Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A quantitative competitive RNA polymerase chain reaction (QC-PCR) assay was developed for measuring absolute levels of hepatitis C virus (HCV) RNA in the sera of 121 viremic persons, including 64 asymptomatic blood donors, 39 symptomatic patients referred for treatment of chronic hepatitis C, and 18 patients with end-stage liver disease referred for liver transplantation. Mean HCV RNA levels (log molecules per milliliter) were lowest among blood donors with normal alanine aminotransferase (ALT) values (5.8 +/- 1.5), higher among blood donors with elevated ALT (6.9 +/- 0.8) and clinic patients with chronic active hepatitis (6.9 +/- 0.7), and highest among patients with cirrhosis (7.1 +/- 0.8) or end-stage liver disease (7.6 +/- 1.0). High-titer viremia ( > or = 7.5 logs/mL) was more frequent among patients with end-stage liver disease (14/18; 78%) than either blood donors (10/64; P < .001) or patients with chronic active hepatitis (7/26; P < .001). Thus, 121 (94.5%) of 128 anti-HCV-positive persons were viremic. QC-PCR may be valuable for monitoring HCV infection status and selecting individuals for therapy.
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PMID:Assessment of hepatitis C virus RNA levels by quantitative competitive RNA polymerase chain reaction: high-titer viremia correlates with advanced stage of disease. 819 99

The molecular role of hepatitis C virus (HCV) in liver disease has yet to be clarified. In this study, we analyzed the relationship of HCV replication with mRNA expression of growth factors and mutation of tumor suppressor gene, ie, transforming growth factor-beta 1 (TGF-beta 1), which promotes cirrhotic changes; TGF-alpha, insulin-like growth factor-II (IGF-II), which are both related to hepatocyte transformation; and tumor suppressor gene p53, which is associated with HCC progression. A semiquantitative RNA polymerase chain reaction (RNA-PCR) was used to analyze genetic expression in 31 cirrhotic liver specimens from patients with HCV. In order to detect HCV replication, the minus-strand RNA of HCV, which serves as a template for the synthesis of genomic plus-strand RNA, was examined. The expression of the growth factors was semiquantified by RNA-PCR, and the mutation of p53 was detected using PCR-single-strand conformation polymorphism. According to the semiquantitative analysis, HCV replication was not associated with the expression of TGF-beta 1 but was significantly so with the overexpression of TGF-alpha (r = 0.74) and IGF-II (r = 0.65) in the HCV-positive cirrhotic livers. No mutation of p53 was recognized in any of the samples. Our investigation thus suggested that the replication of HCV might mediate the coexpression of TGF-alpha and IGF-II and act as a possible initiating factor for hepatocarcinogenesis.
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PMID:Hepatitis C virus replication is associated with expression of transforming growth factor-alpha and insulin-like growth factor-II in cirrhotic livers. 856 58

The significance of a positive hepatitis C virus (HCV) screening test in asymptomatic blood donors with normal or near normal aminotransferases was studied along with the usefulness of HCV RNA polymerase chain reaction (PCR) testing for predicting chronic hepatitis in these individuals. One hundred and thirty-nine volunteer blood donors who were found positive by second generation ELISA for antibodies to HCV agreed to participate in the study. Thirty-one of them were supplemental test positive, had ALT values less than twice normal, and were followed over a minimum of 12 months. Thirteen consented to percutaneous liver biopsy and also had HCV RNA determination by PCR. Ten of the 13 subjects were positive for HCV RNA by PCR. Of the nine who were positive for HCV RNA and had adequate tissue for evaluation, seven had evidence of chronic hepatitis, three with limiting plate necrosis. Lobular inflammation was similar in severity to that found in the portal region. In addition, two had periportal fibrosis, and one had bridging fibrosis. Of the three subjects who were negative for HCV RNA, only one had portal inflammation which was limited to the portal region. None of these three had lobular changes, or periportal or bridging fibrosis. Of the three normal biopsies, two were from subjects who were negative for HCV RNA. The sensitivity and specificity of HCV RNA testing for chronic hepatitis was 87.5% and 50%, respectively, yielding an overall accuracy of 75%. We conclude that asymptomatic blood donors with antibodies to HCV, normal or mildly elevated liver tests, and HCV RNA may have abnormal liver histology indicating the potential for progressive liver disease. HCV RNA testing by PCR may be clinically useful as a noninvasive means to discriminate between those with and without chronic liver disease.
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PMID:Liver histology in anti-HCV-positive persons with normal or minimally elevated aminotransferases. 858 5

