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Biomedical subjects

Y F Liaw

Publications and source records attributed to Y F Liaw.

At least 19 recordsLinked to original sources
PubMed1996

L-myc, GST M1 genetic polymorphism and hepatocellular carcinoma risk among chronic hepatitis B carriers.

In order to assess associations between the genetic polymorphism of L-myc and glutathione S-transferase M1 (GST M1) and the risk of hepatocellular carcinoma (HCC), a total of 46 surgically treated HCC patients who were seropositive in hepatitis B surface antigen (HBsAg) and 88 HBs-Ag positive controls were recruited for this study. L-myc and GST M1 genetic polymorphism was examined using a polymerase chain reaction-based restriction fragment length polymorphism assay on DNA extracted from liver and peripheral blood samples. There was no significant difference in GST M1 genotypes between HCC patients and matched controls. A gene dosage trend of association with HCC risk was observed for L-myc genotype. The dose-response relationship remained statistically significant in the multiple logistic regression analysis.

Age Factors↗
PubMed1996

Purification and characterization of a naturally processed hepatitis B virus peptide recognized by CD8+ cytotoxic T lymphocytes.

In vitro studies in patients with hepatitis B virus (HBV) infection have suggested that hepatocytolysis induced by CD8+ cytotoxic T lymphocytes (CTLs) is the most important effector pathway in eliminating infected cells. The recognition is implicated in the endogenously processed HBV antigens in the context of HLA class I molecules presented on the liver cell membrane. However, the naturally occurring HBV peptide antigens have not yet been demonstrated. We report here that a naturally processed peptide antigen P2 was isolated from HLA class I molecules of HBV-infected liver cell membrane. The P2 peptide exhibited the activity of sensitizing target cells for lysis by CD8+ CTLs. The P2 sequence (YVNVNMGLK) purified from liver tissue was in concordance with that encoded by the viral genome for the HBV nucleocapsid antigen or HBcAg 88-96. P2 peptide could also be isolated from the EBV-transformed B cells that were transfected by HBcAg-expressing vector. The P2 epitope, sharing the HLA-A11 binding motifs, was recognized by HLA-A11-restricted CD8+ CTLs. The data provided direct evidence that, in hepatitis B patients, antigenic peptides of HBV were processed by hepatocytes, presented with the class I MHC molecules, and recognized by CD8+ CTLs.

Adult↗
PubMed1996

Characterization of nuclear localization of a hepatitis B virus precore protein derivative P22.

Both of hepatitis B virus core protein and a precore protein derivative, named P22, have been shown to localize in the nucleus. Although P22 has ten additional amino acid residues at its amino-terminus, both proteins contain the same nuclear localization signal. In order to understand the mechanism that regulates the activity of this signal, we have studied the nuclear localization of P22 and compared it with that of core protein. It was found that both cytosolic and nuclear fractions of P22 were phosphorylated but to a lesser extent when compared with cytosolic core protein. This distinction was likely attributed to different conformations between these two proteins since the density gradient analysis revealed a different particle formation for P22 in the cytosol. When expressed in Vero cells synchronized by serum deprivation, P22 remained in the cytosol during G0 and G1 phases, accumulated gradually in the nucleus during S phase, and largely localized in the nucleus when cells were confluent. On the other hand, the core protein was transported into the nucleus during mid-G1 phase, shuttled back to the cytosol in S phase and again accumulated in the nucleus when cells were confluent. Interestingly, when aphidicolin was used to arrest the cells in late G1 phase, both proteins were found to accumulate in the nuclei. These results indicated that although both P22 and core proteins possessed the same nuclear localization signal, the cellular regulation of their nuclear transport was not identical and might involve different molecular mechanisms.

Animals↗
PubMed1996

Severe clinical rebound upon withdrawal of corticosteroid before interferon therapy: incidence and risk factors.

