Plasma endothelin-1 and clinical manifestations of neonatal sepsis

Hemodynamic dysfunction in neonatal sepsis

Cardiovascular disturbances are a frequent occurrence in neonatal sepsis. Preterm and term infants are particularly vulnerable due to the unique features of their cardiovascular function and reserve, compared to older children and adults. The clinical manifestations of neonatal sepsis are a product of the variable inflammatory pathways involved (warm vs. cold shock physiology), developmental state of the cardiovascular system, and hormonal responses. Targeted neonatal echocardiography has played an important role in advancing our knowledge, may help delineate specific hemodynamic phenotypes in real-time, and supports an individualized physiology-based management of sepsis-associated cardiovascular dysfunction. IMPACT: Cardiovascular dysfunction is a common sequela of sepsis. This review aims to highlight the pathophysiological mechanisms involved in hemodynamic disturbance in neonatal sepsis, provide insights from targeted neonatal echocardiography-based clinical studies, and suggest its potential incorporation in day-to-day management.

Endothelins in inflammatory neurological diseases

Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.

Sepsis and Oxidative Stress in the Newborn: From Pathogenesis to Novel Therapeutic Targets

Sepsis is at present one of the leading causes of morbidity and mortality in the neonatal population. Together with inflammation, oxidative stress is involved in detrimental pathways activated during neonatal sepsis, eventually leading to organ dysfunction and death. The redox cascade during sepsis is mainly initiated by IL-6 and IL-8 stimulation in newborns and includes multiple noxious processes, as direct cell damage induced by reactive oxygen species, activation of gene expression leading to amplification of inflammation and oxidative stress, and impairment of mitochondrial function. Once proinflammatory and prooxidant pathways are established as stimulated by causing pathogens, self-maintaining unfavorable redox cycles ensue, leading to oxidative stress-related cellular damage, independently from the activating pathogens themselves. Despite antioxidant systems are induced during neonatal sepsis, as an adaptive response to an increased oxidative burden, a condition of redox imbalance favoring oxidative pathways occurs, resulting in increased markers of oxidative stress damage. Therefore, antioxidant treatment would exert beneficial effects during neonatal sepsis, potentially interrupting prooxidant pathways and preventing the maintenance of detrimental redox cycles that cannot be directly affected by antibiotic treatment. Among others, antioxidant agents investigated in clinical settings as adjunct treatment for neonatal sepsis include melatonin and pentoxifylline, both showing promising results, while novel antioxidant molecules, as edaravone and endothelin receptor antagonists, are at present under investigation in animal models. Finally, mitochondria-targeted antioxidant treatments could represent an interesting line of research in the treatment of neonatal sepsis.

Effects of Erdosteine in Experimental Sepsis Model in Rats

Objective

Erdosteine is a mucolytic agent that is known to possess antioxidant effects. This study investigated the effects of erdosteine on endothelin-1 (ET-1) levels and oxidative stress parameters superoxide dismutase (SOD) and malondialdehyde (MDA) in a rat sepsis model.

Methods

Four groups of Wistar albino rats (n=8 per group) were randomly allocated to the following groups: sham (group 1), sepsis (group 2), erdosteine control (group 3) and a sepsis group pretreated with erdosteine (group 4). Sepsis was induced using E. Coli ATCC 25922 inoculation. Serum ET-1, liver tissue SOD and MDA levels were determined in all groups.

Results

ET-1 levels were significantly higher in group 2 compared to groups 1, 3 and 4 (p<0.001, p=0.002 and p<0.001, respectively). Similarly, MDA levels in groups 1, 3 and 4 were significantly lower relative to group 2 (p<0.001, p=0.022 and p=0.010, respectively). Additionally, SOD activities in these same three groups were found to be significantly higher than those in group 2 (p<0.001, p=0.004 and p=0.028, respectively).

