Endothelial dysfunction in cirrhosis and portal hypertension

AMPK and the Challenge of Treating Hypoxic Pulmonary Hypertension

Hypoxic pulmonary hypertension (HPH) is characterized by sustained elevation of pulmonary artery pressure produced by vasoconstriction and hyperproliferative remodeling of the pulmonary artery and subsequent right ventricular hypertrophy (RVH). The search for therapeutic targets for cardiovascular pathophysiology has extended in many directions. However, studies focused on mitigating high-altitude pulmonary hypertension (HAPH) have been rare. Because AMP-activated protein kinase (AMPK) is involved in cardiovascular and metabolic pathology, AMPK is often studied as a potential therapeutic target. AMPK is best characterized as a sensor of cellular energy that can also restore cellular metabolic homeostasis. However, AMPK has been implicated in other pathways with vasculoprotective effects. Notably, cellular metabolic stress increases the intracellular ADP/ATP or AMP/ATP ratio, and AMPK activation restores ATP levels by activating energy-producing catabolic pathways and inhibiting energy-consuming anabolic pathways, such as cell growth and proliferation pathways, promoting cardiovascular protection. Thus, AMPK activation plays an important role in antiproliferative, antihypertrophic and antioxidant pathways in the pulmonary artery in HPH. However, AMPK plays contradictory roles in promoting HPH development. This review describes the main findings related to AMPK participation in HPH and its potential as a therapeutic target. It also extrapolates known AMPK functions to discuss the less-studied HAPH context.

Endothelin-1/Nitric Oxide Ratio as a Predictive Factor of Response to Therapy With Terlipressin and Albumin in Patients With Type-1 Hepatorenal Syndrome

Background and Purpose

Predictors of response to type-1 hepatorenal syndrome (HRS) therapy are urgently needed. This study's purpose is to evaluate the proposed predictors in these patients.

Methods

Forty-two type-1 HRS patients with cirrhosis were treated with albumin and terlipressin. Clinical, biochemical, and demographic parameters taken at the onset of therapy and changes in endothelin-1/nitric oxide (ET-1/NO) ratio during therapy were analyzed to check their predictive value.

Results

Response to treatment (serum creatinine level <1.5 mg/dL at the end of therapy) was shown in 20 patients (48%). Independent predictive variables of response to therapy were early reduction of ET-1/NO ratio ≥0.15 at day 3 of therapy and serum bilirubin baseline <8 mg/dL (area under the receiver operating characteristic curve, 0.751; P < 0.001; specificity, 55%; sensitivity, 85%). Response rates in patients with serum bilirubin level <8 and ≥8 mg/dL were 63% and 20%, respectively (P = 0.008). The corresponding values in patients with an early reduction of ET-1/NO ratio ≥0.15 and <0.15 on day 3 were 85% and 13.6%, respectively (P < 0.001).

Conclusions

Early reduction of ET-1/NO ratio and lower serum bilirubin baseline can predict response to type-1 HRS therapy with albumin and terlipressin. Alternative therapy should be investigated for nonresponder type-1 HRS patients.

Vascular syndromes in liver cirrhosis

Liver cirrhosis is associated with multiple vascular syndromes affecting almost all body systems. Many of these syndromes are directly related to impaired liver function and sometimes reversible after liver transplantation while others arise secondary to portal hypertension and ascites. Altered expression of angiogenic and vasoactive compounds (most importantly nitric oxide), endothelial dysfunction, dysregulated neurohormonal control, and systemic inflammatory state play differential roles in mediating homeostatic instability and abnormal vasogenic response. Important vascular features encountered in liver disease include portal hypertension, splanchnic overflow, abnormal angiogenesis and shunts, portopulmonary syndrome, hepatopulmonary syndrome, and systemic hyperdynamic circulation. Redistribution of effective circulatory volume deviating from vital organs and pooling in splanchnic circulation is also encountered in liver patients which may lead to devastating outcomes as hepatorenal syndrome. Etiologically, vascular syndromes are not isolated phenomena and vascular dysfunction in one system may lead to the development of another in a different system. This review focuses on understanding the pathophysiological factors underlying vascular syndromes related to chronic liver disease and the potential links among them. Many of these syndromes are associated with high mortality, thus it is crucial to look for early biomarkers for these syndromes and develop novel preventive and therapeutic strategies.

The Coagulation Profile of End-Stage Liver Disease and Considerations for Intraoperative Management

The coagulopathy of end-stage liver disease results from a complex derangement in both anticoagulant and procoagulant processes. With even minor insults, cirrhotic patients experience either inappropriate bleeding or clotting, or even both simultaneously. The various phases of liver transplantation along with fluid and blood product administration may contribute to additional disturbances in coagulation. Thus, anesthetic management of patients undergoing liver transplantation to improve hemostasis and avoid inappropriate thrombosis in the perioperative environment can be challenging. To add to this challenge, traditional laboratory tests of coagulation are difficult to interpret in patients with end-stage liver disease. Viscoelastic coagulation tests such as thromboelastography (Haemonetics Corporation, Braintree, MA) and rotational thromboelastometry (TEM International, Munich, Germany) have helped to reduce transfusion of allogeneic blood products, especially fresh frozen plasma, but have also lead to the increased use of fibrinogen-containing products. In general, advancements in surgical techniques and anesthetic management have led to significant reduction in blood transfusion requirements during liver transplantation. Targeted transfusion protocols and pharmacologic prevention of fibrinolysis may further aid in the management of the complex coagulopathy of end-stage liver disease.

Aerobic exercise training increases nitrergic innervation function and decreases sympathetic innervation function in mesenteric artery from rats fed a high-fat diet

INTRODUCTION

We investigated whether high-fat diet (HFD)-induced obesity was associated with modifications in mesenteric innervation function, the mechanisms involved, and the possible effects of aerobic exercise training on these changes.

MATERIALS AND METHODS

Male Wistar rats were divided into three groups: rats fed a standard diet (control group); rats fed a HFD (35% fat) for 8 weeks; and HFD rats submitted to aerobic exercise training (8 weeks, 5 times per week for 50  min). Segments of isolated mesenteric arteries were exposed to electric field stimulation (EFS) with or without phentolamine, suramin, or Nω nitro-L-arginine methyl ester. Noradrenaline, ATP, and nitric oxide release, and total and phosphorylated neuronal nitric oxide synthase (nNOS, P-nNOS) expression were also measured.

RESULTS

EFS contraction was greater in sedentary HFD than in control rats. Phentolamine reduced EFS contractions more markedly in HFD rats. Suramin decreased EFS contractions only in control rats. Phentolamine + suramin practically abolished EFS-induced contraction in control rats, whereas it did not modify it in the HFD rats. Noradrenaline release was greater and ATP was lower in HFD rats. Nω nitro-L-arginine methyl ester increased contractions to EFS only in segments from control rats. Nitric oxide release and nNOS and P-nNOS expressions were lower in arterial segments from HFD rats than from control rats. None of these changes in sedentary HFD rats was present in the trained HFD rats.

CONCLUSIONS

Enhanced sympathetic and diminished nitrergic components contributed to increased vasoconstrictor responses to EFS in sedentary HFD rats. All these changes were avoided by aerobic exercise training, suggesting that aerobic exercise could reduce peripheral vascular resistance in obesity.

Endothelial Gab1 deficiency aggravates splenomegaly in portal hypertension independent of angiogenesis

Certain pathological changes, including angiogenesis, actively contribute to the pathogenesis of splenomegaly in portal hypertension (PH), although the detailed molecular and cellular mechanisms remain elusive. In this study, we demonstrated that endothelial Grb-2-associated binder 1 (Gab1) plays a negative role in PH-associated splenomegaly independent of angiogenesis. PH, which was induced by partial portal vein ligation, significantly enhanced Gab1 expression in endothelial cells in a time-dependent manner. Compared with controls, endothelium-specific Gab1 knockout (EGKO) mice exhibited a significant increase in spleen size while their PH levels remained similar. Pathological analysis indicated that EGKO mice developed more severe hyperactive white pulp and fibrosis in the enlarged spleen but less angiogenesis in both the spleen and mesenteric tissues. Mechanistic studies showed that the phosphorylation of endothelial nitric oxide synthase (eNOS) in EGKO mice was significantly lower than in controls. In addition, the dysregulation of fibrosis and inflammation-related transcription factors [e.g., Krüppel-like factor (KLF) 2 and KLF5] and the upregulation of cytokine genes (e.g., TNF-α and IL-6) were observed in EGKO mice. We thus propose that endothelial Gab1 mediates multiple pathways in inhibition of the pathogenesis of splenomegaly in PH via prevention of endothelial dysfunction and overproduction of proinflammatory/profibrotic cytokines.

