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Biomedical subjects

G R Pape

Publications and source records attributed to G R Pape.

At least 19 recordsLinked to original sources
PubMed1992

[Interferons].

The interferons are a family of proteins that are grouped together on the basis of their antiviral, antiproliferative and immunomodulatory effects. They are divided into three classes: alpha, beta, and gamma, which can be distinguished structurally, biochemically, and antigenically. Clinically they are used for the treatment of malignant tumors and of viral diseases, particularly of chronic viral hepatitis. The present role of interferons as therapeutic agents in the treatment of viral hepatitis will be critically discussed in the lecture.

Adjuvants, Immunologic↗
PubMed1992

Ursodeoxycholic acid for treatment of primary sclerosing cholangitis: a placebo-controlled trial.

The efficacy and safety of ursodeoxycholic acid for the treatment of primary sclerosing cholangitis were evaluated in a prospective, randomized, double-blind, placebo-controlled trial. Fourteen patients with primary sclerosing cholangitis documented by cholestatic serum enzyme pattern, liver histological appearance and endoscopic retrograde cholangiography were included in the trial. Six patients received ursodeoxycholic acid (13 to 15 mg/kg body wt/day), and eight patients received placebo. Two patients had to be withdrawn from the study, one because of UDCA-related diarrhea and the other because of worsening of the disease during placebo treatment. Patients in the ursodeoxycholic acid group improved significantly during 1 yr of treatment with respect to serum levels of bilirubin (median = -50%), alkaline phosphatase (median = -67%), gamma-glutamyltransferase (median = -53%), AST (median = -54%) and ALT (median = -36%) compared with the placebo group, but not with respect to serum levels of hydrophobic bile acids. During ursodeoxycholic acid treatment, histopathological features also improved significantly, as evaluated by multiparametric score. Expression of human leukocyte antigen class I molecules appeared to be markedly reduced on liver cells after ursodeoxycholic acid treatment. We conclude that ursodeoxycholic acid is beneficial in reducing disease activity in patients with primary sclerosing cholangitis.

Adolescent↗
PubMed1992

Precore mutant hepatitis B virus infection and liver disease.

The type of hepatitis B virus ("wild-type" or precore mutant) in anti-e antigen antibody-positive carriers, viral DNA levels in the serum, and core and e antigen expression in the liver were investigated to search for a possible correlation of these factors with the severity of liver damage. Two major groups of patients were found: the patients in group A were predominantly infected with precore mutant virus and had chronic active hepatitis, expressed nuclear/cytoplasmic core and e antigens in liver biopsy specimens, and usually had high levels of viral DNA in their serum; patients in group B were infected with a mixture of wild-type and mutant viruses, had predominantly chronic persistent hepatitis, showed weaker expression of nuclear core antigen with no cytoplasmic core or e antigen, and had low viremia. A few patients were infected with viruses without precore stop-codon mutation. These data indicate a high prevalence of precore mutant viruses in anti-e carriers with chronic liver disease and suggest that monitoring of virus sequence type and DNA level may be of prognostic value for liver disease sequelae.

Adult↗
PubMed1992

Hepatitis B virus genomes that cannot synthesize pre-S2 proteins occur frequently and as dominant virus populations in chronic carriers in Italy.

The heterogeneity of hepatitis B virus (HBV) pre-S sequences coding for envelope proteins was tested by DNA amplification and direct sequencing of viral genomes from sera of 22 unselected chronic carriers resident in Southern Italy. The sequences of the dominant viral genome populations from 15 carriers were very similar to known published "wildtype" HBV genomes and showed no deletions. In contrast, in the HBV populations of six patients, deletions in the pre-S region, mainly clustered at the amino terminal end of the pre-S2 region, were found. Four of these mutant genome populations and those from another patient cannot express pre-S2 proteins due to deletions or a mutation of the translation initiation codon. Emergence of the pre-S mutant viruses either during the natural course of infection or after interferon treatment was found in follow-up sera of one and two patients, respectively. These data indicate a high prevalence of pre-S mutant viruses which cannot express pre-S2 and normal-size pre-S1 proteins. This has important implications for the usefulness of diagnostic pre-S protein assays and possibly for interferon treatment and the efficacy of new vaccines containing pre-S proteins.

Amino Acid Sequence↗
PubMed1991

Polymorphic structure of the tumor necrosis factor (TNF) locus: an NcoI polymorphism in the first intron of the human TNF-beta gene correlates with a variant amino acid in position 26 and a reduced level of TNF-beta production.

