Hepatitis B virus inhibits liver regeneration via epigenetic regulation of urokinase-type plasminogen activator

Liver regeneration after liver damage caused by toxins and pathogens is critical for liver homeostasis. Retardation of liver proliferation was reported in hepatitis B virus (HBV) X protein (HBx)-transgenic mice. However, the underlying mechanism of the HBx-mediated disturbance of liver regeneration is unknown. We investigated the molecular mechanism of the inhibition of liver regeneration using liver cell lines and a mouse model. The mouse model of acute HBV infection was established by hydrodynamic injection of viral DNA. Liver regeneration after partial hepatectomy was significantly inhibited in the HBV DNA-treated mice. Mechanism studies have revealed that the expression of urokinase-type plasminogen activator (uPA), which regulates the activation of hepatocyte growth factor (HGF), was significantly decreased in the liver tissues of HBV or HBx-expressing mice. The down-regulation of uPA was further confirmed using liver cell lines transiently or stably transfected with HBx and the HBV genome. HBx suppressed uPA expression through the epigenetic regulation of the uPA promoter in mouse liver tissues and human liver cell lines. Expression of HBx strongly induced hypermethylation of the uPA promoter by recruiting DNA methyltransferase (DNMT) 3A2.

CONCLUSION

Taken together, these results suggest that infection of HBV impairs liver regeneration through the epigenetic dysregulation of liver regeneration signals by HBx.

The impact of inosine triphosphatase variants on hemoglobin level and sustained virologic response of chronic hepatitis C in Korean

TWO VARIANTS OF THE INOSINE TRIPHOSPHATASE (ITPA

rs1127354, rs7270101) gene cause ITPA deficiency and protect against the hemolytic toxicity of ribavirin. We investigated the clinical significance of ITPA variants in Korean patients treated with pegylated interferon (PEG-IFN) plus ribavirin. Of the 133 patients, 108 were CC and 25 were non-CC at rs1127354 (groups A and B, respectively). On the other hand, at rs7270101 all 133 were AA. The mean values of Hemoglobin (Hgb) after 4, 8, and 12 weeks of treatment in groups A and B were 12.2 and 14.0, 11.8 and 13.2, and 11.5 and 12.9, respectively (P=0.001, 0.036, 0.036). Sustained virologic response (SVR) was achieved in 67.8% (40/59) of genotype 1 patients and in 75% (27/36) of non-genotype 1 patients. Regarding ITPA variants, SVR was achieved by 66% and 80% of genotype 1 (P=0.282), and by 78% and 71% (P=0.726) of non-genotype 1. SVR was not significantly different in groups A and B. In conclusion, non-CC at rs1127354 without involvement of rs7270101 is strongly associated with protection from ribavirin-induced anemia, however, ITPA genotype is not associated with SVR.

Liver disease and malnutrition

Patients with hepatic disorders are exceptionally vulnerable to developing malnutrition because of the key role played by the liver in regulating the nutritional state and the energy balance. Moreover, the presence of chronic liver disorders could reduce the appetite and thus influence the nutrient intake. Poor nutritional status has been shown in various patient groups with hepatic disorders, and particularly in patients with alcoholic cirrhosis who are at high nutritional risk. It is well established that malnourished patients with liver diseases generally have a higher risk of developing adverse clinical outcomes and increased healthcare costs. Nutrition screening with the Subjective Global Assessment and anthropometric measurements are an important first step in the early identification of malnutrition and initiates the whole nutrition care process. It is therefore important for appropriate nutrition policies and protocols to be implemented so that all patients with chronic liver diseases are monitored closely from a nutritional standpoint. Early and evidence-based nutritional interventions are eagerly needed to minimize the nutritional decline associated with chronic liver disorders and ultimately improve the prognosis of such patients. This review includes a comprehensive analysis of methods to identify malnutrition in patients with chronic liver diseases as well as the extent and impact of the malnutrition problem in selected patient populations.