Selectins and platelet-derived growth factor (PDGF) in schistosomiasis-associated pulmonary hypertension

PURPOSE

The aim of this study was to evaluate the expression profiles of the relevant selectins and PDGF in schistosomiasis-associated pulmonary hypertension.

METHODOLOGY

Patients with three distinct clinical profiles were enrolled in the study: IPAH(n = 11), schistosomiasis-associated PH (Sch-PH))(n = 13), and schistosomiasis without PH (Sch) (n = 13). Healthy volunteers, were recruited as a control group(n = 13). Echocardiography was performed in all groups, and the PH patients underwent right heart catheterization. Plasma soluble adhesion molecules E- and P-Selectin, PDGF-AB, PDGF-BB were determined by ELISA.

RESULTS

E-selectin was significantly increased in the IPAH group compared with the other groups [the control, Sch + PH and Sch groups) (p < 0.001) (Fig. 2)]. P-selectin was lower in Sch (20.2 + 8.9 × 103 pg/mL) as compared to the control, (43 16.8 × 103 pg/mL), IPAH (35.8 7.8 × 103 pg/mL), and Sch + PH (36.8 ± 15.7 × 103 pg/mL) (p = 0.005) groups. Serum PDGF-BB levels were higher in the control group (8.9 ± 4.8 × 103 pg/mL) compared with the IPAH (3.7 ± 2.17 × 103 pg/mL), Sch + PH (5.2 ± 3.7 × 103 pg/mL) and Sch (2.4 ± 1.7 × 103 pg/mL) groups (p < 0.05). PDGF-AB levels were also higher in the control group (25.6 ± 8.6 × 103 pg/mL), compared with the other three groups, being the Sch group the one with lower serum levels of this marker (11.4 ± 8.6 × 103 pg/mL) (p = 0.006).

CONCLUSIONS

In conclusion, vascular inflammation in schistosomiasis, with or without PH, is different from IPAH suggesting distinct pathophysiological mechanisms associated with the development of pulmonary hypertension.

Von Willebrand factor antigen for detection of hepatopulmonary syndrome in patients with cirrhosis

BACKGROUND & AIMS

Hepatopulmonary syndrome (HPS) occurs in 20-30% of patients with liver cirrhosis and is associated with a >2 fold increased mortality. Endothelial dysfunction seems to play a central role in its pathogenesis. von Willebrand factor antigen (vWF-Ag), an established marker of endothelial dysfunction, is significantly elevated in patients with liver cirrhosis, portal hypertension, and in experimental HPS. Aim of the present study was to evaluate the impact of vWF-Ag as a screening marker for presence of HPS in patients with stable cirrhosis.

METHODS

145 patients with stable liver cirrhosis were screened for presence of HPS in this prospective cohort type cross sectional diagnostic study. vWF-Ag and SaO2 levels were assessed at time of screening for HPS. Criteria of HPS were fulfilled in 31 (21%) patients.

RESULTS

vWF-Ag levels were significantly higher in patients with HPS compared to patients without HPS (p<0.001). Furthermore, vWF-Ag correlated significantly with gas exchange in HPS positive patients (p<0.05). vWF-Ag is an independent predictor of HPS after correction for sex, age, model for endstage-liver disease (MELD), and hepatic venous pressure gradient (HVPG) (OR per 1% increase of vWF-Ag: 1.02, 95% CI: 1.00-1.04, p<0.05). The best cut-off was 328% at a sensitivity of 100% and specificity of 53.5%; positive predictive value: 36.9%; negative predictive value: 100%.

CONCLUSIONS

HPS is associated with elevated vWF-Ag levels. vWF-Ag may be a useful screening tool for early detection of HPS. Further studies investigating vWF-Ag in HPS will be needed to confirm our findings.

Tranilast increases vasodilator response to acetylcholine in rat mesenteric resistance arteries through increased EDHF participation

Background and Purpose

Tranilast, in addition to its capacity to inhibit mast cell degranulation, has other biological effects, including inhibition of reactive oxygen species, cytokines, leukotrienes and prostaglandin release. In the current study, we analyzed whether tranilast could alter endothelial function in rat mesenteric resistance arteries (MRA).

Experimental Approach

Acetylcholine-induced relaxation was analyzed in MRA (untreated and 1-hour tranilast treatment) from 6 month-old Wistar rats. To assess the possible participation of endothelial nitric oxide or prostanoids, acetylcholine-induced relaxation was analyzed in the presence of L-NAME or indomethacin. The participation of endothelium-derived hyperpolarizing factor (EDHF) in acetylcholine-induced response was analyzed by preincubation with TRAM-34 plus apamin or by precontraction with a high K⁺ solution. Nitric oxide (NO) and superoxide anion levels were measured, as well as vasomotor responses to NO donor DEA-NO and to large conductance calcium-activated potassium channel opener NS1619.

Key Results

Acetylcholine-induced relaxation was greater in tranilast-incubated MRA. Acetylcholine-induced vasodilation was decreased by L-NAME in a similar manner in both experimental groups. Indomethacin did not modify vasodilation. Preincubation with a high K⁺ solution or TRAM-34 plus apamin reduced the vasodilation to ACh more markedly in tranilast-incubated segments. NO and superoxide anion production, and vasodilator responses to DEA-NO or NS1619 remained unmodified in the presence of tranilast.

Conclusions and Implications

Tranilast increased the endothelium-dependent relaxation to acetylcholine in rat MRA. This effect is independent of the nitric oxide and cyclooxygenase pathways but involves EDHF, and is mediated by an increased role of small conductance calcium-activated K+ channels.

Endothelin-1 activation of the endothelin B receptor modulates pulmonary endothelial CX3CL1 and contributes to pulmonary angiogenesis in experimental hepatopulmonary syndrome

Hepatic production and release of endothelin-1 (ET-1) binding to endothelin B (ETB) receptors, overexpressed in the lung microvasculature, is associated with accumulation of pro-angiogenic monocytes and vascular remodeling in experimental hepatopulmonary syndrome (HPS) after common bile duct ligation (CBDL). We have recently found that lung vascular monocyte adhesion and angiogenesis in HPS involve interaction of endothelial C-X3-C motif ligand 1 (CX3CL1) with monocyte CX3C chemokine receptor 1 (CX3CR1), although whether ET-1/ETB receptor activation influences these events is unknown. Our aim was to define if ET-1/ETB receptor activation modulates CX3CL1/CX3CR1 signaling and lung angiogenesis in experimental HPS. A selective ETB receptor antagonist, BQ788, was given for 2 weeks to 1-week CBDL rats. ET-1 (±BQ788) was given to cultured rat pulmonary microvascular endothelial cells overexpressing ETB receptors. BQ788 treatment significantly decreased lung angiogenesis, monocyte accumulation, and CX3CL1 levels after CBDL. ET-1 treatment significantly induced CX3CL1 production in lung microvascular endothelial cells, which was blocked by inhibitors of Ca(2+) and mitogen-activated protein kinase (MEK)/ERK pathways. ET-1-induced ERK activation was Ca(2+) independent. ET-1 administration also increased endothelial tube formation in vitro, which was inhibited by BQ788 or by blocking Ca(2+) and MEK/ERK activation. CX3CR1 neutralizing antibody partially inhibited ET-1 effects on tube formation. These findings identify a novel mechanistic interaction between the ET-1/ETB receptor axis and CX3CL1/CX3CR1 in mediating pulmonary angiogenesis and vascular monocyte accumulation in experimental HPS.

Crosstalk between fibroblasts and inflammatory cells

Fibroblasts, which are traditionally recognized as a quiescent cell responsible for extracellular matrix production, are more and more appreciated as an active key player of the immune system. This review describes how fibroblasts and immune cells reciprocally influence the pathogenesis of fibrosis. An overview is given how fibroblasts are triggered by components of the innate and adaptive immunity on the one hand and how fibroblasts modulate immune cell behaviour via conditioning the cellular and cytokine microenvironment on the other hand. Finally, latest insights into the role of cardiac fibroblasts in the orchestration of inflammatory cell infiltration in the heart, and their impact on heart failure, are outlined.