A commercially available kit, Amplicor, was compared with a locally developed nested reverse-transcriptase (RT) PCR for qualitative detection of HCV-RNA. Sixty-one serum samples from sixty-one patients with liver disease, and 60 samples from 60 hemophiliacs without symptoms, but known to have been heavily exposed to hepatitis C virus, were investigated. There was a high degree of concordance between the two diagnostic tests (97%), the Amplicor kit being slightly more sensitive than the in-house PCR, when evaluated using serial dilutions of samples showing discrepant results. The relationship between viremia and abnormal ALT levels was studied in the two groups of patients. Among those with chronic liver disease, 8.3% of patients with viremia had normal ALT levels, whereas transaminases were normal in 20% of hemophiliacs with viremia. This points to ALT as being a poor marker of ongoing viral replication.
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PMID:Viremia in chronic hepatitis C patients evaluated by the Amplicor RT-PCR, a nested RT-PCR, and transaminase levels. 953 67

GB virus C (GBV-C) is a newly discovered RNA virus related to the Flaviviridae family. Although GBV-C is not yet associated with any cause of liver disease, a humoral immune response against the GBV-C envelope 2 (E2) protein has been observed. Therefore, we studied the prevalence and clinical relevance of GBV-C RNA and anti-E2 antibodies in patients undergoing orthotopic liver transplantation (OLT). In addition, we tested whether the prevalence of anti-E2 antibodies may protect against GBV-C infection. Of the 182 liver recipients included in this study, 117 of these were evaluated for GBV-C recurrence or de novo infection. GBV-C RNA was detected in sera or plasma using single-tube, reverse-transcriptase polymerase chain reaction, and anti-E2 antibody was detected by enzyme immunoassay (EIA). Cumulative patient and graft survival was tested by using Kaplan-Meier analysis. The independence of prognostic values was assessed by using Cox regression analysis. Before OLT, GBV-C RNA and anti-E2 were detected in 4.0% to 28.6% and 10.0% to 68.8%, respectively, of patients suffering from different forms of chronic liver diseases. GBV-C reinfection after OLT was determined in 85.7%. Of the patients without evidence of exposure to GBV-C before OLT, 30 of 65 (46.2%) became GBV-C RNA positive after OLT. None of the 38 patients who were anti-E2 antibody positive before OLT became GBV-C RNA positive after OLT. Neither patient nor graft survival was significantly affected by the presence of either GBV-C RNA or anti-E2 antibody before OLT. Our data indicate that 1) GBV-C RNA positive patients have a high risk of reinfection after OLT, and 2) the presence of anti-E2 antibodies before OLT is associated with an absence of GBV-C infection after OLT, which may indicate a protective role of anti-E2 antibodies.
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PMID:Antibodies against the GB virus C envelope 2 protein before liver transplantation protect against GB virus C de novo infection. 969