Incidence and risk factors for surveillance failure in patients with regular hepatocellular carcinoma surveillance

BACKGROUND

Initial presentation of hepatocellular carcinoma (HCC) at an advanced stage in patients under a regular surveillance program is a devastating problem.

AIMS

We assessed the prevalence and factors associated with this surveillance failure.

METHODS

A total of 304 HCC patients who received regular surveillance were retrospectively reviewed. Surveillance failure was defined when the tumor was diagnosed at beyond the Milan criteria.

RESULTS

Surveillance failure rate was 5.9 %. Macronodular cirrhosis (MC), ultrasonography-only surveillance (US-S) and infiltrative tumor type were independent factors associated with surveillance failure. The surveillance failure rate was higher in patients with MC (10.3 vs. 3.2 %, p = 0.022), US-S (14.6 vs. 4.3 %, p = 0.013) and when the tumor was infiltrative type (57.1 vs. 2.1 %, p < 0.001). Based on the two baseline factors (MC and US-S), the surveillance failure rates were 35.7, 6.8, 5.9 and 2.6 % for MC(+)/US-S(+), MC(+)/US-S(-), MC(-)/US-S(+) and MC(-)/US-S(-), respectively (p < 0.001).

CONCLUSION

The HCC surveillance failure was not rare in clinical practice. These data suggest that special attention for surveillance failure might be needed for patients with MC who receive US-S.

Targeting the gut-liver axis in cirrhosis: antibiotics and non-selective β-blockers

The gut-liver axis in cirrhosis and portal hypertension is gaining increasing attention as a key pathophysiological mechanism responsible for progression of liver failure and development of complications such as spontaneous infections and hepatocellular carcinoma. Antibiotics and non-selective β-blockers (NSBB) intercept this axis and each drug has proven efficacy in clinical trials. A synergistic effect is a hitherto unproven possibility. There is an increasing body of evidence supporting improved outcome with expanded use of NSBB and antibiotic therapy beyond current indications. This review addresses the issue of pharmacological treatment of cirrhosis and portal hypertension with antibiotics and NSBB. We discuss their mechanism of action and suggest that combining the two treatment modalities could potentially reduce the risk of complications.

Egy-score predicts severe hepatic fibrosis and cirrhosis in Egyptians with chronic liver diseases: a pilot study

BACKGROUND

Non-invasive methods for assessment of hepatic fibrosis are increasingly needed. Recent studies showed that combined elevation of tumor markers CA 19-9 and CA 125 is predictive of severe hepatic fibrosis or cirrhosis with high specificity.

OBJECTIVES

We aimed at developing a new panel of surrogate biomarkers for prediction of the stage of hepatic fibrosis by combining tumor markers with other known biomarkers of hepatic fibrosis.

PATIENTS AND METHODS

A total of 92 patients with different types of chronic liver diseases (chronic hepatitis B, chronic hepatitis C and autoimmune hepatitis), were prospectively enrolled in our cohort. They were subjected to: ALT, AST, GGT, ALP, total bilirubin, INR, total cholesterol, albumin, platelet count, cancer antigen 19-9 (CA 19-9), cancer antigen 125 (CA 125), cancer antigen 15-3 (CA 15-3), haptoglobin, alpha-2-macroglobulin, apolipoprotein A1, abdominal ultrasound, liver biopsy and histological staging of hepatic fibrosis using the METAVIR system.

RESULTS

Combined elevation of CA 19-9 and CA 125 with a summated value > 37 U/mL is predictive of severe hepatic fibrosis or cirrhosis (stage F3-F4 METAVIR) with a probability of 77.6%. Multivariate analysis showed that the most relevant collection of biomarkers for prediction of stage of hepatic fibrosis is: CA 19-9, age, alpha-2- macroglobulin, total bilirubin, platelet count & albumin. We developed a new score, named the "Egy-Score", using a regression equation composed of this panel of biomarkers. Egy-Score could differentiate no or early fibrosis (stage F0-F2 METAVIR) from severe fibrosis or cirrhosis (stage F3-F4 METAVIR) with 83.7% accuracy.