Characteristic of PGDS potential regulation role on spermatogenesis in the Chinese mitten crab Eriocheir sinensis

Prostaglandin D synthase (PGDS) catalyzes the isomerization of PGH2 to produce PGD2 in the presence of sulfhydryl compounds. In this study, a full length PGDS gene comprising 1250 nucleotides from the Chinese mitten crab Eriocheir sinensis (Es-PGDS) was characterized, with a 615 bp open reading frame encoding 204 amino acid residues. Its deduced peptide has high homology with other species' PGDS protein. The Es-PGDS mRNA expression was tissue-related, with the highest expression observed in the hepatopancreas, accessory sex gland, testis and ovaries. We also detected the different stages of tissue expression and the enzyme activity for Es-PGDS in the testis and male crab hepatopancreas. The different expression patterns and its corresponding enzyme activity level indicated that PGDS is involving in the regulation of reproductive action during the period of rapid development in E. sinensis. Furthermore our research could arouse a heat debate on the PGDS reproductive function in invertebrate and further study will be needed to determine the molecular mechanism(s) linking PGDS functions to spermatogenesis and ontogenesis if this gene is to be exploited as a molecular biomarker in further studies of development.

Increased mortality with peptic ulcer bleeding in patients with both compensated and decompensated cirrhosis

BACKGROUND

Cirrhosis is associated with worse outcomes in peptic ulcer bleeding (PUB). There are no population-based studies from the United States on the impact of cirrhosis on PUB outcomes.

OBJECTIVE

To investigate the impact of cirrhosis on outcomes of patients with PUB.

DESIGN

Cross-sectional study.

SETTING

Nationwide Inpatient Sample 2009.

PATIENTS

International Classification of Diseases, the 9th revision, codes were used to identify patients with PUB and cirrhosis. The control group was patients with PUB without cirrhosis.

MAIN OUTCOME MEASUREMENTS

In-hospital mortality, length of stay, and hospitalization costs.

RESULTS

A total of 96,887 discharges with PUB as a diagnosis were identified-3574 with PUB and cirrhosis and 93,313 with PUB alone without cirrhosis. Mortality of PUB with concomitant cirrhosis was higher than in the control group without cirrhosis (5.5% vs 2%; P = .01); decompensated cirrhosis had higher mortality than did compensated cirrhosis (6.6% vs 3.9%; P = .01). In multivariate analysis, the presence of cirrhosis independently increased mortality (adjusted odds ratio (aOR) 3.3; 95% confidence interval [CI], 2.2-4.9). Stratified analysis showed that decompensated cirrhosis (aOR 4.4; 95% CI, 2.6-7.3) had higher mortality than compensated cirrhosis (aOR 1.9; 95% CI, 1.04-3.6). There was no difference in the proportion of patients who underwent endoscopy within 24 hours (51.9% vs 51.1%; P = .68) between those with cirrhosis and controls. Patients with cirrhosis received less surgical intervention (aOR 0.8; 95% CI, 0.6-0.9) compared with controls. Hospitalization costs also were increased in patients with decompensated cirrhosis.

LIMITATIONS

Administrative data set.

CONCLUSION

Both decompensated and compensated cirrhosis are associated with increased mortality in patients with PUB.

Hemostasis in liver disease: implications of new concepts for perioperative management

The hemostatic profile of patients with liver diseases is frequently profoundly different from that of healthy individuals. These complex alterations lead to abnormal results from routine laboratory tests, but because of the nature of these assays, they fail to accurately represent the patient's hemostatic state. Nevertheless, based on abnormal laboratory coagulation values, it has long been assumed that patients with liver disease have a natural bleeding tendency and are protected from thrombosis. This assumption is false; the average patient with liver disease is actually in a state of "rebalanced hemostasis" that can relatively easily be tipped toward both bleeding and thrombosis. The new paradigm of rebalanced hemostasis has strong implications for the clinic, which are presented in this review. There is no evidence that prophylactic transfusion of plasma helps to prevent procedure-related bleeding. In addition, the presence of independent risk factors such as poor kidney status or infections should be carefully assessed before invasive procedures. Furthermore, central venous pressure plays an important role in the risk of bleeding in patients with liver diseases, so during procedures, a restrictive infusion policy should be applied. Finally, thrombosis prophylaxis should not be withheld from patients with cirrhosis or acute liver failure, and clinicians should be alert to the possibility of thrombosis occurring in these patients.

Changes in ultrastructure and biomechanical properties of the portal vein in rats with intrahepatic portal hypertension

AIM: To observe the ultrastructure and biomechanical properties of the portal vein in rats with intrahepatic portal hypertension to provide an experimental basis for further exploring the pathogenesis of portal hypertension.

METHODS: Subcutaneous injection of carbon tetrachloride was performed to induce intrahepatic portal hypertension in rats. Biomechanical methods were used to determine portal vein diameter, longitudinal tensile stress-strain curve and the size of the residual stress during portal hypertension formation. Portal vein ultrastructure was observed by electron microscopy.

RESULTS: Compared with normal rats, the portal vein diameter was significantly greater in rats with portal hypertension (1.53 ± 0.28 mm vs 1.14 ± 0.17 mm, P < 0.01); portal vein ultrastructure changed significantly; longitudinal tensile stress - strain curve was steeper; the time consumed for the whole process of tensile strain was shorter; the stress at 50% strain was significantly larger (1.04 ± 0.13 N vs 0.51 ± 0.08 N, P < 0.01); the opening angle of the portal vein and arc fluctuations increased significantly (110.34碍 ± 8.09碍 vs 79.93碍 ± 2.44碍, P < 0.01).

CONCLUSION: Rats with intrahepatic portal hypertension have abnormal portal vein wall remodeling, decreased portal vein compliance, and changes in circumferential and axial biomechanical characteristics.

Opposite effect of mast cell stabilizers ketotifen and tranilast on the vasoconstrictor response to electrical field stimulation in rat mesenteric artery

OBJECTIVES

We analyzed whether mast cell stabilization by either ketotifen or tranilast could alter either sympathetic or nitrergic innervation function in rat mesenteric arteries.

METHODS

Electrical field stimulation (EFS)-induced contraction was analyzed in mesenteric segments from 6-month-old Wistar rats in three experimental groups: control, 3-hour ketotifen incubated (0.1 αmol/L), and 3-hour tranilast incubated (0.1 mmol/L). To assess the possible participation of nitrergic or sympathetic innervation, EFS contraction was analyzed in the presence of non-selective nitric oxide synthase (NOS) inhibitor L-NAME (0.1 mmol/L), α-adrenergic receptor antagonist phentolamine (0.1 µmol/L), or the neurotoxin 6-hydroxydopamine (6-OHDA, 1.46 mmol/L). Nitric oxide (NO) and superoxide anion (O2.(-) levels were measured, as were vasomotor responses to noradrenaline (NA) and to NO donor DEA-NO, in the presence and absence of 0.1 mmol/L tempol. Phosphorylated neuronal NOS (P-nNOS) expression was also analyzed.

RESULTS

EFS-induced contraction was increased by ketotifen and decreased by tranilast. L-NAME increased the vasoconstrictor response to EFS only in control segments. The vasodilator response to DEA-NO was higher in ketotifen- and tranilast-incubated segments, while tempol increased vasodilator response to DEA-NO only in control segments. Both NO and O2(-) release, and P-nNOS expression were diminished by ketotifen and by tranilast treatment. The decrease in EFS-induced contraction produced by phentolamine was lower in tranilast-incubated segments. NA vasomotor response was decreased only by tranilast. The remnant vasoconstriction observed in control and ketotifen-incubated segments was abolished by 6-OHDA.

CONCLUSION

While both ketotifen and tranilast diminish nitrergic innervation function, only tranilast diminishes sympathetic innnervation function, thus they alter the vasoconstrictor response to EFS in opposing manners.