To analyse the incidence and risk factors of clinical rebound and hepatic decompensation during or upon withdrawal of prednisolone pretreatment before interferon (IFN) therapy, two series of Taiwanese patients with chronic viral hepatitis from two independent randomized controlled trails were compared. Group 1 included 41 patients with chronic hepatitis B who were pretreated with daily prednisolone (30 mg) for 3 weeks, 15 mg for 1 week and no prednisolone for 2 weeks prior to lymphoblastoid IFN therapy. Group 2 consisted of 59 patients with chronic hepatitis B who were pretreated with daily prednisolone (40 mg) for 2 weeks, 30 mg prednisolone for 2 weeks, 20 mg prednisolone for 2 weeks and no prednisolone for 2 weeks prior to INF alpha-2a therapy. Clinical rebound developed more frequently in group 2 (67.8%) than in group 1 patients (41.5%; P < 0.01). The peak serum transaminase levels of group 1 and 2 patients during clinical rebound were similar. Icteric and symptomatic clinical rebound occurred in four (one cirrhotic) group 2 patients. The incidence of hepatic decompensation was 3.4% in group 2 patients, or 5.0% in group 2 patients with clinical rebound. Patients pretreated with a higher dose (40 mg) of prednisolone (odds ratio 3.0; 95% CI 1.3-6.6; P < 0.01) and non-cirrhotic patients (odds ratio 6.2; 95% CI 1.2-32.1; P < 0.02) tended to suffer from clinical rebound more frequently. However, once clinical rebound develops in cirrhotic patients, the relative risk of decompensation is 16 times that of non-cirrhotic patients. These results suggest that clinicians should be cautious in prescribing a short course of corticosteroids for patients with chronic viral hepatitis, because hepatic decompensation might occur in Oriental people with or without cirrhosis.

Adult↗
PubMed1996

Chronic hepatitis B carriers with null genotypes of glutathione S-transferase M1 and T1 polymorphisms who are exposed to aflatoxin are at increased risk of hepatocellular carcinoma.

This study was carried out to elucidate the effect of glutathione S-transferase (GST) Ml and Tl polymorphisms on the aflatoxin-related hepatocarcinogenesis among chronic carriers of hepatitis B surface antigen (HBsAg). A total of 32 newly diagnosed hepatocellular carcinoma (HCC) cases and 73 age-matched controls selected from a cohort of 4,841 chronic HBsAg carriers who had been followed for 5 years were studied. The level of aflatoxin B1 (AFB1)-albumin adducts in their serum samples collected at the recruitment was examined by competitive enzyme-linked immunosorbance assay, and genotypes of GST M1 and T1 were determined by PCR. There was a dose-response relationship between serum level of AFB1-albumin adducts and risk of HCC. The biological gradients between serum AFB1-albumin adducts level and HCC risk were observed among chronic HBsAg carriers who had null genotypes of GST M1 and/or T1 but not among those who had non-null genotypes. The multivariate-adjusted odds ratios of developing HCC for those who had low and high serum levels of AFB1-albumin adducts compared with those who had a undetectable adduct level as the referent (odds ratio = 1.0) were 4.1 and 12.4, respectively, for HBsAg carriers with null GST M1 genotype (P < .01, on the basis of the significance test for trend); 0.7 and 1.4 for those with non-null GST Ml genotype (P = .98); 1.8 and 10.2 for those with null GST T1 genotype (P < .05); and 1.3 and 0.8 for those with non-null GST T1 genotype (P = .93). The interaction between serum AFB1-albumin adduct level and polymorphisms of GST M1 and T1 was at marginal statistical significance levels (.05 < P < .10).

Adult↗
PubMed1995

A single serine mutation on the nuclear localization signal of hepatitis B virus core protein abolishes the inhibition of nuclear transport by surface proteins.

The nuclear localization signal of hepatitis B virus core protein contained three SPRRR motifs. Substitution of a single serine residue on the third SPRRR motif enhanced significantly the nuclear localization of core protein. By performing immunofluorescence staining assays and subcellular fractionation experiments, it was demonstrated that although nuclear transport of the wild type core protein was markedly suppressed by co-expression of hepatitis B virus surface proteins, nuclear transport of this serine mutant protein was not affected. These results indicated that the serine residue in the SPRRR motifs played an important role in regulating the nuclear transport of core protein and the interaction between core and surface proteins.