Since a dysregulated synthesis of tumor necrosis factor alpha (TNF-alpha) may be involved in the pathogenesis of autoimmune diseases, it was of interest to precisely locate the recently reported NcoI restriction fragment length polymorphism (RFLP) of the TNF-alpha region. However, by mapping of 56.8 kb of overlapping cosmid clones and direct sequencing, we could localize the polymorphic NcoI restriction site within the first intron of the TNF-beta gene and not in the TNF-alpha gene. To study whether regulatory mechanisms are affected by this polymorphism, we analyzed the TNF-alpha/TNF-beta production of phytohemagglutinin-stimulated peripheral blood mononuclear cells of individuals homozygous for the TNF-beta NcoI RFLP by ELISA and concomitant Northern blot analysis. On days 2-4 after stimulation with mitogen, the TNFB*1 allele corresponding to a 5.3-kb NcoI fragment presented with a significantly higher TNF-beta response. A mRNA analysis demonstrated that higher protein levels of TNF-beta correlate also with increased amounts of TNF-beta transcripts. No allelic association was found in respect to TNF-alpha production. To further investigate a possible allelic influence on transcription, we determined the DNA sequence of 2 kb of the 5' portion of our cloned TNFB*2 allele and compared it with the available TNF-beta sequences. By computer-aided recognition motif search of DNA binding factors, we report putative binding sites conserved between mouse and man in the 5' flanking region as well as in intron 1 of the TNF-beta gene, found also in other cytokine promoter sequences. In addition, by polymerase chain reaction amplification and sequencing of 740 bp of the 5' part of TNF-beta of individuals typed homozygously for the NcoI RFLP, we could show that amino acid position 26 is conserved as asparagine in the TNFB*1 and as threonine in the TNFB*2 sequence. A previously reported, EcoRI RFLP in the 3' untranslated region of TNF-beta does not segregate with either of the two alleles. Thus, four TNFB alleles can be defined at the DNA level.

Alleles↗
PubMed1991

Prevalence and type of pre-C HBV mutants in anti-HBe positive carriers with chronic liver disease in a highly endemic area.

The sequence variability in the pre-C region of the hepatitis B virus (HBV) genome in the serum of 42 anti-HBe antibody positive carriers with chronic hepatitis B was studied by PCR and direct sequencing to determine prevalence and type of HBV pre-C mutants in a highly endemic area. Except for one, all patients were infected with viruses containing mutations in the pre-C region which prevent precore and e-antigen (HBeAg) expression: 33 were infected predominantly or exclusively with variants containing a stop codon; two had a mixture of wild-type and a pre-C stop codon mutant virus; three had precore variants with mutations of the pre-C initiation codon and two of them an additional stop codon; four had a frameshift mutation; and one had two stop codons. One patient was infected with viruses which contained a mutation creating an amino acid exchange which should not prevent precore and HBeAg expression. These data demonstrate that in an endemic area a higher prevalence and even broader spectrum of pre-C HBV mutants are found than has been recognized previously in anti-HBe positive patients with chronic hepatitis B.

Adult↗
PubMed1991

High prevalence and heterogeneity of HBV preC mutants in anti-HBe-positive carriers with chronic liver disease in southern Italy.

In this study we have investigated the prevalence and type of preC mutants in anti-HBe/HBV-DNA-positive patients with chronic hepatitis B in an endemic area. HBV-DNA from sera of 42 anti-HBe chronic HBV carriers was amplified by PCR and the preC region was directly sequenced. With one exception, all patients tested were found to be infected with viruses containing mutations in the preC region that predictably prevent precore and e antigen expression. Thirty-one patients were infected with HBV containing a stop codon; two had a mixture of wild-type and preC stop codon mutant; three had preC mutants with mutations in the translation initiation codon and two of them an additional stop codon; four had a frameshift mutation, and one had two stop codons. One patient was infected with a virus showing a mutation creating only an amino acid exchange which could not prevent HBeAg expression. The data obtained indicate a higher prevalence and heterogeneity of preC mutants in our geographical area than recognized so far in anti-HBe-positive carriers with chronic hepatitis B.

Base Sequence↗
PubMed1991

Selection for a pre-C stop codon mutation in a hepatitis B virus variant with a pre-C initiation codon mutation during interferon treatment.

Hepatitis B virus (HBV) variants with a stop codon, a mutated translation initiation codon or other mutations in the pre-C region which prevent e-antigen expression are highly prevalent in anti-HBe chronic carriers and can be positively selected from a mixed virus infection. Our laboratories recently described pre-C variants with two pre-C mutations which prevent HBeAg expression. Here we have investigated whether there is a selective pressure for acquisition of the second pre-C mutation. By direct sequencing of amplified HBV DNA from sera of a chronic carrier taken during a 6-year follow-up, we found that genomes of a virus population virtually all had a pre-C translation initiation codon mutation and about 50% had an additional stop codon mutation. With the onset of interferon treatment, the genomes with the stop codon mutation increased to more than 95% while the frequency of the translation initiation codon mutation in all genomes remained constant. These data indicate positive selection (possibly immune-mediated and HBeAg-targeted) for a second pre-C mutation. This putative enhancement of negative translational control may be present because a pre-C translation initiation codon mutation cannot totally prevent HBeAg expression and is therefore less frequent.