Functional variants of eNOS and iNOS genes have no relationship to the portal hypertension in patients with liver cirrhosis

OBJECTIVE

Nitric oxide is an important vasoactive mediator. Changes in NO production, caused by functional variants of both endothelial and inducible NO synthase (eNOS, iNOS), might play a role in portal hypertension. The aim was to study the significance of functional eNOS and iNOS gene variants in cirrhotic patients and their interrelationship to both inflammatory and endothelial activation parameters.

MATERIAL AND METHODS

One hundred and thirty-two patients with liver cirrhosis (age 36-72 years) and 101 controls were examined for functional variants of eNOS (E298D, 27bpintr4, 786T/C) and iNOS (R221W, S608L) genes. Inflammatory (IL6, IL8, IL10) and vasoactive (sVCAM-1, E-selectin) cytokines were measured using ELISA kits.

RESULTS

The frequency of E298D (GG 12%, GT 41%, TT 47%), 28bpintr4 (AA 6%, AB 28%, BB 66%), 786T/C genotypes (CC 17%, CT 45%, TT 38%), as well as R221W (CC 93%, CT 7%, TT 0%), and S608L (CC 65%, CT 32%, TT 3%) genotypes in cirrhotic patients did not differ from the controls (p > 0.05 for all comparisons). No relationship was found between the frequency of these genotypes and the severity of portal hypertension, or either inflammatory or vasoactive cytokines. A positive correlation was found between hepatic venous pressure gradient and cytokine concentration: sVCAM-1, IL6, IL8, IL10.

CONCLUSIONS

Examined eNOS and iNOS variants have no relationship to pathogenesis of liver cirrhosis. Severity of portal hypertension was associated with the changes in endothelial activation.

Association between plasma cyclic guanosine monophosphate levels and hemodynamic instability during liver transplantation

The activation of cyclic guanosine monophosphate (cGMP) production in patients with end-stage liver disease (ESLD) has been associated with hemodynamic instability during orthotopic liver transplantation (OLT). The aim of this prospective, observational study was to investigate the involvement of cGMP in the mediation of profound hypotension during liver graft reperfusion. An additional objective was to determine whether preoperative cGMP levels are associated with intraoperative hemodynamic instability. Forty-four consecutive patients undergoing OLT were included in the study. Blood samples for cGMP analysis were obtained from (1) the radial artery before the surgical incision; (2) the radial artery, portal vein, and flush blood during the anhepatic phase; and (3) the radial artery 20 minutes after liver graft reperfusion. On the basis of a statistical analysis, the patients were divided into 2 groups: group 1 (preoperative cGMP level ≥ 0.05 μmol/L) and group 2 (preoperative cGMP level < 0.05 μmol/L). We demonstrated a significant correlation between the preoperative levels of cGMP and the amount of catecholamine required to maintain hemodynamic stability during reperfusion (r = 0.52, P < 0.001), the length of the hospital stay (r = 0.38, P = 0.01), and the length of the intensive care unit (ICU) stay (r = 0.44, P = 0.004). We also demonstrated a significantly higher intraoperative catecholamine requirement (P < 0.001) and a prolonged postoperative ICU stay (P = 0.02) in group 1 patients versus group 2 patients. In conclusion, this study demonstrates increased baseline cGMP production in patients with ESLD, which is significantly associated with severe hypotension during OLT. We suggest that preoperative levels of cGMP correlate with hemodynamic instability during liver graft reperfusion.

Nitric oxide and prostaglandin as mediators in the pathogenesis of hyperkinetic circulatory state in a model of endotoxemia-induced portal hypertension

AIMS

To evaluate the participation of nitric oxide (NO) and prostaglandin (PGI2) on hyperdynamic state in endotoxemia-induced portal hypertension (EIP) induced by chronic endotoxemia.

METHODS

The portal pressure (PP) and mean arterial pressure (MAP) were recorded, in vivo before and after administration of L-NAME (NOS inhibitor) and indomethacin (specific blocker of COX). The vasoactive responses to acetylcholine of thoracic rat aortic rings were studied in vitro before and after nitric oxide and cyclooxygenase blockade using multichannel organ bath. The mRNA expression for isoforms of (cyclooxygenase) COX and nitric oxide synthase (NOS) were analyzed using RT-PCR.

RESULTS

Administration of both L-NAME and indomethacin in EIP rabbits significantly reduced (p < 0.05) the PP and reversed the MAP to normal as compared to sham-operated (SO) rabbits. There was impaired vasodilatory response to acetylcholine in EIP rabbits. L-NAME caused a significant reduction in acetylcholine-induced vasorelaxation in SO rabbits than EIP due to preexisting hyperemia in EIP. Indomethacin partially restored vasoresponsiveness to acetylcholine in EIP group. The mRNA expression of eNOS (endothelial NOS) and COX-1 (constitutive COX) were significantly higher in SO than EIP rabbits. iNOS (inducible NOS) and COX-2 (inducible COX) mRNA expression was seen only in EIP rabbits.

CONCLUSIONS

A significant component of acetylcholine-mediated vasorelaxation in EIP model is modulated by eNOS. There was increased production of contractile prostaglandin in EIP rabbits. iNOS and COX-2 play an important role in the hemodynamic abnormalities of PHT. This novel model of PHT produced by chronic splanchnic endotoxemia in rabbit, mimics impaired vasodilation and vasoreactivity akin to other models of PHT.

Long-term risk of recurrent peptic ulcer bleeding in patients with liver cirrhosis: a 10-year nationwide cohort study

Peptic ulcer bleeding leads to substantial morbidity and mortality in patients with liver cirrhosis, but their long-term risk of recurrent bleeding remains elusive. This nationwide cohort study aimed to elucidate the association between cirrhosis and recurrent peptic ulcer bleeding by analyzing the Taiwan National Health Insurance Research Database. We enrolled a total of 9,711 patients who had cirrhosis with clinical complications of portal hypertension from all patients (n = 271,030) hospitalized for peptic ulcer bleeding between January 1997 and December 2006, along with 38,844 controls who were matched at a 1:4 proportion for age, sex, and antisecretory agents. We accounted for death as the competing cause of risk when calculating the cumulative incidences and hazard ratios of recurrent bleeding during the 10-year study period. Overall, patients with cirrhosis had a significantly higher death-adjusted rebleeding rate compared with controls (1 year, 14.4% versus 11.3%; 5 years, 26.1% versus 22.5%; 10 years, 28.4% versus 27.1%; P < 0.001). The modified Cox proportional hazard model verified that cirrhosis was significantly associated with peptic ulcer rebleeding (adjusted hazard ratio, 3.19; 95% confidence interval, 2.62-3.88), but also uncovered a seemingly paradoxical interaction between cirrhosis and age. Multivariate stratified analysis further revealed that the rebleeding risk after adjustment for death diminished with age in patients with cirrhosis, whose risk of death far exceeded that of rebleeding when they grew old.

CONCLUSION

Liver cirrhosis is associated with long-term risk of recurrent peptic ulcer bleeding, although the risk declines with age because of death being the competing cause. Effective therapy should be sought to reduce this excessive risk in these critically ill patients, particularly for those at younger age with longer life expectancy.

Coagulation in hepatobiliary disease

OBJECTIVE

To review the pathogenesis and clinical consequences of coagulation abnormalities accompanying hepatobiliary disorders and to highlight the need for further studies to characterize these derangements and their treatment options in small animal patients.

DATA SOURCES

Veterinary and human medical literature: original research articles, scientific reviews, consensus statements, and recent texts.

SUMMARY

The liver plays an important role in the production and clearance of many components of coagulation. A wide range of hemostatic derangements can occur in patients with hepatobiliary disease including alterations in platelet number and function, coagulation factor levels, anticoagulants, vascular endothelial function, and fibrinolysis. As these hemostatic alterations include both pro- and anticoagulation pathways, the net result is often a rebalanced hemostatic system that can be easily disrupted by concurrent conditions resulting in either clinical bleeding or thrombosis. Conventional coagulation tests are inadequate at identifying the spectrum of coagulation alterations occurring in patients with hepatobiliary disease, but their evaluation is necessary to assess bleeding risk and provide prognostic information. A paucity of information exists regarding the treatment of the coagulation derangements in small animals with hepatobiliary disease. Extrapolation from human studies provides some information about potential treatment options, but further studies are warranted in this area to elucidate the best management for coagulation abnormalities in dogs and cats with hepatobiliary disease.

