Mutations of hepatitis B virus liver disease

Individuals with chronic hepatitis B virus (HBV) infection are generally divided into asymptomatic healthy carriers and patients with chronic liver disease. Several studies have suggested that the core antigen (HBcAg) could be an immunological target of cytotoxic T lymphocytes (CTL). To investigate the possible pressure site from CTL, the entire core region of HBV DNA was sequenced in 30 subjects (10 asymptomatic healthy carriers and 20 patients with chronic liver disease). No significant changes in the nucleotide sequence and deduced amino acid residue were noted in the 10 healthy carriers. In contrast, a cluster of changes in small segment of 18 amino acids (codon 84 to 101 from the start of the core gene) was found in 15 of the 20 chronic liver disease patients. All these 15 patients had advanced liver diseases (chronic active hepatitis and cirrhosis), whereas only mild liver disease (chronic persistent hepatitis) was found in the 5 patients without mutation. These data suggest that this region with clustering mutations may play an important role in the pathogenesis of B viral liver disease, and the mutations in the region may be related to progressive liver disease.     

Involvement of eicosanoids in the pathogenesis of pancreatic cancer: The roles of cyclooxygenase-2 and 5-lipoxygenase

The interplay between inflammation and cancer progression is a growing area of research. A combination of clinical, epidemiological, and basic science investigations indicate that there is a relationship between inflammatory changes in the pancreas and neoplastic progression. Diets high in ω-6 polyunsaturated fatty acids provide increased substrate for arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) to form eicosanoids. These eicosanoids directly contribute to pancreatic cancer cell proliferation. Both COX-2 and 5-LOX are upregulated in multiple cancer types, including pancreatic cancer. In vitro studies using pancreatic cancer cell lines have demonstrated upregulation of COX-2 and 5-LOX at both the mRNA and protein levels. When COX-2 and 5-LOX are blocked via a variety of mechanisms, cancer cell proliferation is abrogated both in vitro and in vivo. The mechanism of COX-2 has been shown to include effects on apoptosis as well as angiogenesis. 5-LOX has been implicated in apoptosis. The use of COX-2 and 5-LOX inhibitors in clinical studies in patients with pancreatic cancer has been limited. Patient enrollment has been restricted to those with advanced disease which makes evaluation of these drugs as chemopreventive agents difficult. COX-2 and 5-LOX expression have been shown to be present during the early neoplastic changes of pancreatic cancer, well before progression to invasive disease. This indicates that the ideal role for these interventions is early in the disease process as preventive agents, perhaps in patients with chronic pancreatitis or hereditary pancreatitis.     

Plasma Amino Acids in the Alcoholic: Nutritional Aspects

Plasma amino acid abnormalities are frequently reported in alcoholics, with the most common abnormalities being those of depressed branched chain amino acids (BCAA) and increased aromatic amino acids. The depression in branched chain amino acids is due to multiple factors including portal-systemic shunting, hyperinsulinemia, hyperglucagonemia (all due to advanced liver disease) as well as dietary deficiency. alpha-Amino-n-butyric acid is a nonessential amino acid derived primarily from the catabolism of methionine, threonine, and serine. Increased levels due to chronic alcohol consumption may reflect altered glutathione metabolism and lipid peroxidation due to alcohol and may be used empirically as a biochemical marker of heavy drinking. The high levels of aromatic amino acids such as tyrosine and tryptophan as well as their breakdown products may be due to impaired hepatic metabolism and appear to play a role in the pathogenesis of hepatic encephalopathy. The effects of high levels of aromatic amino acids may be potentiated by depressed BCAA; these normally compete with each other for CNS transport. Alterations in these amino acids may have implications for nutritional requirements for amino acids in these patients as well as therapeutic approaches.     

Sulfur Amino Acid Metabolism in Hepatobiliary Disorders

Sulfur amino acid metabolism was studied in patients with mild to severe forms of liver dysfunction and compared with that of healthy controls. Patients with mild liver dysfunction (for example, Gilbert's syndrome) had a normal sulfur amino acid metabolism. With increased inflammatory activity and cirrhosis (for example, chronic active hepatitis, alcohol-induced cirrhosis, and hepatic coma) a decreased ability to metabolize methionine (to cysteine, with cystathionine accumulation) and cysteine (to inorganic sulfate, with thiosulfate and N-acetylcysteine accumulation) was found. In contrast, transaminative metabolism of sulfur amino acids was preserved in patients with advanced forms of liver dysfunction, suggesting that transamination of sulfur amino acids is performed not only in the liver but also in extra-hepatic tissues. Some implications of these findings are discussed.     