Conclusion

In conclusion, erdosteine decreases ET-1 levels and ameliorates oxidative stress parameters induced by sepsis in an experimental rat model of sepsis.

Role of endothelial nitric oxide synthase and endothelin-1 polymorphism genes with the pathogenesis of intraventricular hemorrhage in preterm infants

In the pathogenesis of neonatal intraventricular hemorrhage (IVH) in preterm infants, an important role is played by changes in venous and arterial cerebral flows. It has been shown that the ability of autoregulation of cerebral flows in response to variations in arterial blood pressure in preterm infants is impaired. This impaired autoregulation causes an increased risk of germinal matrix rupture and IVH occurrence. We examined three polymorphisms of genes, related to regulation of blood flow, for an association with IVH in 100 preterm infants born from singleton pregnancy, before 32 + 0 weeks of gestation, exposed to antenatal steroids therapy, and without congenital abnormalities. These polymorphisms include: eNOS (894G > T and -786T > C) and EDN1 (5665G > T ) gene. We found that infants with genotype GT eNOS 894G > T have 3.4-fold higher risk developing of IVH born before 28 + 6 weeks of gestation. Our investigation did not confirm any significant prevalence for IVH development according to eNOS -786T > C genes polymorphism. Our novel investigations in EDN1 5665G > T polymorphism did not show any link between alleles or genotypes and IVH. Future investigations of polymorphisms in blood-flow associated genes may provide valuable insight into the pathogenetic mechanisms underlying the development of IVH.

Endothelin-1-Rho kinase interactions impair lung structure and cause pulmonary hypertension after bleomycin exposure in neonatal rat pups

Bronchopulmonary dysplasia (BPD) is the chronic lung disease associated with premature birth, characterized by impaired vascular and alveolar growth. In neonatal rats bleomycin decreases lung growth and causes pulmonary hypertension (PH), which is poorly responsive to nitric oxide. In the developing lung, through Rho kinase (ROCK) activation, ET-1 impairs endothelial cell function; however, whether ET-1-ROCK interactions contribute to impaired vascular and alveolar growth in experimental BPD is unknown. Neonatal rats were treated daily with intraperitoneal bleomycin with and without selective ETA (BQ123/BQ610) and ETB (BQ788) receptor blockers, nonselective ET receptor blocker (ETRB) (bosentan), or fasudil (ROCK inhibitor). At day 14, lungs were harvested for morphometrics, and measurements of Fulton's index (RV/LV+S), medial wall thickness (MWT), and vessel density. Lung ET-1 protein and ROCK activity (phospho-MYPT-1:total MYPT-1 ratio) were also measured by Western blot analysis. Bleomycin increased lung ET-1 protein expression by 65%, RV/LV+S by 60%, mean linear intercept (MLI) by 212%, and MWT by 140% and decreased radial alveolar count (RAC) and vessel density by 40 and 44%, respectively (P < 0.01 for each comparison). After bleomycin treatment, fasudil and bosentan partially restored RAC and vessel density and decreased MLI, RV/LV+S, and MWT to normal values. Bleomycin increased ROCK activity by 120%, which was restored to normal values by bosentan but not selective ETRB. We conclude that ET-1-ROCK interactions contribute to decreased alveolar and vascular growth and PH in experimental BPD. We speculate that nonselective ETRB and ROCK inhibitors may be effective in the treatment of infants with BPD and PH.

A Systematic Review: The Utility of the Revised Version of the Score for Neonatal Acute Physiology Among Critically Ill Neonates

The revised version of the Score for Neonatal Acute Physiology (SNAP-II) has been used across all birth weights and gestational ages to measure the concept of severity of illness in critically ill neonates. The SNAP-II has been operationalized in various ways across research studies. This systematic review seeks to synthesize the available research regarding the utility of this instrument, specifically on the utility of measuring severity of illness sequentially and at later time points. A systematic review was performed and identified 35 research articles that met inclusion and exclusion criteria. The majority of the studies used the SNAP-II instrument as a measure of initial severity of illness on the first day of life. Six studies utilized the SNAP-II instrument to measure severity of illness at later time points and only 2 studies utilized the instrument to prospectively measure severity of illness. Evidence to support the use of the SNAP-II at later time points and prospectively is lacking and more evidence is needed.