CONCLUSION

Hepatobiliary disease can have profound effects on coagulation function leading to hypercoagulable or hypocoagulable states. Overall coagulation status with hepatobiliary disease depends on both the type and severity of disease and the presence of associated complications.

Effect of melatonin and misoprostol on bacterial translocation in portal hypertensive rats

BACKGROUND AND AIM

Portal hypertension is the main complication of cirrhosis and it is responsible for its most common complications. Bacterial translocation increases the morbidity and mortality rates in patients with portal hypertension. We aimed to investigate the effects of melatonin and misoprostol on bacterial translocation induced by portal hypertension.

METHODS

We established four groups, each containing eight rats. Except for the control and sham groups, the animals in the other groups (treatment groups) received misoprostol or melatonin for 3 days after the first operation. In the sham group, a laparotomy was carried out and only the portal vein was dissected. Calibrated portal vein ligation was carried out in the other groups. All animals were given 10(10) Escherichia coli by orogastric intubation 12 h before sampling. Seventy-two hours after the first operation, mesenteric lymph node and blood samples were obtained and cultured. Two cc blood samples were obtained for a polymerase chain reaction study. A piece of terminal ileum was also sampled for histopathologic examination.

RESULTS

Mesenteric lymph node and blood cultures of all control animals were positive for microbiological growth, and polymerase chain reaction results were positive in seven of the eight rats. Histopathologically, edema, vasodilatation and inflammatory cell infiltration were found to be less in the other groups in comparison to the control group. The incidence of bacterial translocation was decreased in all treatment groups as compared to the control group.

CONCLUSIONS

In this study, bacterial translocation occurred in portal hypertension. Melatonin and misoprostol reduced the incidence of bacterial translocation in portal hypertensive rats.

Nitroglycerine effects on portal vein mechanics and oxidative stress in portal hypertension

AIM: Тo examine the effects of nitroglycerine on portal vein haemodynamics and oxidative stress in patients with portal hypertension.

METHODS: Thirty healthy controls and 39 patients with clinically verified portal hypertension and increased vascular resistance participated in the study. Liver diameters, portal diameters and portal flow velocities were recorded using color flow imaging/pulsed Doppler detection. Cross-section area, portal flow and index of vascular resistance were calculated. In collected blood samples, superoxide anion radical (O₂^-), hydrogen peroxide (H₂O₂), index of lipid peroxidation (measured as TBARS) and nitric oxide (NO) as a marker of endothelial response (measured as nitrite-NO₂^-) were determined. Time-dependent analysis was performed at basal state and in 10th and 15th min after nitroglycerine (sublingual 0.5 mg) administration.

RESULTS: Oxidative stress parameters changed significantly during the study. H₂O₂ decreased at the end of study, probably via O₂^- mediated disassembling in Haber Weiss and Fenton reaction; O₂^- increased significantly probably due to increased diameter and tension and decreased shear rate level. Consequently O₂^- and H₂O₂ degradation products, like hydroxyl radical, initiated lipid peroxidation. Increased blood flow was to some extent lower in patients than in controls due to double paradoxes, flow velocity decreased, shear rate decreased significantly indicating non Newtonian characteristics of portal blood flow.

CONCLUSION: This pilot study could be a starting point for further investigation and possible implementation of some antioxidants in the treatment of portal hypertension.

Management of coagulopathy in patients with decompensated liver cirrhosis

Patients with decompensated liver cirrhosis have significantly impaired synthetic function. Many proteins involved in the coagulation process are synthesized in the liver. Routinely performed tests of the coagulation are abnormal in patients with decompensated liver cirrhosis. This has led to the widespread belief that decompensated liver cirrhosis is prototype of acquired hemorrhagic coagulopathy. If prothrombin time is prolonged more than 3 seconds over control, invasive procedures like liver biopsy, splenoportogram, percutaneous cholangiography, or surgery were associated with increased risk of bleeding, and coagulopathy should be corrected with infusion of fresh frozen plasma. These practices were without any scientific evidence and were associated with significant hazards of fresh frozen plasma transfusion. Now, it is realized that coagulation is a complex process involving the interaction of procoagulation and anticoagulation factors and the fibrinolytic system. As there is reduction in both anti and procoagulant factors, global tests of coagulation are normal in patients with acute and chronic liver disease indicating that coagulopathy in liver disease is more of a myth than a reality. In the last few years, surgical techniques have substantially improved, and complex procedures like liver transplantation can be done without the use of blood or blood products. Patients with liver cirrhosis may also be at increased risk of thrombosis. In this paper, we will discuss coagulopathy, increased risk of thrombosis, and their management in decompensated liver cirrhosis.

Beneficial effect of ultra-low-dose aspirin in platelet activity alterations and haemorrhage observed in experimental portal hypertension

Ultra-low-dose aspirin has shown a prothrombotic effect in the laser-induced thrombosis model. Several studies of our laboratory have shown a positive effect in rats with two different experimental models of portal hypertension: portal vein ligation, a model with an almost normal liver, and 30 days of bile duct ligation, a model with cirrhosis and presence of ascitis. In both models of portal hypertensive rats, bleeding time was prolonged and thrombi formation, in a laser-induced model of thrombi production, decreased. The hypotheses of the presented studies were that ultra-low-dose aspirin could decrease the bleeding complications in these models and that the mechanism for these effects could act thorough the COX pathway. In different studies, ultra-low dose of aspirin normalized the induced hemorrhage time, thrombi production, and platelet-endothelial cell interaction. The possible beneficial role of these doses of aspirin and mechanism of COX 2 inhibition are discussed.

Elevated levels of circulating angiotensin converting enzyme in patients with hepatoportal sclerosis

BACKGROUND AND AIMS

Hepatoportal sclerosis (HPS) is a clinicopathologic condition that is clinically characterized by portal hypertension (varices and portosystemic collateral vessels), splenomegaly and pancytopenia, in the absence of cirrhosis. Although the etiology is obscure, a number of theories such as immunologic and vascular endothelial cellular abnormalities have been put forward to explain the underlying pathophysiology. Angiotensin-converting enzyme (ACE), an important molecule of the renin-angiotensin system (RAS), is also known as a regulatory molecule in systemic and portal circulation in distinct disorders. The aim of the present study was to investigate the possible role of the ACE in the context of RAS in HPS pathogenesis.

MATERIALS AND METHODS

The study was conducted on 30 HPS patients (16 men, 14 women; median age 36 years, range 18-63) and 20 healthy controls. The clinical features of HPS patients including demographics, laboratory, and ultrasonography findings were summarized. Serum ACE levels were measured by using commercially available kits.

RESULTS

Serum median ACE levels were 36 (8-174) U/l and 16 (8-43) U/l for the HPS patients and controls, respectively. Serum ACE levels were significantly higher in patients with HPS compared to the control group (P < 0.05).

CONCLUSION

ACE in the context of RAS may be associated with pathological endothelial occlusive events in the microenvironment of the portal circulation in HPS. Revealing the interactions between circulating and local RAS within the hepatic microenvironment would enlighten the biologic basis and clinical management of liver diseases.

Management of coagulopathy in patients with decompensated liver cirrhosis

Patients with decompensated liver cirrhosis have significantly impaired synthetic function. Many proteins involved in the coagulation process are synthesized in the liver. Routinely performed tests of the coagulation are abnormal in patients with decompensated liver cirrhosis. This has led to the widespread belief that decompensated liver cirrhosis is prototype of acquired hemorrhagic coagulopathy. If prothrombin time is prolonged more than 3 seconds over control, invasive procedures like liver biopsy, splenoportogram, percutaneous cholangiography, or surgery were associated with increased risk of bleeding, and coagulopathy should be corrected with infusion of fresh frozen plasma. These practices were without any scientific evidence and were associated with significant hazards of fresh frozen plasma transfusion. Now, it is realized that coagulation is a complex process involving the interaction of procoagulation and anticoagulation factors and the fibrinolytic system. As there is reduction in both anti and procoagulant factors, global tests of coagulation are normal in patients with acute and chronic liver disease indicating that coagulopathy in liver disease is more of a myth than a reality. In the last few years, surgical techniques have substantially improved, and complex procedures like liver transplantation can be done without the use of blood or blood products. Patients with liver cirrhosis may also be at increased risk of thrombosis. In this paper, we will discuss coagulopathy, increased risk of thrombosis, and their management in decompensated liver cirrhosis.