Branched-chain amino acids in the treatment of chronic hepatic encephalopathy.

The therapeutic efficacy of orally administered branched-chain amino acids in patients with liver cirrhosis and chronic encephalopathy was examined in a double blind, randomised crossover study. Seven patients with manifest hepatic cirrhosis and encephalopathy of six months' duration or longer ingested 30 g branched-chain amino acids or placebo during two 14-day periods. Psychometric tests and electroencephalograms were used to evaluate cerebral function. Neither clinical observations nor psychometric testing or electroencephalogram indicated a significant difference in the patients' response to branched-chain amino acids as compared with placebo. In four patients given branched-chain amino acids for longer periods (five to 22 weeks), psychometric tests also remained unchanged. The plasma concentrations of these acids after oral intake increased significantly, demonstrating adequate absorption. Basal plasma amino acid concentrations were unchanged, however, after branched-chain amino acid therapy. No side-effects were seen, which indicates that these amino acids are well tolerated as an extra protein supply in patients with chronic hepatic encephalopathy. As compared with placebo, however, no effect of branched-chain amino acids on the encephalopathy could be detected.     

Mutations in SRD5B1 (AKR1D1), the gene encoding delta(4)-3-oxosteroid 5beta-reductase,in hepatitis and liver failure in infancy

BACKGROUND: A substantial group of patients with cholestatic liver disease in infancy excrete, as the major urinary bile acids, the glycine and taurine conjugates of 7alpha-hydroxy-3-oxo-4-cholenoic acid and 7alpha,12alpha-dihydroxy-3-oxo-4-cholenoic acid. It has been proposed that some (but not all) of these have mutations in the gene encoding delta(4)-3-oxosteroid 5beta-reductase (SRD5B1; AKR1D1, OMIM 604741). AIMS: Our aim was to identify mutations in the SRD5B1 gene in patients in whom chenodeoxycholic acid and cholic acid were absent or present at low concentrations in plasma and urine, as these seemed strong candidates for genetic 5beta-reductase deficiency. Patients and subjects: We studied three patients with neonatal onset cholestatic liver disease and normal gamma-glutamyl transpeptidase in whom 3-oxo-delta(4) bile acids were the major bile acids in urine and plasma and saturated bile acids were at low concentration or undetectable. Any base changes detected in SRD5B1 were sought in the parents and siblings and in 50 ethnically matched control subjects. METHODS: DNA was extracted from blood and the nine exons of SRD5B1 were amplified and sequenced. Restriction enzymes were used to screen the DNA of parents, siblings, and controls. RESULTS: Mutations in the SRD5B1 gene were identified in all three children. Patient MS was homozygous for a missense mutation (662 C>T) causing a Pro198Leu amino acid substitution; patient BH was homozygous for a single base deletion (511 delT) causing a frame shift and a premature stop codon in exon 5; and patient RM was homozygous for a missense mutation (385 C>T) causing a Leu106Phe amino acid substitution. All had liver biopsies showing a giant cell hepatitis; in two, prominent extramedullary haemopoiesis was noted. MS was cured by treatment with chenodeoxycholic acid and cholic acid; BH showed initial improvement but then deteriorated and required liver transplantation; RM had advanced liver disease when treatment was started and also progressed to liver failure. CONCLUSIONS: Analysis of blood samples for SRD5B1 mutations can be used to diagnose genetic 5beta-reductase deficiency and distinguish these patients from those who have another cause of 3-oxo-delta(4) bile aciduria, for example, severe liver damage. Patients with genetic 5beta-reductase deficiency may respond well to treatment with chenodeoxycholic acid and cholic acid if liver disease is not too advanced.     