The outcome of hepatitis C virus (HCV) infection on patient and graft survival after orthotopic liver transplantation (OLT) has been controversial. An earlier experience with a higher dose of tacrolimus (>/=0.1 mg/kg/d intravenously and >/=0.2 mg/kg/d orally) was associated with a worse clinical outcome in patients infected with HCV. The clinical outcome of 183 liver transplant recipients with end-stage liver disease (ESLD) secondary to HCV infection (HCV group) was compared with a contemporary cohort of 556 patients with HCV infection who underwent transplantation for nonviral, nonmalignant ESLD (control group). All patients were prospectively screened for anti-HCV antibodies and HCV RNA by reverse-transcriptase polymerase chain reaction. All OLT patients were receiving low-dose tacrolimus immunosuppression. Cumulative patient survival rates for the HCV group were 80% after 1 year and 75% after 3 years compared with rates of 84% and 78%, respectively, in the control group (P = .452). Primary graft survival rates at the same time intervals for the HCV group and the control group were 72% and 77.5% at 1 year and 67% and 72% at 3 years, respectively (P = .144). The incidence of re-transplantation (re-OLT) in the HCV group and the control group was 12.6% and 10.4%, respectively (P = .42). Chronic HCV infection as an indication for OLT with a lower dose of tacrolimus immunosuppression (</=0.05 mg/kg/d intravenously and </=0.1 mg/kg/d orally) is associated with a similar patient and graft survival as those without HCV infection.
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PMID:Clinical outcome of patients infected with hepatitis C virus infection on survival after primary liver transplantation under tacrolimus. 979 Nov 54

Studies aimed at correlating the intrahepatic hepatitis C virus (HCV)-RNA level and anatomo-clinical features have been difficult because of sensitivity and specificity shortcomings of available techniques. We titered the genomic- and minus-strand HCV RNAs by a strand-specific, semiquantitative, genotype-independent reverse-transcriptase polymerase chain reaction (RT-PCR) in the liver tissue of 61 patients with chronic hepatitis C. Findings were correlated with the levels of HCV RNA in the serum, the HCV genotype, the expression of intrahepatic HCV antigens, the histological activity (using separate scores for the lobular and the portal/periportal necroinflammatory activity and for the fibrosis), and the response to interferon alfa (IFN-alpha) treatment. Genomic- and minus-strand HCV RNA were detected in 59 and 57 liver specimens, respectively. The HCV-RNA level in the serum correlated with the genomic-strand, but not with the minus-strand, HCV-RNA titer in the liver. No correlations were found between either strand of the intrahepatic HCV RNA and the level of expression of HCV antigens in the liver, or with the grading/staging of the underlying liver disease. The response to IFN-alpha treatment could be predicted by the serum HCV-RNA level and genotype, but not by the intrahepatic level of genomic- or minus-strand HCV RNA. These results suggest that, although the detection of the minus-strand HCV RNA reliably identifies the presence of replicating HCV in its target organ, the quantitative measurement of viremia remains the clinically meaningful "golden standard" for assessing the level of HCV replication.
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PMID:Detection of genomic- and minus-strand of hepatitis C virus RNA in the liver of chronic hepatitis C patients by strand-specific semiquantitative reverse-transcriptase polymerase chain reaction. 991 32

The molecular pathogenesis of alcoholic liver disease (ALD) is not well understood. Gene expression profiling has the potential to identify new pathways and altered molecules in ALD. Gene expression profiles of ALD in a baboon model and humans were compared using DNA arrays. Reverse transcriptase-polymerase chain reaction and immunohistochemistry were used for downstream analysis of array results. cDNA array analysis revealed differential expression of several novel genes and pathways in addition to genes known to be involved in ALD pathogenesis. Overall gene expression profiles were similar in both species, with a majority of genes involved with fibrogenesis and xenobiotic metabolism, as well as inflammation, oxidant stress, and cell signaling. Genes associated with stellate cell activation (collagens, matrix metalloproteinases, tissue inhibitors of matrix metalloproteinase) were up-regulated in humans. Decreased expression of several metallothioneins was unexpected. Fourteen molecules related to the annexin family were up-regulated, including annexin A1 and A2. Immunofluorescence revealed a marked overexpression of annexin A2 in proliferating bile duct cells, hepatocyte cell surface, and selective co-localization with CD14-positive cells in human ALD. The gene expression profile of ALD is dominated by alcohol metabolism and inflammation and differs from other liver diseases. Annexins may play a role in the progression of fibrosis in ALD.
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PMID:Gene expression profiling of alcoholic liver disease in the baboon (Papio hamadryas) and human liver. 1463 4