Endothelin 1 in healthy foals and in foals affected by neonatal diseases

In newborn babies, endothelin 1 (ET-1), a potent vasoconstrictor, increases during septicemia and severe respiratory syndromes. Because equine neonatal sepsis (ENS) and perinatal asphyxia syndrome (PAS) are major causes of morbidity and mortality in newborn foals and because no information on the concentration of ET-1 in healthy and sick foals has been reported yet, the aims of this study were (1) to define the serum concentration of Big ET-1 in healthy neonatal foals during the first week of age; (2) to preliminarily explore the diagnostic and prognostic role of Big ET-1 during ENS and PAS. Six healthy and 23 sick foals affected by ENS and/or PAS were enrolled in the study. In healthy foals, Big ET-1 concentration increased in the first hours of life until 24 hours after birth, and it remained constant during the first 3 days, then gradually decreased becoming significantly lower from Day 4 onward (P < 0.05). In sick foals, only 26.1% of animals showed higher values of Big ET-1 than controls at admission, and no difference between surviving and nonsurviving foals was found. Because in nonsurviving foals, Big ET-1 remained over the maximum value recorded in clinically healthy horses or, when normal at admission, increased over time; this study suggested that repeated measurement of Big ET-1 during hospitalization may be helpful in monitoring the course of the disease. In conclusion, possible prognostic information may be obtained by repeated analysis of Big ET-1 during hospitalization, but further studies are needed.

Value of caffeic acid phenethyl ester pretreatment in experimental sepsis model in rats

Background and Aim. The aim of this study was to determine the actions of caffeic acid phenethyl ester (CAPE) on the changes of endothelin-1 (ET-1) level, tumor necrosis factor- (TNF-) alpha, and oxidative stress parameters such as superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in experimental sepsis model in rats. Materials and Methods. Twenty-four rats were randomly divided into three experimental groups: sham (group 1), sepsis (group 2), and sepsis + CAPE (group 3), n = 8 each. CAPE was administered (10 µmol/kg) intraperitoneally to group 3 before sepsis induction. Serum ET-1, serum TNF-alpha, tissue SOD activity, and tissue MDA levels were measured in all groups. Results. Pretreatment with CAPE decreased ET-1, TNF-alpha, and MDA levels in sepsis induced rats. Additionally SOD activities were higher in rats pretreated with CAPE after sepsis induction. Conclusion. Our results demonstrate that CAPE may have a beneficial effect on ET and TNF-alpha levels and oxidative stress parameters induced by sepsis in experimental rat models. Therefore treatment with CAPE can be used to avoid devastating effects of sepsis.

Endothelin-1 but not Endothelial Nitric Oxide Synthase Gene Polymorphism is Associated with Sickle Cell Disease in Africa

Sickle cell disease shows marked variability in severity and pathophysiology among individuals, probably linked to differential expression of various adhesion molecules. In this study, we investigated the differential distribution, genomic diversity and haplotype frequency of endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1) polymorphisms, recently implicated as important in modification of disease severity. One hundred and forty five sickle cell disease patients (HbSS) and 244 adult and pediatric controls, without sickle cell disease (HbAA), were recruited from Mali. Genotypic analysis of the functionally significant eNOS variants (T786C, G894T and intron 4) and endothelin-1 (G5665T) was carried out with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Our results show that the wild type alleles are the most frequent for all eNOS variants between cases and controls. Allelic and genotypic frequencies of eNOS polymorphic groups are not significantly different between cases and controls (P > 0.05). In addition, there is no association between eNOS variants and sickle cell disease, contrary to published reports. On the other hand, we report that endothelin-1 (G5665T) mutant variant had the lowest allelic frequency, and is significantly associated with sickle cell disease in Africa (P < 0.05). Similarly, haplotype frequencies were the same between cases and controls, except for the haplotype combining all mutant variants (T, C, 4a; P = 0.01). eNOS polymorphic variants are less frequent, with no significance with sickle cell disease in Africa. On the other hand, endothelin-1 is associated with sickle cell disease, and has the capacity to redefine pathophysiology and possibly serve as modulator of disease phenotype.