Paediatric cholestatic liver disease: Diagnosis, assessment of disease progression and mechanisms of fibrogenesis

Cholestatic liver disease causes significant morbidity and mortality in children. The diagnosis and management of these diseases can be complicated by an inability to detect early stages of fibrosis and a lack of adequate interventional therapy. There is no single gold standard test that accurately reflects the presence of liver disease, or that can be used to monitor fibrosis progression, particularly in conditions such as cystic fibrosis. This has lead to controversy over how suspected liver disease in children is detected and diagnosed. This review discusses the challenges in using commonly available methods to diagnose hepatic fibrosis and monitor disease progression in children with cholestatic liver disease. In addition, the review examines the mechanisms hypothesised to be involved in the development of hepatic fibrogenesis in paediatric cholestatic liver injury which may ultimately aid in identifying new modalities to assist in both disease detection and therapeutic intervention.

Rebalanced hemostasis in patients with liver disease: evidence and clinical consequences

Patients with liver disease frequently acquire a complex disorder of hemostasis secondary to their disease. Routine laboratory tests such as the prothrombin time and the platelet count are frequently abnormal and point to a hypocoagulable state. With more sophisticated laboratory tests it has been shown that patients with liver disease may be in hemostatic balance as a result of concomitant changes in both pro- and antihemostatic pathways. Clinically, this rebalanced hemostatic system is reflected by the large proportion of patients with liver disease who can undergo major surgery without any requirement for blood product transfusion. However, the hemostatic balance in the patient with liver disease is relatively unstable as evidenced by the occurrence of both bleeding and thrombotic complications in a significant proportion of patients. Although it is still common practice to prophylactically correct hemostatic abnormalities in patients with liver disease before invasive procedures by administration of blood products guided by the prothrombin time and platelet count, we believe that this policy is not evidence-based. In this article, we will provide arguments against the traditional concept that patients with liver failure have a hemostasis-related bleeding tendency. Consequences of these new insights for hemostatic management will be discussed.

Sorafenib attenuates the portal hypertensive syndrome in partial portal vein ligated rats

BACKGROUND/AIMS

Angiogenesis plays a key role in development of portal hypertension (PHT) and represents a potential therapeutic target. We aimed to evaluate the molecular effects of sorafenib, a multiple tyrosine kinase inhibitor, on splanchnic hemodynamics in rats with partial portal vein ligation (PPVL).

METHODS

The following four groups of rats were treated orally with sorafenib (10mg/kg per day; SORA group) or placebo (PLAC group) for 7 days, beginning at the day of PPVL or sham operation (SO): (1) PPVL-SORA, (2) PPVL-PLAC, (3) SO-SORA and (4) SO-PLAC. Measurements of mean arterial pressure (MAP), portal pressure (PP), and superior mesenterial artery blood flow (SMABF) were performed. Portosystemic collateral blood flow (PSCBF) was determined by radioactive microspheres. Splanchnic protein expression of CD31, alpha-smooth muscle actin (alphaSMA), phospho-extracellular signal-regulated kinase (pERK), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), tumor necrosis factor alpha (TNFalpha), and endothelial nitric oxide synthetase (eNOS) was assessed by Western blot. Gene expression was studied by angiogenesis-focused real-time reverse transcription polymerase chain reaction microarray.

RESULTS

PP, SMABF, and PSCBF were significantly higher in PPVL rats than in SO rats. MAP and heart rate were similar in all groups. Treatment with sorafenib resulted in a significant decrease of PP (p<0.001) and SMABF (p<0.05) in PPVL-SORA rats compared to PPVL-PLAC rats. PPVL-SORA rats had markedly less PSCBF than PPVL-PLAC rats (p<0.001). Superior mesenteric artery resistance (SMAR) was significantly lower in both PPVL groups compared to both SO groups, but PPVL-SORA rats showed significantly higher SMAR than PPVL-PLAC rats (p<0.05). The increased protein expression of CD31, alphaSMA, pERK, VEGF, PDGF, TNFalpha, and eNOS in rats with PHT was markedly decreased by sorafenib treatment. Sorafenib decreased mRNA levels of TNFalpha, VEGF receptor 2, VEGF receptor 1, transforming growth factor beta, cyclooxygenase 1, and expression of various genes that are involved in pathways of cellular proliferation, fibrogenesis, tissue remodeling, inflammation, and angiogenesis.

CONCLUSIONS

Treatment with sorafenib reduced PP, SMABF, and PSCBF in noncirrhotic rats with prehepatic PHT, without affecting systemic hemodynamics. Additional antiproliferative, anti-inflammatory, and antiangiogenic effects of sorafenib were identified.

Influence of liver cirrhosis on the pharmacokinetics, pharmacodynamics, and safety of tezosentan

This study investigates the pharmacokinetics, pharmacodynamics, and safety of the parenteral endothelin receptor antagonist tezosentan in patients with Child-Pugh classification B/C liver impairment. Cohorts I and II consist of 5 and 11 patients, respectively, with low serum bilirubin (<or=3.0 mg/dL) who receive intravenous tezosentan at 0.2 mg/h for 24 hours followed by 1.0 mg/h for 24 hours (cohort I) or 1.0 mg/h for 24 hours followed by 5.0 mg/h for 24 hours (cohort II). Cohort III (5 patients) receives the same treatment as cohort II but patients have high serum bilirubin (3.5-12 mg/dL). Each cohort includes 1 or 2 placebo patients (in total 4 patients). Compared with a historical control group of healthy subjects, the exposure to tezosentan is 3.1- and 8.5-fold greater in cohorts II and III, respectively. Patients are more sensitive than healthy subjects to the pharmacodynamic effects of tezosentan, as reflected in increases in endothelin-1 concentrations. Tezosentan is well tolerated. Decreases in blood pressure are similar in patients treated with tezosentan or placebo. Moderate/severe liver impairment is associated with increased exposure to tezosentan, which is more pronounced in patients with elevated bilirubin levels, necessitating dose reduction.

The platelet and platelet function testing in liver disease

Patients who have liver disease commonly present with alterations in platelet number and function. Recent data have questioned the contribution of these changes to bleeding complications in these patients. Modern tests of platelet function revealed compensatory mechanisms for the decreased platelet number and function, the most prominent compensatory mechanism being substantially elevated levels of the adhesive protein von Willebrand's factor. Consequently, standard diagnostic tests of platelet functions seem to be of little use to predict bleeding complication in patients who have liver disease. This article outlines the role of platelet abnormalities and possibilities for platelet function testing in patients who have liver disease.

Bedside sublingual video imaging of microcirculation in assessing bacterial infection in cirrhosis

Bacterial infections are common in cirrhosis and can lead to life-threatening complications. Sidestream dark-field (SDF) imaging has recently emerged as a noninvasive tool for capturing real-time video images of sublingual microcirculation in critically ill patients with sepsis. The objective of this study was to assess the utility of SDF in determining underlying infection in patients with cirrhosis. Sublingual microcirculation was compared among patients with compensated cirrhosis (Group A, n=13), cirrhosis without sepsis (Group B, n=18), cirrhosis with sepsis (Group C, n=14), and sepsis only (Group D, n=10). The blood flow was semi-quantitatively evaluated in four equal quadrants in small (10-25 mm); medium (26-50 mm); and large (51-100 mm) sublingual capillaries. The blood flow was described as no flow (0), intermittent flow (1), sluggish flow (2), and continuous flow (3). The overall flow score or microvascular flow index (MFI) was measured for quantitative assessment of microcirculation and predicting power for concurrent infection in cirrhosis. Marked impairment was observed at all levels of microvasculature in Groups B and C when compared with Group A. This effect was restricted to small vessels only when Group B was compared with Group C. MFI<1.5 was found to have highest sensitivity (100%) and specificity (100%) for infection in decompensated cirrhosis. SDF imaging of sublingual microcirculation can be a useful bedside diagnostic tool to assess bacterial infection in cirrhosis.