Animals↗
PubMed1995

Serum carboxy terminal propeptide of type I procollagen to amino terminal propeptide of type III procollagen ratio is a better indicator than each single propeptide and 7S domain type IV collagen for progressive fibrogenesis in chronic viral liver diseases.

Twenty chronic viral hepatitis patients, mainly with hepatitis B related with progression to liver cirrhosis were included for an assay of serum collagen markers: PICP (carboxy terminal propeptide of type I procollagen), PIIINP (amino terminal propeptide of type III procollagen), and 7S-IV (7S-domain type IV collagen). PICP is increased in 20% of chronic hepatitis patients with a mean of 190.3 ng/ml, which is not different from that of the follow-up concentration in liver cirrhosis, where 35% of cases were abnormal with a mean of 220.5 ng/ml. The serum level and percent of abnormality of PIIICP in chronic hepatitis and in liver cirrhosis are 23.5 ng/ml vs 14.8 ng/ml and 90% vs 100%, respectively (P > 0.05). PICP/PIIINP is significantly higher during liver cirrhosis (15.11 vs 10.08, P < 0.05). PICP during chronic hepatitis is not related to serum biochemical changes, while PICP during liver cirrhosis and PIIINP are correlated with hepatic enzymes. 7S-IV in chronic hepatitis and in liver cirrhosis is 14.0 ng/ml vs 10.9 ng/ml, respectively; both were positively correlated with hepatic enzymes. These results suggest that PICP/PIIINP is a better indicator of hepatic fibrogenesis than either PICP or PIIINP alone in viral hepatitis. A ratio of more than 12 is suggestive of liver cirrhosis.

Adult↗
PubMed1995

Prevalence and prognostic significance of bacterascites in cirrhosis with ascites.

The prevalence and prognostic significance of bacterascites (BA) were prospectively studied in 443 predominantly HBsAg-positive cirrhotic patients with ascites. Spontaneous bacterial peritonitis (SBP), culture-negative neutrocytic ascites (CNNA), and BA were identified in 12.4%, 8.4%, and 10.8%, respectively. Of these, 67%, 70%, and 71%, respectively, had peritonitis-related signs or symptoms. Among patients with SBP or CNNA, the clinical and laboratory data showed no significant difference between the symptomatic and asymptomatic groups. In contrast, among the patients with BA, the symptomatic group had significantly higher levels of serum total bilirubin and prolonged prothrombin time and significantly lower levels of ascitic fluid total protein than the asymptomatic group. Furthermore, the clinical and laboratory data were relatively similar between patients with asymptomatic BA and those with sterile ascites. In contrast, patients with SBP, CNNA, or symptomatic BA exhibited significantly more severe degrees of liver disease and significantly lower levels of ascitic fluid total protein than those with sterile ascites. There was no statistically significant difference between SBP and bacterascites regarding flora. All patients with SBP, CNNA, or symptomatic BA received antibiotic treatment immediately after paracentesis, as did six of the 14 patients with asymptomatic BA for concurrent respiratory or urinary tract infection, while the remaining eight patients with asymptomatic BA were followed clinically without treatment. Repeated paracentesis in the latter revealed no evidence of SBP or CNNA. The in-hospital mortality for sterile ascites was 22.8%, significantly lower than the 54.5% for SBP, 43.2% for CNNA, and 50% for symptomatic BA, but similar to the 21.4% for asymptomatic BA.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascites↗
PubMed1995

Serum levels of interferon-alpha and -gamma in acute and chronic hepatitis B virus infection.