CONCLUSIONS

Non-invasive assessment of hepatic fibrosis could be done using the Egy-Score. Egy-Score could differentiate no or early fibrosis (stage F0-F2 METAVIR) from severe fibrosis or cirrhosis (stage F3 - F4 METAVIR) with 83.7% accuracy.

Hepatocellular carcinoma in patients with chronic hepatitis C virus infection in the Asia-Pacific region

Hepatocellular carcinoma (HCC) is the third-leading cause of cancer-related mortality worldwide. Although hepatitis B still remains the most common risk factor worldwide, chronic hepatitis C virus (HCV) infection is the driving force for the increased incidence of HCC especially in Western countries and Japan. In hepatitis B virus (HBV)-endemic areas, after successful vaccination programs against HBV, chronic HCV infection is now emerging as an important cause of chronic liver diseases. Unlike patients with chronic hepatitis B, those with chronic hepatitis C (CHC) develop HCC in the presence of established cirrhosis in most cases. However, a significant minority of CHC develops HCC in the absence of cirrhosis. Although HCV is a RNA virus with little potential for integrating its genetic material into host genome, various HCV proteins, including core, envelope, and nonstructural proteins, have oncogenic properties by inducing oxidative stress, disturbing cellular regulatory pathways associated with proliferation and apoptosis, and suppressing host immune responses. Overall, a combination of virus-specific, host genetic, environmental, and immune-related factors are likely to determine progression to HCC. Strategies aimed at eliminating the virus may provide opportunities for effective prevention of the development of HCC. Pegylated interferon plus ribavirin therapy appears to be effective at reducing the risk of HCC in patients who achieve sustained virologic responses. In summary, with the emerging importance of CHC, mechanisms of HCV-associated hepatocellular carcinogenesis should be clarified to provide insight into advanced therapeutic and preventive approaches, which eventually decrease the incidence and mortality of HCC.

Differential regulation of host genes including hepatic fatty acid synthase in HBV-transgenic mice

Hepatitis B virus (HBV) is the most common of the hepatitis viruses that cause chronic liver infections in humans, and it is considered to be a major global health problem. To gain a better understanding of HBV pathogenesis, and identify novel putative targets for anti-HBV therapy, this study was designed to elucidate the differential expression of host proteins in liver tissue from HBV-transgenic mice. Liver samples from two groups, (1) HBV-transgenic (Tg) mice, (2) corresponding background normal mice, wild-type (WT) mice, were collected and subjected to iTRAQ and mass spectrometry analysis. In total, 1950 unique proteins were identified, and 68 proteins were found to be differentially expressed in HBV-Tg mice as compared with that in WT mice. Several differentially expressed proteins were further validated by real-time quantitative RT-PCR, Western blot and immunohistochemical analysis. Furthermore, the association of HBV replication with fatty acid synthase (FASN), one of the highly expressed proteins in HBV-Tg mice, was verified. Silencing of FASN expression in HepG2.2.15 cells suppressed viral replication through the IFN signaling pathway, and some downstream antiviral effectors. The implicated role of FASN in HBV replication provides an opportunity to test existing compounds against FASN for adjuvant therapy and/or treatment of HBV replication.

Relationship between vascular endothelial growth factors and liver diseases

Vascular endothelial growth factors play an important role in the processes of cell differentiation and maturation. As a kind of multi-functional factor, they are closely related to the occurrence and progression of liver diseases. They can not only promote postoperative liver regeneration but also repress the propagation of chronic hepatitis B and liver cirrhosis. In addition, they have a role in cancer diagnosis and treatment and graft rejection in liver transplantation. In this paper, we will give a brief introduction of vascular growth factors and their role in liver regeneration, cirrhosis, liver cancer and liver transplantation.