Paraumbilical collateral veins on MRI as possible protection against portal venous thrombosis in candidates for liver transplantation

BACKGROUND

We retrospectively evaluate the potential protective influence of patent paraumblical vein (PUV) collaterals against portal vein (PV) thrombosis and reduced PV diameter in candidates for orthotopic liver transplant (OLT) METHODS: Dynamic 3D contrast-enhanced MRI at 1.5T was obtained in 309 patients with cirrhosis without evidence of malignancy. All MR studies were reviewed by one reader for PUV collaterals, PV thrombosis and PV diameter. Statistical analysis was performed by Fisher exact tests; 50 selected studies were reviewed independently by two additional readers to determine interobserver agreement via intraclass correlation coefficient (ICC).

RESULTS

Patent PUV was noted in 119 of 309 patients (38.5%). Mean PV diameter was 13.4 +/- 3.0 mm in patients with PUV compared with 11.3 +/- 3.6 mm without PUV (P < 0.01). Main PV thrombosis was present in 13 of 309 patients (4.2%) and significantly more frequent in those without PUV than with PUV (6.3% vs. 0.8%, P < 0.05). ICC indicated almost perfect agreement among three readers for presence of PUV collaterals (ICC = 0.91) and PV thrombosis (ICC = 0.96).

CONCLUSION

Our results suggest that patients with patent PUV appear less likely to develop main PV thrombosis or small PV diameter, suggesting a protective effect of PUV on PV patency.

Platelets in liver transplantation: friend or foe?

Apart from the well-known role of blood platelets in hemostasis, there is emerging evidence that platelets have various nonhemostatic properties that play a critical role in inflammation, angiogenesis, tissue repair and regeneration, and ischemia/reperfusion (I/R) injury. All these processes may be involved in the (patho)physiological alterations occurring in patients undergoing liver transplantation. Experimental and clinical research points toward a dualistic role of platelets in patients undergoing liver transplantation, resulting in both beneficial and detrimental effects. Although a low platelet count is generally considered a risk factor for perioperative bleeding, recent studies have indicated that platelet function in patients with cirrhosis may not be as abnormal as previously assumed. Platelet transfusions are frequently considered in liver transplant recipients to correct low platelet counts and to prevent bleeding; however, evidence-based transfusion thresholds are lacking, and the other detrimental and nonhemostatic properties of platelets are generally not weighed in this respect. First, platelets have been shown to contribute to I/R injury of the liver graft via induction of sinusoidal endothelial cell apoptosis. Second, platelet transfusion has been identified as an independent risk factor for reduced survival via mechanisms that are not completely understood yet. On the other hand, recent studies indicate that platelets are critically involved in restoration after liver injury and in liver regeneration via serotonin-mediated mechanisms. These findings make platelets both friend and foe in liver transplantation. The scientific challenge will be to further dissect the mechanisms and clinical relevance of these contrasting roles of platelets in liver transplantation.

Hemodynamic changes in splanchnic blood vessels in portal hypertension

Portal hypertension (PHT) is associated with a hyperdynamic state characterized by a high cardiac output, increased total blood volume, and a decreased splanchnic vascular resistance. This splanchnic vasodilation is a result of an important increase in local and systemic vasodilators (nitric oxide, carbon monoxide, prostacyclin, endocannabinoids, and so on), the presence of a splanchnic vascular hyporesponsiveness toward vasoconstrictors, and the development of mesenteric angiogenesis. All these mechanisms will be discussed in this review. To decompress the portal circulation in PHT, portosystemic collaterals will develop. The presence of these portosystemic shunts are responsible for major complications of PHT, namely bleeding from gastrointestinal varices, encephalopathy, and sepsis. Until recently, it was accepted that the formation of collaterals was due to opening of preexisting vascular channels, however, recent data suggest also the role of vascular remodeling and angiogenesis. These points are also discussed in detail.

Endothelial nitric oxide synthase is a critical factor in experimental liver fibrosis

Reduced expression of endothelial nitric oxide synthase (eNOS) in chronic liver disease can reduce hepatic perfusion and accelerate fibrosis. The relationship between eNOS expression and liver fibrogenesis remains unclear. We investigated whether L-arginine attenuated chronic liver fibrosis through eNOS expression. Chronic liver injury was induced by administration of carbon tetrachloride (CCl(4)) to mice for 8 weeks. 5-Methylisothiourea hemisulphate (SMT), an iNOS inhibitor, or L-arginine, a NOS substrate were injected subcutaneously. CCl(4)-induced hepatotoxicity, oxidative stress and accumulation of collagen were detected in the liver. The expression levels of inducible NOS (iNOS) and nuclear factor kappa-B (NF-kappaB) activity in the liver after CCl(4) treatment were increased but eNOS expression and activator protein-1 (AP-1) activity were decreased. Both SMT and L-arginine effectively reduced CCl(4) induced oxidative stress and collagen formation, but L-arginine showed a significantly greater suppression of collagen formation, iNOS expression and NF-kappaB activity. L-arginine also restored the level of eNOS and AP-1 activity. L-arginine was more effective than SMT in suppressing liver fibrosis. L-arginine might improve NO production which facilitates hepatic blood flow and thus retards liver fibrogenesis. Our results showed that the reduced eNOS expression in CCl(4)-treated mice was reversed by L-arginine. Furthermore, L-arginine also reversed the reduced AP-1 activity, an eNOS promoter.

Urotensin II in chronic liver disease: in vivo effect on vascular tone

OBJECTIVE

Urotensin II (UII) is now recognized as the most potent human vasoconstrictor. Although its role in human pathophysiology is unknown, vasoactive mediators are known to be important in the pathogenesis of portal hypertension complicating chronic liver disease. The objective of this study was to investigate the role of UII in liver cirrhosis via examination of the in vivo effect of UII in this patient group.

MATERIAL AND METHODS

The vasoactive effects of UII were measured using Laser Doppler velocimetry on cirrhotic patients (n = 14) and age-matched healthy controls (n = 14) after UII administration by iontophoresis to the cutaneous microcirculation of the forearm.

RESULTS

In vivo administration of UII produced vasoconstriction of the cutaneous microcirculation in the cirrhotic group and vasodilatation in the controls, with values differing significantly at the two highest doses of UII: 10(-9) mol (p = 0.01) and 10(-7) mol (p = 0.004).

CONCLUSIONS

UII mediates vasoconstriction of the microcirculation of cirrhotics but not of controls. This suggests that UII has pathophysiological relevance in the portal hypertensive population through its vasoactive properties. Further studies of UII and UII-antagonists are warranted in this patient population.

Urotensin II: a novel vasoactive mediator linked to chronic liver disease and portal hypertension

BACKGROUND/AIMS

Urotensin II (UII) is recognised as the most potent human vasoconstrictor; however, its role in chronic liver disease (CLD) is unknown.

AIM

We sought to determine serum UII levels in CLD and explore its relationship with clinical features and outcomes of patients with CLD and portal hypertension.

METHODS

UII was analysed by radio-immunoassay on cirrhotic patients undergoing hepatic venous pressure gradient (HVPG) determination and age- and sex-matched controls. Follow-up data were prospectively recorded.

RESULTS

From 1997 to 2004, 80 patients (male/female: 74/6) underwent a total of 94 HVPG assessments. UII was higher in cirrhotic patients compared with controls (2.05+/-0.06 and 1.55+/-0.09 pmol/L, P<0.001) and was correlated with HVPG (r=+0.35, P=0.001) and severity of CLD (r=+0.6, P<0.001). UII was higher in patients who developed refractory ascites (2.45+/-0.13 vs. 1.7+/-0.12 pmol/L, P<0.001) and in those who died during the follow-up period (2.27+/-0.15 pmol/L vs. 1.95+/-0.08 pmol/L, P<0.05).

CONCLUSION

Serum UII is elevated in patients with CLD, and is associated with the severity of the underlying liver disease and the degree of portal hypertension. Baseline levels can predict future complications such as refractory ascites and patient survival.

