion for CPSS, but they are also not specific. Definitive diagnosis will be established by evaluation of liver function tests, such as determination of fasting plasma ammonia (FA) levels, and pre- and postprandial serum bile acids concentrations, and diagnostic imaging. The purpose of this article is to review the definition, classification, pathogenesis, clinical presentation, and diagnosis of CPSS in dogs and cats, highlighted by the authors' clinical experience.

Purpura Fulminans: a Rare but Fierce Presentation of Pneumococcal Sepsis

Infectious purpura fulminans (PF) is a rare presentation of disseminated intravascular coagulopathy (DIC) due to diffuse intravascular thrombosis and haemorrhagic infarction of the skin. PF can present in infancy/childhood or adulthood and usually presents as ecchymotic skin lesions, fever and hypotension. It is most commonly a consequence of sepsis related to Neisseria meningitidis, Streptococcus pneumoniae or Haemophilus influenzae. Despite aggressive management of sepsis with intravenous fluids, antibiotics, and conventional and nonconventional therapies, the condition still carries a mortality rate of 43%^[1]. Streptococcus pneumoniae mostly presents with community-acquired pneumonia. We present a case of PF secondary to DIC related to Pneumococcal sepsis in an otherwise healthy and immunocompetent patient.

Multispecies Probiotic Supplementation Favorably Affects Vascular Function and Reduces Arterial Stiffness in Obese Postmenopausal Women-A 12-Week Placebo-Controlled and Randomized Clinical Study

Obesity in the postmenopausal period is associated with an increased risk of cardiovascular diseases in women. One of the key drivers of cardiovascular risk is endothelial dysfunction; thus, this is also a crucial point for studies on new therapeutic methods of cardioprotective properties. The aim of the current study was to evaluate the effect of two doses of multispecies probiotic Ecologic® Barrier supplement on functional (primary endpoint) and biochemical parameters (secondary endpoint) of endothelial dysfunction in obese postmenopausal women in a 12-week randomized, placebo-controlled clinical trial. A total of 81 obese Caucasian women participated in the trial. The subjects were randomly assigned to three groups that received a placebo, a low dose (LD) (2.5 × 10⁸ colony forming units (CFU) per day), or a high dose (HD) (1 × 1010 CFU per day) of lyophilisate powder containing live multispecies probiotic bacteria. The probiotic supplement was administered each day for 12 weeks in two equal portions. A high dose probiotic supplementation for 12 weeks decreased systolic blood pressure, vascular endothelial growth factor, pulse wave analysis systolic pressure, pulse wave analysis pulse pressure, pulse wave analysis augmentation index, pulse wave velocity, interleukin-6, tumor necrosis factor alpha, and thrombomodulin. Low doses of probiotic supplementation decreased the systolic blood pressure and interleukin-6 levels. The mean changes in the estimated parameters, compared among the three groups, revealed significant differences in the vascular endothelial growth factor, the pulse wave analysis systolic pressure, the pulse wave analysis augmentation index, the pulse wave velocity, the tumor necrosis factor alpha, and thrombomodulin. The post hoc tests showed significant differences for all parameters between HD and the placebo group, and HD and LD (besides pulse wave analysis augmentation index). We show for the first time that supplementation with multispecies probiotic Ecologic® Barrier favorably modifies both functional and biochemical markers of vascular dysfunction in obese postmenopausal women.

Recombinant human activated protein C for severe sepsis in neonates

BACKGROUND

Sepsis is a common problem in preterm and term infants. The incidence of neonatal sepsis has declined, but mortality remains high. Recombinant human activated protein C (rhAPC) possess a broad spectrum of activity modulating coagulation and inflammation. In septic adults it may reduce mortality, but no significant benefit has been reported in children with severe sepsis.

OBJECTIVES

To determine whether treatment with rhAPC reduces mortality and/or morbidity in neonatal sepsis.

SEARCH METHODS

For this update searches were carried out in May 2011 of the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and abstracts of annual meetings of the Pediatric Academic Societies. Doctoral dissertations, theses and the Science Citation Index for articles on activated protein C were searched. No language restriction was applied.

SELECTION CRITERIA

Randomized or quasi-randomized trials, assessing the efficacy of rhAPC compared to placebo or no intervention as an adjunct to antibiotic therapy of suspected or confirmed severe sepsis in term and preterm infants less than 28 days old. Eligible trials should report at least one of the following outcomes: mortality during initial hospital stay, neurodevelopmental assessment at two years of age or later, length of hospital stay, duration of ventilation, chronic lung disease, periventricular leukomalacia, intraventricular haemorrhage, necrotizing enterocolitis, bleeding, and any other adverse events.