Endothelin-1 and its role in the pathogenesis of infectious diseases

Endothelins are potent regulators of vascular tone, which also have mitogenic, apoptotic, and immunomodulatory properties (Rubanyi and Polokoff, 1994; Kedzierski and Yanagisawa, 2001; Bagnato et al., 2011). Three isoforms of endothelin have been identified to date, with endothelin-1 (ET-1) being the best studied. ET-1 is classically considered a potent vasoconstrictor. However, in addition to the effects of ET-1 on vascular smooth muscle cells, the peptide is increasingly recognized as a pro-inflammatory cytokine (Teder and Noble, 2000; Sessa et al., 1991). ET-1 causes platelet aggregation and plays a role in the increased expression of leukocyte adhesion molecules, the synthesis of inflammatory mediators contributing to vascular dysfunction. High levels of ET-1 are found in alveolar macrophages, leukocytes (Sessa et al., 1991) and fibroblasts (Gu et al., 1991). Clinical and experimental data indicate that ET-1 is involved in the pathogenesis of sepsis (Tschaikowsky et al., 2000; Goto et al., 2012), viral and bacterial pneumonia (Schuetz et al., 2008; Samransamruajkit et al., 2002), Rickettsia conorii infections (Davi et al., 1995), Chagas disease (Petkova et al., 2000, 2001), and severe malaria (Dai et al., 2012; Machado et al., 2006; Wenisch et al., 1996a; Dietmann et al., 2008). In this minireview, we will discuss the role of endothelin in the pathogenesis of infectious processes.

Endothelin-1 impairs angiogenesis in vitro through Rho-kinase activation after chronic intrauterine pulmonary hypertension in fetal sheep

BACKGROUND

Endothelin-1 (ET-1) and Rho-kinase (ROCK) increase vascular tone in experimental persistent pulmonary hypertension of the newborn (PPHN). Whether ET-1 activates ROCK to decrease angiogenesis in the developing lung remains unknown.

METHODS

Proximal pulmonary artery endothelial cells (PAECs) were harvested from fetal sheep after partial ligation of the ductus arteriosus in utero (PPHN) and controls. Growth and tube formation were assessed after ET-1 treatment. The effect of ET-1 antagonism on tube formation was studied using ET-1 small interfering RNA (siRNA), ET-1 monoclonal antibodies (ET-1mAbs), BQ-123 (an ET(A) blocker), and bosentan (an ET(A)/ET(B) blocker). ET-1 gene and protein and ET(A)/ET(B) receptor protein expression were measured in normal and PPHN PAECs. ET-1-ROCK interactions were assessed by measuring ROCK activity after ET-1, ET-1 siRNA, and bosentan treatments, and tube formation with ET-1 and Y-27632 (ROCK inhibitor).

RESULTS

ET-1 did not affect growth but decreased tube formation in normal and PPHN PAECs. ET-1 protein and gene expression were increased and ET(B) receptor protein decreased in PPHN PAECs. ET-1 siRNA, ET-1mAbs, and bosentan, but not BQ-123, increased tube formation. ROCK activity was increased in PPHN PAECs and decreased with ET-1 siRNA and bosentan treatments. Y-27632 prevented the decrease in tube formation with ET-1.

CONCLUSION

ET-1 activation of ROCK impairs angiogenesis of fetal PAECs. Disruption of ET-1-ROCK interactions may increase vascular growth in PPHN.