Modifications produced by indomethacin and L-NAME in the effect of ultralow-dose aspirin on platelet activity in portal hypertension

In our previous study, we demonstrated the effect of ultralow-dose aspirin (ULDA) on platelet activity and bleeding in rats with portal hypertension (PHT) produced by portal vein ligation (PVL). This paper reports modifications in this effect caused by blocking NO production by nitro arginine methyl ester (NAME) and cyclooxygenase (COX) activity with indomethacin. PVL rats and sham-operated controls were treated with placebo, indomethacin or NAME and 30 min thereafter with placebo or ULDA treatment. Platelet activity was studied by a model of in vivo laser-induced thrombus production in the mesenteric circulation, induced hemorrhage time (IHT) and platelet aggregation ex vivo induced by adenosine diphosphate in an aggregometer. The PVL group receiving placebo showed a decreased platelet activity with prolonged IHT, an effect that was reversed by ULDA. Indomethacin induced a decreased platelet activity in the control rats and a prolonged IHT. In PHT with ULDA, in vivo platelet activity was enhanced but the normalization of IHT observed in rats without indomethacin was blunted. The addition of NAME normalized the diminished in vivo platelet aggregation and increased the IHT observed in PVL animals. These changes decreased the effect of ULDA in both sham-operated and PVL animals. The effect of indomethacin was more clearly modified by ULDA than the effect of NAME, thus suggesting that modifications in the COX pathway might alter the effect of ULDA. The simultaneous administration of indomethacin and ULDA could inhibit its beneficial effect on bleeding in rats with PHT.

Effect of carvedilol on portal hypertension depends on the degree of endothelial activation and inflammatory changes

OBJECTIVE

Bleeding from esophageal varices is a major complication of liver cirrhosis. Non-selective beta-blockers exert an influence on the functional part of portal hypertension, thereby reducing the risk of bleeding. Direct measurement of this functional part is not possible; nevertheless, pro-inflammatory markers as well as parameters of endothelial dysfunction might serve as surrogate markers. The aim of study was to assess the correlation between the therapeutic efficacy of carvedilol and markers of endothelial dysfunction and systemic inflammation in patients with liver cirrhosis and portal hypertension.

MATERIAL AND METHODS

Thirty-six patients with cirrhosis and portal hypertension were given carvedilol, 25 mg q.i.d. for 30 days. Hepatic venous pressure gradient (HVPG) and biochemical determinations were performed prior to and after the treatment. Eight healthy individuals served as controls for comparison of biochemical markers.

RESULTS

In the whole group of cirrhotic patients, HVPG decreased from 17.7+/-3.8 to 14.9+/-4.8 mmHg (p<0.001). Complete response was seen in 15 patients (42%). Baseline serum levels of E-selectin were significantly higher in responders than in non-responders (119.8+/-70.6 versus 52.6+/-25.7 ng/ml; p=0.023) and in controls (28.8+/-22.2 ng/ml; p=0.004). Furthermore, baseline TNF-alpha levels were significantly higher in responders than in non-responders (22.8+/-15.7 versus 7+/-8.9; p=0.047) and in controls (5.5+/-5.9 pg/ml; p=0.005). Serum levels of ICAM-1 showed the same trend (4360+/-2870 versus 2861+/-1577 versus 651+/-196 ng/ml), although differences did not reach statistical significance.

CONCLUSIONS

Markers of systemic inflammation and endothelial dysfunction seem to predict the hypotensive effect of carvedilol on portal hypertension in patients with liver cirrhosis and may be useful in the assessment of the efficacy of the therapy.

Coagulation disorders and hemostasis in liver disease: pathophysiology and critical assessment of current management

Normal coagulation has classically been conceptualized as a Y-shaped pathway, with distinct "intrinsic" and "extrinsic" components initiated by factor XII or factor VIIa/tissue factor, respectively, and converging in a "common" pathway at the level of the FXa/FVa (prothrombinase) complex. Until recently, the lack of an established alternative concept of hemostasis has meant that most physicians view the "cascade" as a model of physiology. This view has been reinforced by the fact that screening coagulation tests (APTT, prothrombin time--INR) are often used as though they are generally predictive of clinical bleeding. The shortcomings of this older model of normal coagulation are nowhere more apparent than in its clinical application to the complex coagulation disorders of acute and chronic liver disease. In this condition, the clotting cascade is heavily influenced by numerous currents and counter-currents resulting in a mixture of pro- and anticoagulant forces that are themselves further subject to change with altered physiological stress such as super-imposed infection or renal failure. This report represents a summary of a recent multidisciplinary symposium held in Charlottesville, VA. We present an overview of the coagulation system in liver disease with emphasis on the limitations of the current clinical paradigm and the need for a critical re-evaluation of the current tenets governing clinical practice. With the realization that there is often limited or conflicting data, we have attempted to represent diverse opinion and experience from the perspectives of both hepatology and hematology beginning with a brief update on the physiology of normal coagulation.

Portal hypertension produces an evolutive hepato-intestinal pro- and anti-inflammatory response in the rat

An inflammatory etiopathogeny can be suggested in portal hypertensive enteropathy since infiltration of the intestinal wall by mononuclear cells has been described in this condition. This work was carried out with the intention of shedding light on this matter. Male Wistar rats were divided into 4 control groups and 4 groups with partial portal vein ligation at 1, 2, 3 and 15 months. TNF-alpha, IL-1beta and IL-10 were quantified in liver and ileum by ELISA. CO and NO were measured in splanchnic and systemic vein by spectrophotometry and Griess reaction, respectively. Expression of constitutive and inducible isoforms of NO and HO were assayed by Western blot in liver and ileum. An increased hepatic release of proinflammatory mediators (TNF-alpha, IL-1beta and NO) associated with intestinal release of anti-inflammatory mediators (IL-10, CO) occurs in an early evolutive phase (1 month) of experimental portal hypertension. On the contrary, in the long-term (15 months), the increase in the intestinal release of proinflammatory mediators (TNF-alpha, IL-1beta) is associated with an increase in the hepatic release of anti-inflammatory mediators (IL-10, CO). These results suggest that experimental prehepatic portal hypertension presents changes in the serum and tissular (liver and small bowel) concentrations of mediators which are considered as pro- and anti-inflammatory.

Plasma nitrate/nitrite and endothelin-1 in patients with liver cirrhosis

The aims of this study were to examine the plasma nitrate/nitrite (NOx; two end products of nitric oxide metabolism) and endothelin-1 (ET-1) concentrations in patients with liver cirrhosis, and to investigate whether there is a relationship between these two vasoactive parameters and the course of disease. Twenty-eight patients with liver cirrhosis (11 HBV-related, four HCV-related, four alcohol-related, and nine with idiopathic etiology) and 25 healthy subjects (controls) were included in the study. The venous plasma concentrations of NOx and ET-1 were significantly higher (P<0.01 and P<0.001) in the patients with cirrhosis than in the controls. A significant increase in ET-1 was observed in the Child B subgroup vs. Child A (P<0.05), and in the Child C subgroup vs. either subgroup A or B (P<0.05). There were no statistical differences between study subgroups (Child A-C) in the mean of NOx values. Plasma NOx and ET-1 were significantly increased in patients with ascites compared to those without ascites (P<0.05 and P<0.01). Increased nitric oxide synthesis may be a compensation mechanism against endothelial injury. The highest ET-1 levels in Child C and moderately increased ET-1 levels in Child B, and the lower increase of ET-1 levels in Child A patients suggest that plasma ET-1 increases with the progression of the disease. The fact that NOx and ET-1 levels were higher in patients with decompensated cirrhosis (patients with ascites) than in those with compensated cirrhosis (patients without ascites), and the presence of a strong correlation between ET-1, NOx, and the degree of varices, supports the suggestion that there is a relationship between NOx, ET-1, and portal hypertension. Our study demonstrates that increased ET and nitric oxide metabolism is associated with the hemodynamic alterations induced by portal hypertension.

Research progress of vasculopathy in portal hypertension

Portal hypertension, one of the vascular diseases, not only has lesions in liver, but also changes in vascular structures and functions of extrahepatic portal system, systemic system and pulmonary circulation. The pathological changes of vasculopathy in portal hypertension include remodeling of arterialized visceral veins, intimal injury of visceral veins and destruction of contractile structure in visceral arterial wall. The mechanisms of vasculopathy in portal hypertension may be attributed to the changes of hemodynamics in portal system, immune response, gene modulation, vasoactive substances, and intrahepatic blood flow resistance. Portal hypertension can cause visceral hyperdynamic circulation, and the development and progression of visceral vasculopathy, while visceral vasculopathy can promote the development and progression of portal hypertension and visceral hyperdynamic circulation in turn. The aforementioned three factors interact in the pathogenesis of hepatic cirrhosis-induced portal hypertension and are involved in hemorrhage due to varicose vein rupture.