DATA COLLECTION AND ANALYSIS

Review authors were to independently evaluate the articles for inclusion criteria and quality, and abstract information for the outcomes of interest. Differences were to be resolved by consensus. The statistical methods were to include relative risk, risk difference, number needed to treat to benefit or number needed to treat to harm for dichotomous and weighed mean difference for continuous outcomes reported with 95% confidence intervals. A fixed effect model was to be used for meta-analysis. Heterogeneity tests, including the I(2) statistic, were to be performed to assess the appropriateness of pooling the data.

MAIN RESULTS

No eligible trials were identified. In October 2011 rhAPC (Xigris®) was withdrawn from the market by Eli Lilly due to a higher mortality in a trial among adults. Xigris® (DrotAA)( rhAPC) should no longer be used in any age category and the product should be returned to the distributor.

AUTHORS' CONCLUSIONS

Despite the scientific rationale for its use, there is insufficient data to use rhAPC for the management of severe sepsis in newborn infants. Due to the results among adults with lack of efficacy, an increase in bleeding and resulting withdrawal of rhAPC from the market, neonates should not be treated with rhAPC and further trials should not be conducted.

Protein C activity in dogs: adaptation of a commercial human colorimetric assay and evaluation of effects of storage time and temperature

Objectives of this study were to adapt a commercial human protein C (PC) colorimetric assay for use in dogs and to investigate effects of various storage conditions. The human assay was modified by using pooled canine plasma for calibration and by increasing the activation time. PC activity was measured in fresh canine plasma and in plasma stored under various conditions. PC activity of some stored samples was significantly different from that of fresh plasma; however, differences were small. No difference was detected in samples stored under similar conditions but analyzed in different laboratories using similar methodology. Results of this study indicate that the human colorimetric assay is suitable for canine samples if pooled canine plasma is used for calibration, that Clinical and Laboratory Standards Institute sample storage guidelines developed for testing in humans are appropriate for dogs, and that comparisons of results from laboratories using similar methodology are legitimate.

Inflammation and the mucosal microcirculation in inflammatory bowel disease: the ebb and flow

PURPOSE OF REVIEW

Inflammatory bowel disease pathogenesis involves the interplay of multiple biological factors, among which nonimmune cells, including the endothelium, represent a crucial component of disease pathogenesis.

RECENT FINDINGS

Endothelial cells play a key role in chronic inflammation through multiple and disparate activities. The mucosal microvasculature in inflammatory bowel disease is dysfunctional, overexpresses inflammatory molecules and undergoes intense angiogenesis, failing to exert its physiological antiinflammatory and anticoagulant activities.

SUMMARY

The mucosal microcirculation is abnormal in inflammatory bowel disease and represents a novel component of disease pathogenesis; targeting the various abnormalities of the inflammatory bowel disease microcirculation may lead to new forms of therapeutic intervention.

Purpura Fulminans in Sepsis

Sepsis-induced purpura fulminans is a rare but life-threatening disorder, characterized by hemorrhagic infarction of the skin caused by disseminated intravascular coagulation and dermal vascular thrombosis. The pathogenesis is linked to enhanced expression of the natural procoagulants and depletion of the natural anticoagulant proteins particularly protein C. Meningococcal sepsis is the most common cause, followed by pneumococcal sepsis in adults. The syndrome is associated with more than 50% mortality secondary to multiple organ dysfunction syndrome and is accompanied by long-term morbidity. Necrotic lesions usually progress to distal ischemia, and skin grafting and extremities or limb amputation are often required. Early antibiotic administration and intensive care management according to the recommendations of severe sepsis and shock is crucial for patients' survival. Adjuvant therapies against inflammatory and coagulation cascades and augmenting fibrinolysis are still controversial and need further assessment. Among them activated protein C and supplementation therapy have given promising results.

The interaction between pathogens and the host coagulation system

There is mounting evidence that the hemostatic system is critical in host responses to bacterial infection. Invasive bacteria have evolved virulence strategies to interact with host hemostatic factors such as plasminogen and fibrinogen for infection. Furthermore, genetic variations in host hemostatic factors also influence host response to bacterial infection.

Recombinant human activated protein C for severe sepsis in neonates

BACKGROUND

Sepsis is a common problem in both preterm and term infants. Although the overall incidence of neonatal sepsis has declined over the past decade, mortality remains high. Recombinant human activated protein C (rhAPC) has been shown to possess a broad spectrum of activity modulating coagulation and has been shown in septic adults to reduce mortality. In septic children, an open label study has shown similar pharmacokinetics, adverse reaction profile and frequency as in adults with severe sepsis.

OBJECTIVES

To determine whether treatment with rhAPC will reduce mortality and/or morbidity in neonates with severe sepsis.