Current trends in inflammatory and immunomodulatory mediators in sepsis

Sepsis refers to severe systemic inflammation in response to invading pathogens. An overwhelming immune response, as mediated by the release of various inflammatory mediators, can lead to shock, multiple organ damage, and even death. Cytokines, proteases, lipid mediators, gaseous substances, vasoactive peptides, and cell stress markers play key roles in sepsis pathophysiology. Various adhesion molecules and chemokines sequester and activate neutrophils into the target organs, further augmenting inflammation and tissue damage. Although the anti-inflammatory substances counterbalance proinflammatory mediators, prolonged immune modulation may cause host susceptibility to concurrent infections, thus reflecting enormous challenge toward developing effective clinical therapy against sepsis. To understand the complex interplay between pro- and anti-inflammatory phenomenon in sepsis, there is still an unmet need to study newly characterized mediators. In addition, revealing the current trends of novel mediators will upgrade our understanding on their signal transduction, cross-talk, and synergistic and immunomodulating roles during sepsis. This review highlights the latest discoveries of the mediators in sepsis linking to innate and adaptive immune systems, which may lead to resolution of many unexplored queries.

Endothelin receptor antagonist attenuates oxidative stress in a neonatal sepsis piglet model

BACKGROUND

Oxidative stress (oxidant-antioxidant imbalance) plays an important role in the pathophysiology of neonatal sepsis. This study evaluated whether an antisense peptide endothelin receptor antagonist, ETR-P1/fl, could attenuate oxidative stress in a neonatal sepsis model.

METHODS

A total of 18 3-d-old piglets were anesthetized and mechanically ventilated. Six piglets received cecal ligation and perforation (CLP group) for induction of sepsis. Six piglets also received continuous infusion (0.05 mg/kg/h) of ETR-P1/fl 30 min after CLP (ETR-P1/fl group). Six piglets received a sham operation. Serum total hydroperoxide (TH), biological antioxidant potentials (BAPs), oxidative stress index (OSI, calculated as TH/BAP), interleukin (IL)-6, serum glutamic oxaloacetic transaminase (GOT), and creatinine were measured before CLP and at 1, 3, and 6 h after CLP.

RESULTS

CLP evoked a state of shock resulting in elevated TH, OSI, and IL-6 levels. ETR-P1/fl administration after CLP resulted in lower serum TH at 1 and 3 h after CLP, OSI at 1 and 3 h after CLP, IL-6 at 1 and 3 h after CLP, and GOT at 3 and 6 h after CLP as compared with the CLP group.

CONCLUSION

ETR-P1/fl treatment significantly attenuated the elevation of serum oxidative stress markers (TH and OSI), IL-6, and GOT in a progressive neonatal sepsis CLP model.

Biomarkers of endothelial dysfunction: can they help us deciphering systemic inflammation and sepsis?

The endothelial integrity, as mechanical barrier against microorganisms and as natural "anticoagulant", is crucial for physiologic organ function. Systemic activation of the endothelium upon inflammation, sepsis, and septic shock is always ending in blood-tissue barrier disruption. With increasing dysfunction, uncontrolled clotting activation, capillary microthrombi formation, tissue edema, local hypoxia, and ischemia are initiated. This in turn enhances a vicious circle leading to multiple organ failure and death. Therefore, biomarkers reflecting this special compartment may help in the early detection of systemic inflammation and its complications. This review provides an overview of the most important endothelial biomarkers and their possible use in sepsis.

Combination therapy for life-threatening pulmonary hypertension in a premature infant: first report on bosentan use

Premature infants with preterm premature rupture of membranes (PPROM) are at high risk of severe respiratory failure because of lung hypodysplasia associated with persistent pulmonary hypertension of the newborn (PPHN). We describe the clinical course of a 28-week gestation infant with PPROM from the 20th week and prolonged oligohydramnios before delivery, who developed refractory hypoxia treated with oral bosentan as adjunct therapy to inhaled nitric oxide (iNO) and oral sildenafil. Conclusion Our experience suggests that bosentan can be used in the premature infant with PPHN after PPROM. To the best of our knowledge, this is the first report of bosentan treatment in a premature infant.