Ductular proliferation in liver tissues with severe chronic hepatitis B： An immunohistochemical study

AIM: To clarify the pathogenesis of ductular proliferation and its possible association with oval cell activation and hepatocyte regeneration. METHODS: Immunohistochemical staining and image analysis of the ductular structures in the liver tissues from 11 patients with severe chronic hepatitis B and 2 healthy individuals were performed. The liver specimens were sectioned serially, and then cytokeratin 8 (CK8), CK19, OV6, proliferating cell nuclear antigens (PCNA), glutathione-S-transferase (GST),α-fetal protein (AFP) and albumin were stained immunohistochemically. RESULTS: Typical and atypical types of ductular proliferation were observed in the portal tracts of the liver tissues in all 11 patients. The proliferating ductular cells were positive for CK8, CK19, OV6 and PCNA staining. Some atypical ductular cells displayed the morphological and immunohistochemical characteristics of hepatic oval cells. Some small hepatocyte-like cells were between hepatic oval cells and mature hepatocytes morphometri-cally and immunohistochemically. CONCLUSION: The proliferating ductules in the liver of patients with severe chronic liver disease may have different origins. Some atypical ductular cells are actually activated hepatic oval cells. Atypical ductular proliferation is related to hepatocyte regeneration and small hepatocyte-like cells may be intermediate transient cells between hepatic oval cells and mature hepatocytes.     

Urinary excretion of methylarginine in human disease

Methylated amino acids are excreted in urine upon degradation of some tissue proteins. The urinary excretion ratios of N^G,N′^G-dimethylarginine (sym-DMA) and N^G,N^G-dimethylarginine (unsym-DMA) were studied in healthy adults and in patients with various diseases. The normal ratio of sym- to unsym-DMA in urine was 0.98 and ranged from 0.71 to 1.33; ratios were not significantly different in multiple sclerosis, cerebrovascular accident, cancer, and systemic lupus erythematosus. However, patients with liver disease, including chronic active hepatitis, were found on average to have a significantly altered ratio of 0.79, range 0.49–1.30, owing to an increase in the excretion of unsym-DMA. Hence measurements of the urinary excretion of dimethylarginine could become a useful aid in assessing recovery of liver cells in patients with chronic liver disease.     

Sleep disorders in chronic liver disease

Sleep-related complaints and disturbances are increasingly recognized in the setting of chronic liver disease and have recently been shown to be an important prognostic factor in patients with advanced chronic liver disease. This article reviews the literature surrounding sleep disturbances and disorders in a variety of types of chronic liver disease. This includes the association of sleep disturbances with hepatitis C and antiviral therapy, primary biliary cirrhosis, and Wilson disease as well as the circadian rhythm abnormalities present in cirrhosis and hepatic encephalopathy. The association between chronic liver disease, particularly nonalcoholic fatty liver disease, and sleep-disordered breathing is also reviewed in detail.     

Sulfur amino acid metabolism in hepatobiliary disorders.

Sulfur amino acid metabolism was studied in patients with mild to severe forms of liver dysfunction and compared with that of healthy controls. Patients with mild liver dysfunction (for example, Gilbert's syndrome) had a normal sulfur amino acid metabolism. With increased inflammatory activity and cirrhosis (for example, chronic active hepatitis, alcohol-induced cirrhosis, and hepatic coma) a decreased ability to metabolize methionine (to cysteine, with cystathionine accumulation) and cysteine (to inorganic sulfate, with thiosulfate and N-acetylcysteine accumulation) was found. In contrast, transaminative metabolism of sulfur amino acids was preserved in patients with advanced forms of liver dysfunction, suggesting that transamination of sulfur amino acids is performed not only in the liver but also in extrahepatic tissues. Some implications of these findings are discussed.     

Factors associated with the response to interferon-based antiviral therapies for chronic hepatitis C

Hepatitis C virus(HCV) infection is a major health concern worldwide. Interferon-α(IFN-α) therapy has been the main antiviral treatment for more than 20 years. Because of its established antitumor effects, IFNbased treatments for chronic HCV infection still have a clinical impact, particularly for patients with high risk conditions of developing hepatocellular carcinoma, such as older age and advanced liver fibrosis. As a result of exhaustive research, several viral factors, including NS5 A amino acid mutations such as the IFN sensitivitydetermining region and the IFN/ribavirin resistancedetermining region, and mutations of amino acids in the core protein region(core 70 and 91) were shown to be associated with the response to IFN-α treatment. In addition, among the host factors related to the response to IFN-α treatment, polymorphisms of the interleukin-28 B gene were identified to be the most important factor. In this article, we review the factors associated with the efficacy of IFN-α treatment for chronic HCV infection. In addition, our recent findings regarding the possible involvement of anti-IFN-α neutralizing antibodies in a non-response to pegylated-IFN-α treatment are also described.     