To evaluate the potential implication of in vivo interferon production in the pathogenesis of different forms of acute and chronic hepatitis B virus infection, serum levels of interferon-alpha and -gamma were measured using immunoassay techniques in 20 patients with acute hepatitis B who subsequently cleared the virus (group Ia), 8 patients with acute hepatitis B who became HBsAg carriers (group Ib), 55 patients with chronic hepatitis B (group II), and 15 healthy controls. None of the controls had interferon-alpha or -gamma detectable in serum, while 15% and 100% of group Ia patients, 25% and 100% of group Ib patients, and 22% and 15% of group II patients, had raised serum levels of interferon-alpha and -gamma, respectively. Serum interferon-gamma was detected significantly more frequently in group Ia and Ib patients than in controls and in group II patients. Among patients with acute hepatitis B, serum levels of interferon-alpha and -gamma showed no significant difference between group Ia and group Ib patients. Among patients with chronic hepatitis B, interferon-alpha was detected significantly more frequently in patients with serum HBV-DNA (31.4% or 11/35) than in those without (5% or 1/20), whereas interferon-gamma was detected significantly more frequently in patients with chronic active hepatitis (28% or 7/25) than in those with chronic persistent hepatitis (3.3% or 1/30). In conclusion, in acute hepatitis B, serum levels of interferon-alpha and -gamma did not show a significant difference between patients who subsequently cleared the virus and those who became HBsAg carriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Detection and partial sequence analysis of Helicobacter pylori DNA in the bile samples.

The existence of Helicobacter pylori in the biliary tract was investigated. Seven bile samples were included in this study. Among them, six bile samples were collected by percutaneous transhepatic cholangiodrainage and the other by needle aspiration during cholecystectomy. Using nested PCR with two sets of primers homologous to the urease A gene, Helicobacter pylori DNA was detected. Three samples, one from a patient with advanced gastric cancer involving the pancreatic head and two from patients with pancreatic head tumor, were found to be positive for Helicobacter pylori DNA. On the other hand, three samples from patients with cholangiocarcinoma and one from a patient with chronic cholecystitis were all negative. To further verify the specificity of our PCR analysis, partial sequences of the PCR products from the three positive samples were analyzed by direct sequencing. Several silent mutations and a missense mutation (AAA to AGA; Lys-164 to Arg-164) were identified in the urease A gene. We conclude that Helicobacter pylori DNA can be easily detected in the bile samples. The possibility of asymptomatic cholangitis caused by this organism requires further investigation.

Adult↗
PubMed1995

Cytochrome P450 2E1 and glutathione S-transferase M1 polymorphisms and susceptibility to hepatocellular carcinoma.

BACKGROUND & AIMS: Genetic polymorphisms in enzymes involved in carcinogen metabolism have been found to influence susceptibility to cancer. The aim of this study was to examine whether cytochrome P450 2E1 (CYP2E1) and/or glutathione S-transferase M1 (GSTM1) genetic polymorphisms were related to susceptibility to hepatocellular carcinoma (HCC). METHODS: Genotyping of CYP2E1 and GSTM1 was performed using the polymerase chain reaction on peripheral white blood cell DNA from 30 patients with HCC and 150 controls nested in a cohort study. RESULTS: The c1/c1 genotype of CYP2E1, detected by PstI or RsaI digestion, was found in 83.3% of patients with HCC and in 63.3% of controls (P = 0.034). Homozygosity for the c1/c1 genotype significantly increased the risk of developing HCC in cigarette smokers (P = 0.001) but posed no increased risk in those who never smoked. The HCC risk associated with cumulative exposure to cigarette smoke was also more striking in individuals who carried the c1/c1 genotype. Habitual alcohol drinking modified the HCC risk of cigarette smoking among those with the c1/c1 genotype. No association with the risk of HCC was observed for the DraI polymorphism of CYP2E1 or for the GSTM1-null genotype. CONCLUSIONS: Polymorphisms of CYP2E1 may play an important role in cigarette smoking-related hepatocarcinogenesis.

Adult↗
PubMed1995

Subcellular localization of hepatitis B core antigen in relation to hepatocyte regeneration in chronic hepatitis B.