SEARCH STRATEGY

Searches were carried out in July 2005 by the review authors independently of MEDLINE (1966 to July 2005), EMBASE (1980 to July 2005), CINAHL (1982 to July 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2005), abstracts of annual meetings of the Pediatric Academic Societies and Society for Pediatric Research which were published in Pediatric Research from 1980, and contacts were made with subject experts. Doctoral dissertations, theses and the Science Citation Index for articles on activated protein C were searched from 1980. No language restriction was applied.

SELECTION CRITERIA

Studies were included if they were randomized or quasi-randomized trials, assessing the efficacy of rhAPC compared to placebo or no intervention as an adjunct to antibiotic therapy of suspected or confirmed severe sepsis in term and preterm infants less than 28 days old. Eligible trials were required to report treatment effects on at least one of the following outcomes: all cause mortality during initial hospital stay, neurological development and neurodevelopmental assessment at two years of age or later, length of hospital stay, duration of ventilation, chronic lung disease in survivors, periventricular leukomalacia, intraventricular hemorrhage, necrotizing enterocolitis, bleeding, and any other adverse events.

DATA COLLECTION AND ANALYSIS

Both review authors independently evaluated the papers for inclusion criteria and quality, and abstracted information for the outcomes of interest. Differences were resolved by mutual discussion. The statistical methods were to include relative risk, risk difference, number needed to treat to benefit or number needed to treat to harm for dichotomous and weighed mean difference for continuous outcomes reported with 95% confidence intervals. A fixed effects model was to be used for meta-analysis. Heterogeneity tests, including the I(2) statistic, were to be performed to assess the appropriateness of pooling the data.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

Despite the scientific rationale for its use, there are insufficient data to support the use of rhAPC for the management of severe sepsis in newborn infants. There is a need for large well-designed trials to elucidate the effectiveness of rhAPC to reduce mortality and adverse outcomes in neonates with severe sepsis. The results of such trials would guide clinical practice. Currently, a cautious approach to the use of rhAPC is warranted due to the high incidence of bleeding with its use; especially as severe sepsis in preterm infants is commonly associated with bleeding problems and intraventricular hemorrhage. Its use is not recommended outside of randomized controlled trials.

Preconditioning of primary human endothelial cells with inflammatory mediators alters the "set point" of the cell

Endothelial cells are highly sensitive to changes in the extracellular milieu. Sepsis results in activation of inflammatory and coagulation pathways. We hypothesized that sepsis-associated mediators may alter the response capacity (so-called "set point") of endothelial cells. Human umbilical vein endothelial cells (HUVEC) were preincubated in the presence or absence of tumor necrosis factor (TNF)-alpha, lipopolysaccharide (LPS), hypoxia, hyperthermia, and/or high glucose; treated with or without thrombin for 4 h; and then processed for RNase protection assays of selected activation markers. Priming with TNF-alpha and LPS significantly inhibited thrombin-mediated induction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, tissue factor, and E-selectin, but not platelet-derived growth factor-A or CD44. In electrophoretic mobility shift assays, thrombin-treated HUVEC demonstrated inducible binding of p65 NF-kappaB, an effect that was significantly blunted by pretreatment of cells with TNF-alpha and LPS. Consistent with these results, TNF-alpha and LPS attenuated the effect of thrombin on IkappaB phosphorylation, total cytoplasmic IkappaB, and nuclear translocation of p65 NF-kappaB. The inhibitory effect of TNF-alpha on thrombin signaling persisted for up to 24 h following removal of the cytokine. Taken together, these data suggest that inflammatory mediators prime endothelial cells to modulate subsequent thrombin response.

Sepsis and coagulation

The host response to infection is a highly complex yet well-orchestrated process that involves an elaborate array of soluble mediators and cells. Normally, the host response prevails in containing and eliminating the pathogenic threat. When excessive or sustained, however, the host response may "turn on its bearer" and lead to organ dysfunction. Severe sepsis is invariably associated with activation of primary and secondary hemostasis. This article describes sepsis-associated changes in coagulation, discusses the putative role for these changes in pathogenesis of the sepsis syndrome, and outlines current diagnostic and therapeutic strategies.

The anticoagulant protein C pathway

The anticoagulant protein C system regulates the activity of coagulation factors VIIIa and Va, cofactors in the activation of factor X and prothrombin, respectively. Protein C is activated on endothelium by the thrombin-thrombomodulin-EPCR (endothelial protein C receptor) complex. Activated protein C (APC)-mediated cleavages of factors VIIIa and Va occur on negatively charged phospholipid membranes and involve protein cofactors, protein S and factor V. APC also has anti-inflammatory and anti-apoptotic activities that involve binding of APC to EPCR and cleavage of PAR-1 (protease-activated receptor-1). Genetic defects affecting the protein C system are the most common risk factors of venous thrombosis. The protein C system contains multi-domain proteins, the molecular recognition of which will be reviewed.