Amino acid imbalance following portal diversion in the rat. The relevance of nutrition and of hepatic function

End-to-end portacaval transposition has previously been shown to produce less hepatocellular dysfunction than end-to-side portacaval shunt in the rat. Liver weight is also significantly reduced after portacaval shunt compared to portacaval transposition and these differences are not abolished by pair-feeding. Histological evidence of CNS damage is also reduced in transposed rats compared to shunted animals. This study examines the amino acid and hormone changes in these models. The characteristic amino acid changes of chronic liver disease (decreased branched-chain and elevated aromatic amino acids) are reproduced in portacaval shunt rats, but not in portacaval transposition. The differences between these groups in the branched-chain amino acids, but not those in the aromatic amino acids, are reduced by pair-feeding. Insulin and glucagon are elevated to a similar extent in both groups. These findings add further support to a role for peripheral amino acid imbalance in the pathogenesis of portal-systemic encephalopathy. Normal liver function, maintained by replacement of portal inflow with systemic blood, appears to minimize both CNS damage and amino acid changes.     

Branched chain amino acids in the management of chronic liver disease. Facts and fantasies

The liver plays a central role in protein and amino acid metabolism. It processes dietary amino acids and reprocesses amino acids released from muscle protein degradation. It utilises amino acids for protein synthesis and gluconeogenesis, regulates the supply of amino acids to peripheral tissues and converts excess amino acids to urea. In patients with liver disease the liver's ability to control both plasma and tissue amino acid fluxes may be seriously disturbed. The resultant changes in amino acid metabolism may be implicated in the genesis of the neuropsychiatric abnormalities and the deterioration in nutritional status commonly observed in patients with hepatic failure. Thus, on theoretical grounds, amelioration of these amino acid abnormalities might benefit patients with liver disease who have hepatic encephalopathy or are malnourished. However, there is, at present, no consensus as to the efficacy, practicality or cost-effectiveness of 'amino acid therapy' in patients with liver disease.     

Pancreatic hormones and amino acid levels following liver transplantation

Glucose intolerance, hyperinsulinemia, peripheral insulin resistance and hyperglucagonemia are common in patients with advanced liver disease. These abnormalities in the plasma levels of the pancreatic hormones, insulin and glucagon have been thought to be responsible, at least in part, for the abnormal plasma ratio of branched-chain amino acids to aromatic amino acids. To evaluate this issue, plasma levels of glucose, insulin, glucagon, C-peptide and the branched-chain and aromatic amino acids were measured before and serially after orthotopic liver transplantation in 9 humans and 5 dogs. The abnormal plasma amino acid levels rapidly improved and achieved normal levels following orthotopic liver transplantation. Insulin levels also became normal following orthotopic liver transplantation, despite enhanced insulin secretion documented by an even further increased level of C-peptide. In contrast, the baseline abnormal plasma glucagon levels which are commonly seen in cirrhotics became even more abnormal following orthotopic liver transplantation. Despite this progressive increase in the abnormally elevated plasma glucagon levels, plasma amino acid levels, both branched-chain and aromatic, became normal. These data demonstrate that before and after orthotopic liver transplantation, there is: (i) no relationship between the changes in the plasma levels of glucagon and changes observed in the plasma level of amino acids; and (ii) plasma insulin and amino acid levels change in the same direction. In addition, these changes in plasma insulin and amino acid levels following orthotopic liver transplantation occur despite enhanced secretion of insulin evidenced by the progressive increase in plasma levels of C-peptide.     

Neuroactive amino acids in hepatic encephalopathy

There is abundant evidence to suggest that alterations of excitatory and inhibitory amino acids play a significant role in the pathogenesis of hepatic encephalopathy (HE) in both acute and chronic liver diseases. Brain glutamate concentrations are reduced in patients who died in hepatic coma as well as in experimental HE, astrocytic reuptake of glutamate is compromised in liver failure and postsynaptic glutamate receptors (both NMDA and non-NMDA subclasses) are concomitantly reduced in density. Recent studies in experimental acute liver failure suggest reduced capacity of the astrocytic glutamate transporter in this condition. Together, this data suggests that neuron-astrocytic trafficking of glutamate is impaired in HE. Other significant alterations of neuroactive amino acids in HE include a loss of taurine from brain cells to extracellular space, a phenomenon which could relate both to HE and to brain edema in acute liver failure. Increased concentrations of benzodiazepine-like compounds have been reported in human and experimental HE. Clinical trials with the benzodiazepine antagonist flumazenil reveal a beneficial effect in some patients with HE; the mechanism responsible for this effect, however, remains to be determined.     