BACKGROUND & AIMS: To test whether the dominant cytoplasmic expression of hepatitis B core antigen (HBcAg) in active chronic hepatitis B is secondary to liver damage and regeneration, the relationship between subcellular localization of HBcAg, liver inflammatory activity, and hepatocyte regeneration in chronic hepatitis B was studied. METHODS: Correlation of the clinical and laboratory data with the topographical distribution of HBcAg was studied in 30 patients. The subcellular localization of HBcAg in relation to hepatocyte cell cycles was studied by double immunostaining of HBcAg and proliferating cell nuclear antigen. RESULTS: Patients with predominant cytoplasmic HBcAg had significantly higher levels of biochemical and histological activities and proliferating cell nuclear antigen expression than patients with predominant nuclear HBcAg. The levels of proliferating cell nuclear antigen expression correlated positively with biochemical and histological activities and degrees of cytoplasmic HBcAg expression but negatively with degrees of nuclear HbcAg expression. Proliferating cell nuclear antigen expression was shown in 49% of hepatocytes with cytoplasmic HBcAg but in only 2% of hepatocytes with nuclear HBcAg. CONCLUSIONS: These findings suggested that, following liver damage, the regeneration of surviving hepatocytes might cause the shift of intracellular HBcAg from nucleus to cytoplasm. As a result, the extent of nuclear HBcAg expression reduces with concomitant increase in cytoplasmic HBcAg expression.

Adolescent↗
PubMed1995

Role of hepatitis C virus in dual and triple hepatitis virus infection.

Hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) share same transmission routes, thus dual or triple infection may occur and even persist in the same patients. A significant amount of literature has accumulated since the advent of HCV assays. It is pertinent to review and evaluate the clinical and virological significance of HCV in multiple hepatotropic viral infection. The reported series on seroprevalence of HCV indicate that HCV is found in more than 10% of HBV- or HDV-infected patients worldwide. Of the patients with dual or triple infection involving HCV, those having coreplication of viruses tend to have severe and progressive liver disease that is resistant to interferon therapy, in contrast with patients having a single virus infection. Paradoxically, dual or triple hepatitis virus infections are associated with viral interference. In particular, HCV exerts a suppressive effect on HBV and HDV and may enhance seroclearance of HBV antigens or even usurp the role of preexisting virus as the agent for continuing hepatitis. Although HBV and HDV may also suppress HCV, it appears to be less effective. These findings clearly suggest the necessity of monitoring patients with HBV or HDV infections. In view of complex dynamism of viral interaction in multiple hepatotropic virus infection, the importance of HCV assay in the clinical studies can not be overemphasized. The basic mechanisms that regulate the viral interactions, in particular the impact of HCV in dual or triple virus infections, remain to be investigated.

Antiviral Agents↗
PubMed1995

Helicobacter pylori in cirrhotic patients with peptic ulcer disease: a prospective, case controlled study.

BACKGROUND: There is an increased prevalence of peptic ulcer disease in patients with liver cirrhosis, but the role of Helicobacter pylori is unclear. METHODS: lgG antibodies against H. pylori were measured in 60 patients with compensated liver cirrhosis, in 60 sex- and age-matched patients with compensated liver cirrhosis, and in 60 normal controls. All patients received panendoscopic examinations to search for the evidence of esophageal varices, congestive gastropathy, and peptic ulcers. RESULTS: Duodenal ulcers were more common in compensated and decompensated cirrhotic patients (16.7% and 13.3%, respectively) than in normal controls (3.3%, p < 0.05). Gastric ulcers were more frequent in decompensated (15.0%) than compensated cirrhotic patients and normal controls (3.3% and 1.7%, respectively, p < 0.05). The prevalence of H. pylori was not statistically different among the three groups (normal 60.0%, compensated 61.7%, and decompensated, 75.0%; p > 0.05). The prevalence of H. pylori also showed no statistical differences in respect to duodenal ulceration (100%, 80%, and 87.5%, respectively, p > 0.05). The prevalence of H. pylori did not differ significantly in relation to the presence or absence of esophageal varices (68.4% vs 100% if no varices, p = 0.04) and in the presence of congestive gastropathy (50.0 vs 94.7%, p = 0.03). CONCLUSIONS: The prevalence of peptic ulcer was increased in cirrhotic patients, but the prevalence of H. pylori was similar in compensated cirrhotic patients, decompensated cirrhotic patients, and normal controls. The frequency of non-H. pylori-associated peptic ulcers in cirrhotic patients was increased in the presence of esophageal varices or congestive gastropathy.

Case-Control Studies↗
PubMed1995

Simultaneous acute hepatitis B virus and hepatitis C virus infection leading to fulminant hepatitis and subsequent chronic hepatitis C.