Factors affecting re-bleeding after injection of cyanoacrylate for gastric varices

AIM: To investigate the rate of re-bleeding after injection of cyanoacrylate for gastric varices in patients with large gastric varices and to identify probable risk factors for re-bleeding.

METHODS: A retrospective analysis was carried out in 52 cirrhotic patients who had large gastric varices and underwent endoscopic cyanoacrylate injection at our hospital from June 2010 to April 2012. To identify probable risk factors for re-bleeding after injection of cyanoacrylate for gastric varices, various factors were collected and analyzed, including gender, age, types of cirrhosis, coexistent hepatocellular carcinoma, Child-Pugh classification, presence of ascites, portal vein thrombosis, diameter of portal vein and spleen vein, spleen length, spleen thickness, routine blood tests, liver function tests, renal function tests, coagulation function tests, fasting blood sugar, α fetal protein, Child score, MELD score, and endoscopic variceal characteristics.

RESULTS: Recurrent bleeding occurred in 18 patients (34.62%) after initial cyanoacrylate injection, and the mean re-bleeding time was 5.5 mo ± 4.9 mo. Logistic regression analysis revealed that Child-Pugh classification, gamma-glutamyl transpeptidase (GGT) and spleen length were probable risk factors for recurrent bleeding after cyanoacrylate injection (P = 0.036, 0.009, 0.033; OR = 15.262, 47.684, 38.249; 95%CI: 1.197-194.573, 2.604-873.328, 1.339-1 092.543). The areas under ROC curve of GGT and spleen length in the diagnosis of re-bleeding were 0.773 and 0.704, with sensitivities of 66.7% and 93.8% and specificities of 85.7% and 52.6%.

CONCLUSION: Recurrent bleeding after injection of cyanoacrylate for gastric varices is affected by Child-Pugh B or C, GGT and spleen length.

Clinical application of liver stiffness measurement using transient elastography in chronic liver disease from longitudinal perspectives

Accurate determination of the presence and degree of fibrosis in liver is of great importance, because the prognosis and management strategies for chronic liver disease depend mainly on these factors. To date, liver biopsy (LB) remains the “gold standard” for assessing the severity of liver fibrosis; however, LB is often limited by its invasiveness, sampling error, and intra/inter-observer variability in histological interpretation. Furthermore, repeated LB examinations within a short time interval are indeed ineligible in a real clinical practice. Thus, due to the pressing need for non-invasive surrogates for liver fibrosis, transient elastography (TE), as a novel ultrasound based technology, has allowed a noninvasive measurement of liver stiffness and has gained in popularity over recent years. In the past few years, additional roles for transient TE beyond the initial purpose of a non-invasive surrogate for LB have included the prediction of the most two critical consequences of fibrosis progression: the development of portal hypertension-related complications and hepatocellular carcinoma. This indicates that the role of transient TE is not merely limited to reducing the need for LB, but transient TE can enable the establishment of tailored management strategies by providing more detailed prognostic information. In particular, under the concept in which the clinical course of liver fibrosis is dynamic and bidirectional, especially when appropriate intervention is commenced, transient TE can be used to track the dynamic changes in fibrotic burden during antiviral or antifibrotic treatment. This review discussed extended applications of transient TE in prediction of the development of real clinical endpoints from a longitudinal perspective.

A case of solitary necrotic nodule treated with laparoscopic hepatectomy: spontaneous regression of hepatocellular carcinoma?