Since effective cell sourcing is a major challenge for the therapeutic management of liver disease and liver failure, embryonic stem (ES) cells are being widely investigated as a promising source of hepatic-like cells with their proliferative and pluripotent capacities. Cell-cell interactions are crucial in embryonic development modulating adhesive and signaling functions; specifically, the cell-cell adhesion ligand, cadherin is instrumental in gastrulation and hepatic morphogenesis. Inspired by the role of cadherins in development, we investigated the role of expression of E-cadherin in cultured murine ES cells on the induction of hepatospecific phenotype and maturation. The cadherin-expressing embryonic stem (CE-ES) cells intrinsically formed pronounced cell aggregates and cuboidal morphology whereas cadherin-deficient cadherin-expressing embryonic stem (CD-ES) cells remained more spread out and corded in morphology. Through controlled stimulation with single or combined forms of hepatotrophic growth factors; hepatocyte growth factor (HGF), dexamethasone (DEX) and oncostatin M (OSM), we investigated the progressive maturation of CE-ES cells, in relation to the control, CD-ES cells. Upon growth factor treatment, the CE-ES cells adopted a more compacted morphology, which exhibited a significant hepatocyte-like cuboidal appearance in the presence of DEX-OSM-HGF. In contrast, the CD-ES cells exhibited a mixed morphology and appeared to be more elongated in the presence of DEX-OSM-HGF. Reverse-transcriptase polymerase chain reaction was used to delineate the most differentiating condition in terms of early (alpha-fetoprotein (AFP)), mid (albumin), and late-hepatic (glucose-6-phosphatase) markers in relation to growth factor presentation for both CE-ES and CD-ES cells. We report that following the most differentiating condition of DEX-OSM-HGF stimulation, CE-ES cells expressed increased levels of albumin and glucose-6-phosphatase, whereas the CD-ES cells showed low levels of AFP and marginal levels of albumin and glucose-6-phosphatase. These trends suggest that the membrane expression of E-cadherin in ES cells can elicit a marked response to growth factor stimulation and lead to the induction of later stages of hepatocytic maturation. Thus, cadherin-engineered ES cells could be used to harness the cross-talk between the hepatotrophic and cadherin-based signaling pathways for controlled acceleration of ES hepatodifferentiation.
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PMID:E-cadherin synergistically induces hepatospecific phenotype and maturation of embryonic stem cells in conjunction with hepatotrophic factors. 1616 33

Worldwide over 170 million people are chronically infected with the hepatitis C virus and hence at high risk to develop fatal liver disease. There is no vaccine available and the standard therapy [(pegylated) interferon alfa plus ribavirin] is only effective in 50-60% of patients and is associated with important side-effects. The discovery of novel antiviral strategies to selectively inhibit HCV replication has long been hindered by the lack of convenient cell culture models for the propagation of HCV. This hurdle has been overcome first with the establishment of the HCV replicon system in 1999 and, in 2005, with the development of robust HCV cell culture models. In recent years also mouse models have been elaborated that will be instrumental in assessing the in vivo efficacy of novel drugs. The viral serine protease and the viral RNA dependent RNA polymerase have shown to be excellent targets for selective anti-HCV therapy. Clinical studies with a limited number of HCV protease and polymerase inhibitors resulted in encouraging results. However, and not unexpected, preclinical evidence suggest that the virus may become rapidly resistant to such inhibitors. Combination therapy of drugs with different mode of action and resistance profiles may thus be required. Alternative strategies, such as the use of non-immunosuppressive cyclosporin A analogues with potent anti-HCV activity, may prove important, in particular since such compounds may have a resistance profile that is very different from that of protease or polymerase inhibitors.
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PMID:Selective inhibitors of hepatitis C virus replication. 1684 38


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