Adult↗
PubMed1991

Allelic variation in the TNF-beta gene does not explain the low TNF-beta response in patients with primary biliary cirrhosis.

Autoimmune disorders in humans are often associated with particular alleles of major histocompatibility genes. However, the chronic inflammatory liver disease primary biliary cirrhosis (PBC) has not been found to be correlated with certain haplotypes so far. Interestingly, an impaired production of tumour necrosis factor beta (TNF-beta) upon mitogen stimulation was observed for PBC patients, especially in the immunologically active stages of the disease. Furthermore, the identification of alleles of the TNF-beta gene which differ in one unique amino acid, and in the production of TNF-beta after phytohaemagglutinin stimulation, has prompted the idea of a possible linkage between the impaired TNF-beta response in PBC and the genetic prevalence of a certain TNF haplotype. We report here a rapid method for typing the TNFB*1 and TNFB*2 genes by a standard polymerase chain reaction. PBC patients (n = 60) as well as randomized healthy controls (n = 179) of the Munich area were studied for the occurrence of the TNF alleles. No deviation was found in the PBC collective (0.7) for the TNFB*2 distribution when compared with the control (0.67).

Alleles↗
PubMed1990

Antibodies to the RNase H domain of hepatitis B virus P protein are associated with ongoing viral replication.

Antibodies against the RNase H domain of human hepatitis B virus P protein(s) are frequent markers of acute and chronic virus infection (T. Weimer, K. Weimer, Z.-X. Tu, M.-C. Jung, G. R. Pape, and H. Will, J. Immunol. 143:3750-3756, 1989). In the present study, these antibodies were determined in serial serum samples of experimentally infected chimpanzees and naturally infected human patients with acute and chronic hepatitis B virus infection. Anti-P antibodies were found in the sera of both chimpanzees and humans early in infection shortly after the immunoglobulin M anti-HBc response; they persisted in chronic carriers with ongoing viral replication but declined and disappeared at the time of virus clearance from the sera. These data demonstrate that antibodies to the RNase H domain of the hepatitis B virus P protein are early markers of infection and a signal of ongoing virus replication. Falling titers indicate the decline or end of active virus production and may therefore be a prognostic sign of virus elimination in natural infection and after antiviral therapy.

Acute Disease↗
PubMed1990

Mapping of B-cell epitopes of the human hepatitis B virus X protein.

The immune response to the X protein of human hepatitis B virus (HBV) was studied by epitope mapping by using a set of MS2-HBx fusion proteins and synthetic peptides. Antibodies in sera of patients with acute and chronic HBV infection showed a multispecific immune response. Each serum contained antibodies to a different set of epitopes, which taken together cover most of the HBx sequence. Some of the epitopes were detectable only by immunoblotting with fusion proteins; others were detectable only by an enzyme-linked immunosorbent assay (ELISA) with synthetic peptides. The carboxy-terminal half of the HBx protein was preferentially recognized by antibodies from patients with chronic hepatitis and contained a short immunodominant antigenic region with at least two major nonoverlapping epitopes. Anti-HBx antibody titers as revealed by peptide ELISAs were highest and most frequent in patients with chronic hepatitis and usually low in acutely infected patients and asymptomatic carriers. The data demonstrate a remarkable qualitative and quantitative heterogeneity of the humoral HBx immune response which can be monitored by HBx-specific peptide ELISAs. Such tests may become useful diagnostic tools.

Amino Acid Sequence↗
PubMed1989

Immunogenicity of human hepatitis B virus P-gene derived proteins.

The frequency and specificity of antibodies to P-gene encoded proteins of human hepatitis B virus was tested in sera of acute and chronically infected patients with and without hepatocellular carcinoma (HCC). For antibody detection an immunoprecipitation gel assay was performed with radioactively labeled polypeptides produced by in vitro translation of RNA of different P-gene regions. Thus, five antigenic regions were identified. All anti-P antibody positive sera reacted with carboxy-terminal P-poly-peptides, a subset with polypeptides of the amino-terminal and middle region, and none reacted with P-protein derived from the most sequence variable region. Anti-P antibodies were detected at very high frequency in sera of acute (73%) and chronically infected patients without HCC (87%), but less often in HCC patients (27%). These data indirectly demonstrate the expression of most hepatitis B virus P-gene sequences and the immunogenicity of P-proteins in vivo. Moreover, they establish hepatitis B virus anti-P-antibodies as a frequent serologic marker of infection and identify the carboxy-terminal region of the P-protein(s) as immunodominant.

Acute Disease↗