Solitary necrotic nodule of the liver is a rare benign lesion with a completely necrotic core and a hyalinized fibrotic capsule containing elastic fibers. The pathogenetic mechanism is still unclear. We here describe a case of SNN, whose central reticulin fibers within the nodule suggest the origin as hepatocellular carcinoma or other hepatocyte-origin tumors, treated with laparoscopic anatomical segmentectomy of the liver. A 76-year-old Japanese female, with no prior medical history and no symptom, visited our hospital with the heterogeneous hypoechoic lesion in the liver segment VI incidentally pointed out in abdominal ultrasonography. Computed tomography with contrast demonstrated a 1.1 cm sized low-density lesion with mild ring enhancement on the rim in the arterial phase. Since the possibility of malignant tumor with necrotic change could not be ruled out, she underwent laparoscopic anatomical segmentectomy of the liver. In the histological examination of the surgical specimen, the liver nodule was necrotic tissue without viable cells and signs of inflammation, which had fibrous capsule and central cystic change and showed trabecular pattern alignment of ghost cells and reticulin fibers orthogonal to the capsule. Also, the findings of chronic hepatitis were observed in the background liver.

Analysis of hepatitis C virus subgenotypes in patients in Heilongjiang province

AIM: To analyze the distribution of different hepatitis C virus (HCV) subgenotypes in Heilongjiang province, China.

METHODS: Serum samples from 1 313 patients with HCV infection, including 627 (47.75%) males and 686 (52.25%) females, were subgenotyped using multiplex nested PCR assay. The associations of HCV subgenotypes with gender, age, viral load, and ALT level were analyzed.

RESULTS: Of 1 313 patients, 927 (70.60%) were successfully subgenotyped. Among typable subgenotypes, 1b⁺/2a^- was found in 388 (41.86%) cases, 2a⁺/1b^- in 318 (34.30%) cases, 1b+2a in 197 (21.25%) cases, and 1a+/2b in 24 (2.59%) cases. The percentage of patients with 2a⁺/1b^- subgenotype was significantly higher in females (37.50%) and patients with HCVRNA of (1.000-9.999) × 10⁴ (54.55%), ALT level >200 (60.87%) or ≤ 40 (41.02%) (all P < 0.05). The percentage of patients with 1b⁺/2a^- subgenotype was significantly lower in patients with HCVRNA of (1.000-9.999) × 10⁴ (24.24%) or ALT level >200 (13.04%) (both P < 0.05).

CONCLUSION: Genotypes 1b and 2a are the most prevalent genotypes in Heilongjiang province. The distribution of different HCV subgenotypes is associated with gender, viral load, and ALT level.

Systems biology of adipose tissue metabolism: regulation of growth, signaling and inflammation

Adipose tissue (AT) depots actively regulate whole body energy homeostasis by orchestrating complex communications with other physiological systems as well as within the tissue. Adipocytes readily respond to hormonal and nutritional inputs to store excess nutrients as intracellular lipids or mobilize the stored fat for utilization. Co-ordinated regulation of metabolic pathways balancing uptake, esterification, and hydrolysis of lipids is accomplished through positive and negative feedback interactions of regulatory hubs comprising several pleiotropic protein kinases and nuclear receptors. Metabolic regulation in adipocytes encompasses biogenesis and remodeling of uniquely large lipid droplets (LDs). The regulatory hubs also function as energy and nutrient sensors, and integrate metabolic regulation with intercellular signaling. Over-nutrition causes hypertrophic expansion of adipocytes, which, through incompletely understood mechanisms, initiates a cascade of metabolic and signaling events leading to tissue remodeling and immune cell recruitment. Macrophage activation and polarization toward a pro-inflammatory phenotype drives a self-reinforcing cycle of pro-inflammatory signals in the AT, establishing an inflammatory state. Sustained inflammation accelerates lipolysis and elevates free fatty acids in circulation, which robustly correlates with development of obesity-related diseases. The adipose regulatory network coupling metabolism, growth, and signaling of multiple cell types is exceedingly complex. While components of the regulatory network have been individually studied in exquisite detail, systems approaches have rarely been utilized to comprehensively assess the relative engagements of the components. Thus, need and opportunity exist to develop quantitative models of metabolic and signaling networks to achieve a more complete understanding of AT biology in both health and disease.