A 22-year-old male Taiwanese was admitted to the hospital for acute hepatitis B associated with fulminant hepatic failure. After receiving supportive treatment, the patient's clinical condition improved and the results of liver function tests (including prothrombin time) gradually improved. However, in spite of seroconversion from hepatitis B surface antigen to antibody, hepatitis relapsed and serum alanine aminotransferase levels were persistently abnormal during the 3-year follow-up period. Liver biopsy performed 2 years after the onset of illness revealed chronic hepatitis. A retrospective review of the patient's serological test results revealed hepatitis C virus (HCV) RNA and the development of antibodies to HCV during the acute phase of illness as well as the persistence of HCV RNA during follow-up. Thus, we serologically and virologically proved that our patient had simultaneous acute infections with hepatitis B and C viruses and that these infections led to fulminant hepatic failure, relapse of hepatitis, and chronic hepatitis C.

Acute Disease↗
PubMed1995

Membrane staining for hepatitis B surface antigen on hepatocytes: a sensitive and specific marker of active viral replication in hepatitis B.

AIMS--To test the hypothesis that membranous staining of hepatitis B surface antigen (HBsAg) on the hepatocyte is a marker of active viral replication in chronic hepatitis B virus (HBV) infection. METHODS--Intrahepatic expression of HBsAg and hepatitis B core antigen (HBcAg) was studied by indirect immunofluorescence on frozen sections of liver specimens from 75 patients with chronic hepatitis B, and the results were correlated with serum levels of HBV-DNA assayed by spot hybridisation. RESULTS--Hepatocyte HBcAg was detected in all of 20 patients with serum levels of HBV-DNA > 1000 pg/ml, 18 (75%) of 24 patients with levels of HBV-DNA < or = 1000 pg/ml, and two (6.5%) of 31 patients without detectable serum HBV-DNA. The concordance between hepatocyte HBcAg and serum HBV-DNA was 89.3% (67/75). There were six patients (8%) who had detectable serum HBV-DNA but without hepatocyte HBcAg, and two patients (2.7%) who had detectable hepatocyte HBcAg but without serum HBV-DNA. Membranous staining of HBsAg associated with variable degrees of cytoplasmic HBsAg was found in all but one of 44 patients with serum HBV-DNA, irrespective of the levels, but in none of the 31 patients without serum HBV-DNA. Of the latter, HBsAg was distributed solely in the cytoplasm. In addition, there is an inverse correlation between serum levels of HBV-DNA and the degrees of cytoplasmic staining of HBsAg. The concordance between membranous staining fo HBsAg and serum HBV-DNA was 98.7% (74/75), significantly higher than that between hepatocyte HBcAG and serum HBV-DNA. CONCLUSIONS--Membranous staining of HBsAg on the hepatocyte correlated excellently with serum HBV-DNA and thus can be recognised as a sensitive and specific marker of active hepatitis B virus replication.

Adult↗
PubMed1995

Cellular immune responses in patients with dual infection of hepatitis B and C viruses: dominant role of hepatitis C virus.

Several lines of evidence have suggested that immune mechanisms are involved in the pathogenesis of hepatitis B virus (HBV)- and hepatitis C virus (HCV)-related hepatitis. Study of patients with dual HBV and HCV infection raises the question of which is etiologically more relevant in determining the liver cell damage. To address this issue, proliferation of peripheral blood mononuclear cells (PBMCs) in response to a panel of HBV and HCV antigens was assayed in 13 patients with chronic dual hepatitis B and C, 7 patients with chronic hepatitis B, 7 patients with chronic hepatitis C, and 6 patients with hepatitis B surface antigen (HBsAg) carrier state. Although HBV or HCV hepatitis patients had a significant response to HBV or HCV antigens, respectively, the patients with dual hepatitis B and C exclusively responded to HCV antigens, but not to HBV antigens. One patients who was seropositive for both HBV-DNA and HCV-RNA showed a low response to HBV antigens initially but lost the response 3 months later and became responsive to more HCV antigens. These findings suggest that HCV has a dominant role in the immune response of the patients with dual HBV and HCV infection.

Adolescent↗