Edaravone, a hydroxyl radical scavenger, ameliorates the severity of pulmonary hypertension in a porcine model of neonatal sepsis

Systemic infection in the newborn (neonatal sepsis) is the most common cause of neonatal mortality. Neonatal sepsis is complicated by pulmonary hypertension. In this study, we analyzed the effect of edaravone, a free radical scavenger that is known to reduce the production of inflammatory mediators, such as tumor necrosis factor α (TNFα), on pulmonary hypertension. Experimental and sham groups were drawn from 19 three-day-old piglets; 5 underwent a modified procedure of cecal ligation and perforation (CLP) (CLP group), 8 underwent CLP followed 30 min later by edaravone intravenous administration (edaravone group), and 6 did not undergo CLP and did not receive edaravone (sham group). To evaluate the pulmonary blood pressure despite the sepsis-induced low cardiac output, mean arterial blood pressure (mABP), mean pulmonary arterial pressure (mPAP), and comparative pulmonary hypertension ratio (mPAP/mABP) were determined. Serum TNFα levels were measured before the procedure and at 1, 3, and 6 h after. The mPAP levels were higher in the CLP group at 9 h compared to the edaravone group. The mPAP/mABP ratio was lower in the edaravone and sham groups compared to the CLP group at 6 and 9 h. TNFα in the edaravone and sham groups were lower at 1 and 3 h compared to that in the CLP group. In all animals, mPAP/mABP at 6 h correlated with serum levels of TNFα at 1, 3, and 6 h. These findings suggest that edaravone ameliorates the severity of pulmonary hypertension in a neonatal sepsis model by reducing serum TNFα levels.

Endocrine dysregulation in critically ill foals and horses

Critical illness challenges many endocrine homeostatic systems to overcome diseases, stress, and hostile conditions that threaten survival. Coordinated and consecutive responses by the autonomic nervous system, endocrine metabolic adaptations to mobilize and conserve energy and electrolytes, cardiovascular adjustments to maintain organ perfusion, and immunomodulation to overcome infections and inflammation are required. Because most admissions to equine intensive care units are related to horses with gastrointestinal disease and septic foals, most endocrine information during critical disease are generated from these populations. This article presents an overview on endocrine responses to critical illness in horses and foals and also some comparative information.

Pathophysiology and treatment of septic shock in neonates

Neonatal septic shock is a devastating condition associated with high morbidity and mortality. Definitions for the sepsis continuum and treatment algorithms specific for premature neonates are needed to improve studies of septic shock and assess benefit from clinical interventions. Unique features of the immature immune system and pathophysiologic responses to sepsis, particularly those of extremely preterm infants, necessitate that clinical trials consider them as a separate group. Keen clinical suspicion and knowledge of risk factors will help to identify those neonates at greatest risk for development of septic shock. Genomic and proteomic approaches, particularly those that use very small sample volumes, will increase our understanding of the pathophysiology and direct the development of novel agents for prevention and treatment of severe sepsis and shock in the neonate. Although at present antimicrobial therapy and supportive care remain the foundation of treatment, in the future immunomodulatory agents are likely to improve outcomes for this vulnerable population.

Acute subepicardial infarction associated with severe septic shock--insight in myocardial perfusion

Isolated infarctions of the subepicardial myocardium without changes in subendocardium are extremely rare. We present an autoptic case with an acute subepicardial infarction of the right- and left-ventricular myocardium. A 53-year-old male was admitted to hospital with acute upper abdominal pain. Clinical examination revealed an acute infero-lateral myocardial infarction. The patient succumbed to acute heart failure a few hours later. Autopsy revealed numerous pulmonary abscesses due to suppurative lobular pneumonia with consecutive pericardial effusion. Furthermore, we diagnosed an acute myocardial infarct encompassing the entire right and left ventricles but limited to the subepicardial myocardium only. Microscopically, we observed fibrin microemboli in the subepicardial microvessels. The existence of an isolated subepicardial myocardial infarct challenges our understanding of myocardial perfusion.