Human liver carboxylesterase 1 outperforms alpha-fetoprotein as biomarker to discriminate hepatocellular carcinoma from other liver diseases in Korean patients

Although alpha-fetoprotein (AFP) is currently the major serologic biomarker for hepatocellular carcinoma (HCC), it cannot efficiently distinguish this cancer from other forms of liver disease in early diagnosis due to its low sensitivity. The aim of this study is to compare sensitivity and specificity of human carboxylesterase 1 (hCE1) and AFP biomarker. Antibody-based assays for hCE1 and AFP were used to test both biomarkers with respect to diagnostic efficiency, Youden's index and the area under the curve (AUC) through receiver operating characteristic (ROC) analysis in plasma from 208 patients with HCC (n=57), liver cirrhosis (n=27), chronic hepatitis (n=37), cholangiocarcinoma (n=22), gastric cancer (n=31) and pancreatic cancer (n=34), along with 52 healthy donors (HDs). The levels of hCE1 were significantly higher in patients with HCC than HDs and the other diseases (p<0.005), further verified by AUC values and Youden's index. In the set of HCC versus liver cirrhosis the AUC values were 0.744 (AFP), 0.918 (hCE1) and 0.938 (combination of AFP and hCE1), respectively. These results indicate that hCE1 is not only a more potent and specific marker in distinguishing cancer from liver diseases, in particular cirrhosis, but the combination of hCE1 and AFP shows also synergistic potential for greater sensitivity and specificity in early diagnosis. Therefore the antibody-based hCE1 assay appears to have high diagnostic efficiency for discriminating HCC from other forms of liver disease. It is now feasible to further validate this novel plasma-based biomarker in the large cohort we assembled.

Anti-oxidant and natural killer cell activity of Korean red ginseng (Panax ginseng) and urushiol (Rhus vernicifera Stokes) on non-alcoholic fatty liver disease of rat

Anti-oxidative and immunologic effects of the Korea red ginseng (KRG; Panax ginseng) and urushiol (Rhus vernicifera Stokes) on non-alcoholic fatty liver disease (NAFLD) were evaluated. Forty-five rats (five Long-Evans Tokushima Otsuka and 40 Otsuka Long-Evans Tokushima Fatty [OLETF] rats) received chew diets for 10months; after this period. The OLETF rats were divided into the following four groups according to diet for 2months: NAFLD (chew), KRG (chew+KRG [200mg/kg/day]), urushiol (chew+urushiol [0.5mg/kg/day]), and ursodeoxycholic acid (UDCA) (chew+UDCA [15mg/kg/day]) groups. Liver function, lipid profiles and anti-oxidant activity of liver and serum, natural killer (NK) cell activity, and pathology were compared. In KRG and urushiol groups, the level of serum triglyceride ([302.0±70.4 and 275.2±63.8] vs. 527.7±153.3mg/dL) were lower compared with that of NAFLD group (p<0.05). The levels of HDL-cholesterol (liver tissue: [4.8±0.2 and 4.8±0.5] vs. 4.2±0.2mg/g) and NK cell activity ([3485±910 and 3559±910] vs. 2486±619 counts) were significantly higher than those of the NAFLD group (p<0.001). Inflammation with neutrophil infiltration was observed in only two rats in the NAFLD group. These results suggest that 2months of oral KRG or urushiol administration improves lipid profiles and stimulates NK cell activity, while inhibiting steatohepatitis in OLEFT rats.