Primary biliary cirrhosis

Primary biliary cirrhosis is a chronic cholestatic liver disease of adults. This disorder is characterised histologically by chronic non-suppurative destruction of interlobular bile ducts leading to advanced fibrosis, cirrhosis, and liver failure. The precise aetiopathogenesis of primary biliary cirrhosis remains unknown, although dysregulation of the immune system and genetic susceptibility both seem to be important. Affected patients are typically middle-aged women with abnormal serum concentrations of alkaline phosphatase. Presence of antimitochondrial antibody in serum is almost diagnostic of the disorder. Identification of primary biliary cirrhosis is important, because effective treatment with ursodeoxycholic acid has been shown to halt disease progression and improve survival without need for liver transplantation. However, therapeutic options for disease-related complications-including fatigue and metabolic bone disease-remain unavailable. Mathematical models have been developed that accurately predict the natural history of primary biliary cirrhosis in individuals. Despite advances in understanding of the disease, it remains one of the major indications for liver transplantation worldwide.     

Correlations between zinc, amino acids and ammonia in liver cirrhosis

In view of the universal metabolic importance of zinc in the organism, it was the purpose of the present work to determine the concentrations of zinc in serum, of amino acids and ammonia in plasma of patients with liver cirrhosis, and investigate that correlations might exist between these substances. The study involved 18 patients with decompensated liver cirrhosis without coma and eleven with coma. The subjects with normal livers were used as controls. While confirming known data (reduced zinc levels, imbalance of plasma amino acids, hyperammonaemia in chronic liver diseases) the findings also revealed correlations between the above substances. A negative correlations existed between zinc and ammonia. Decreases in zinc serum levels were accompanied by increases in plasma ammonia concentrations in hepatic coma (p less than 0.05). Plasma levels of amino acids did not correlate with serum zinc concentrations.     

Branched-chain amino acids as pharmacological nutrients in chronic liver disease

Branched-chain amino acids (BCAAs) are a group of essential amino acids comprising valine, leucine, and isoleucine. A low ratio of plasma BCAAs to aromatic amino acids is a physiological hallmark of liver cirrhosis, and BCAA supplementation was originally devised with the intention of normalizing amino acid profiles and nutritional status. However, recent studies on BCAAs have revealed that, in addition to their role as protein constituents, they may have a role as pharmacological nutrients for patients with chronic liver disease. Large-scale, multicenter, randomized, double-blinded, controlled trials on BCAA supplementation have been performed in Italy and Japan, and results demonstrate that BCAA supplementation improves not only nutritional status, but also prognosis and quality of life in patients with liver cirrhosis. Moreover, accumulating experimental evidence suggests that the favorable effects of BCAA supplementation on prognosis may be supported by unforeseen pharmacological actions of BCAAs. This review summarizes the possible effects of BCAAs on albumin synthesis and insulin resistance from clinical and basic viewpoints. We also review the newly discovered clinical impact of BCAAs on hepatocellular carcinoma and the prognosis and quality of life of patients with liver cirrhosis.     

Deep vein thrombosis and pulmonary embolism in cirrhotic patients:Systematic review

Patients with liver cirrhosis were traditionally believed to be protected against development of blood clots.Lately,studies have shown that these patients may probably be at an increased risk of venous thrombotic complications.Although the hemostatic changes in the chronic liver disease patients and the factors that may predict bleeding vs thrombotic complications remains an area of active research,it is believed that the coagulation cascade is delicately balanced in these patients because of parallel reduced hepatic synthesis of pro and anticoagulant factors.Thrombotic state in cirrhotic patients is responsible for not only portal or non-portal thrombosis[deep vein thrombosis(DVT)and pulmonary embolism(PE)];it has also been associated with progression of liver fibrosis.The use of anticoagulants in cirrhosis patients is a challenging,and often a scary situation.This review summarizes the current literature on the prevalence of venous thrombosis(DVT and PE),risk factors and safety of prophylactic and therapeutic anticoagulation in patients with chronic liver disease.