Molecular mechanism of mast cell mediated innate defense against endothelin and snake venom sarafotoxin

Mast cells are protective against snake venom sarafotoxins that belong to the endothelin (ET) peptide family. The molecular mechanism underlying this recently recognized innate defense pathway is unknown, but secretory granule proteases have been invoked. To specifically disrupt a single protease function without affecting expression of other proteases, we have generated a mouse mutant selectively lacking mast cell carboxypeptidase A (Mc-cpa) activity. Using this mutant, we have now identified Mc-cpa as the essential protective mast cell enzyme. Mass spectrometry of peptide substrates after cleavage by normal or mutant mast cells showed that removal of a single amino acid, the C-terminal tryptophan, from ET and sarafotoxin by Mc-cpa is the principle molecular mechanism underlying this very rapid mast cell response. Mast cell proteases can also cleave ET and sarafotoxin internally, but such “nicking” is not protective because intramolecular disulfide bridges maintain peptide function. We conclude that mast cells attack ET and sarafotoxin exactly at the structure required for toxicity, and hence sarafotoxins could not “evade” Mc-cpa's substrate specificity without loss of toxicity.

Plasma endothelin-1 levels in septic patients

Dysfunction of the vascular endothelium (ET) causes an increase in serum ET-1 concentration, as observed in septic patients. It was assumed that in this patient population the ET-1 level correlates with the degree of sepsis severity, including the level of organ dysfunction and, in particular, the level of circulatory dysfunction. The aim of the present study was to assess the relationship between levels of ET-1 and levels of N-terminal brain natriuretic propeptide (NT-proBNP), procalcitonin (PCT), and C-reactive protein (CRP), as well as the Sepsis-related Organ Failure Assessment (SOFA) score in septic patients. PCT and CRP were used to estimate the level of sepsis severity; the SOFA score was used to estimate multiorgan dysfunction; and NT-proBNP was used as a marker of cardiac dysfunction. Twenty patients with sepsis and severe sepsis were included in the study. Blood serum ET-1, NT-proBNP, PCT, and CRP concentrations were determined at specific time intervals, and the SOFA score was calculated. Mean ET-1, NT-proBNP, PCT, and CRP concentrations were 8.39 pg/ml +/- 6.39 pg/mL, 140.80 pg/mL +/- 84.65 pg/mL, 22.32 ng/mL +/- 97.41 ng/mL, and 128.51 mg/L +/- 79.05 mg/L, respectively. Correlation between ET-1 levels and levels of NT-proBNP, PCT, and CRP was .3879 (P < .001), .358 (P < .001), and .225 (P = .011), respectively. Mean SOFA score was 6.31 pts +/- 3.75 pts. Correlation between the ET-1 levels and SOFA score was .470 (P < .001). Six patients (30%) died during the observation period of 28 days. ET-1 levels correlate with levels of NT-proBNP, PCT, and CRP, as well as the SOFA score in septic patients.

Endocrine markers of severity and prognosis in critical illness

The cellular processes that unfold in critical illness involve a variety of circulating substances, that may provide clinically relevant insight into the severity and outcome. Among hormonal markers, cortisol, several thyroid-related substances, as well as natriuretic peptides are discussed in this review. Glucose and lipids constitute metabolic markers, the identification and treatment of the former has been of particular importance. Among immune markers, both proinflammatory and anti-inflammatory cytokines, such as interleukin-6, contribute essential prognostic information. Finally, the complement and coagulation pathways also provide unique insight into this complex and heterogeneous process.