Eicosanoids in metabolic syndrome

Chronic persistent inflammation plays a significant role in disease pathology of cancer, cardiovascular disease, and metabolic syndrome (MetS). MetS is a constellation of diseases that include obesity, diabetes, hypertension, dyslipidemia, hypertriglyceridemia, and hypercholesterolemia. Nonalcoholic fatty liver disease (NAFLD) is associated with many of the MetS diseases. These metabolic derangements trigger a persistent inflammatory cascade, which includes production of lipid autacoids (eicosanoids) that recruit immune cells to the site of injury and subsequent expression of cytokines and chemokines that amplify the inflammatory response. In acute inflammation, the transcellular synthesis of antiinflammatory eicosanoids resolve inflammation, while persistent activation of the autacoid-cytokine-chemokine cascade in metabolic disease leads to chronic inflammation and accompanying tissue pathology. Many drugs targeting the eicosanoid pathways have been shown to be effective in the treatment of MetS, suggesting a common linkage between inflammation, MetS and drug metabolism. The cross-talk between inflammation and MetS seems apparent because of the growing evidence linking immune cell activation and metabolic disorders such as insulin resistance, dyslipidemia, and hypertriglyceridemia. Thus modulation of lipid metabolism through either dietary adjustment or selective drugs may become a new paradigm in the treatment of metabolic disorders. This review focuses on the mechanisms linking eicosanoid metabolism to persistent inflammation and altered lipid and carbohydrate metabolism in MetS.

Biomarkers: evaluation of screening for and early diagnosis of hepatocellular carcinoma in Japan and china

Over the past few decades, the screening for and early diagnosis of hepatocellular carcinoma (HCC) has attracted attention worldwide, and especially in Asian countries such as Japan and China. Such approaches can help detecting HCC at an earlier stage when curable interventions can be offered to achieve long-term disease-free survival for patients. Biomarkers have been used to screen for and diagnose HCC in various countries. In Japan, the combined tests of des-Γ-carboxyprothrombin (DCP) and α-fetoprotein (AFP) or Lens culinaris agglutinin-reactive fraction of AFP (AFP-L3) have been shown to achieve a high level of sensitivity and specificity. These tests have routinely been used to screen for HCC and are covered by Japan's national health insurance. Due to the routine practice of screening for HCC among high-risk patients, HCC nodules have been detected in the early stages in more than 60% of patients in Japan. In contrast, although several remarkable advances in the management of HCC have been made in China over the past few decades, most HCC patients still present with advanced-stage disease. AFP is the only serum biomarker that has widely been used to screen for and diagnose HCC in China. In recent years, several molecular biological studies have further investigated the clinical usefulness of DCP, and they have found that it may facilitate the screening for and diagnosis of HCC and assist with the assessment of HCC progression. DCP can serve as a biomarker to detect HCC in an early stage and facilitate definitive treatment. The wide implementation of DCP is expected, especially in China where 55% of HCC cases worldwide live.

Evolution of portal hypertension and mechanisms involved in its maintenance in a rat model

In rats with portal hypertension induced by partial ligation of the portal vein, we have recently demonstrated an increased portal venous inflow that becomes an important factor in the maintenance of portal hypertension. The sequence of events that leads into this circulatory disarray is unknown. We evaluated chronologically the chain of hemodynamic changes that occurred after portal hypertension was induced by partial ligation of the portal vein. In this model it is possible to follow, from the initiation of the portal-hypertensive state, the interaction between blood flow and resistance in the portal system as well as the relation between the development of portal-systemic shunting and the elevated portal venous inflow. The study was performed in 45 portal-hypertensive rats and in 29 sham-operated rats. Blood flow and portal-systemic shunting were measured by radioactive microsphere techniques. The constriction of the portal vein was immediately followed by a resistance-induced portal hypertension characterized by increased portal resistance (9.78 +/- 0.89 vs. 4.18 +/- 0.71 dyn X s X cm-5 X 10(4), mean +/- SE, P less than 0.01), increased portal pressure (17.7 +/- 0.9 vs. 9.5 +/- 0.6 mmHg, P less than 0.001), and decreased portal venous inflow (3.93 +/- 0.26 vs. 6.82 +/- 0.49 ml X min-1 X 100 g body wt-1, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)