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Biomedical subjects

A Manzin

Publications and source records attributed to A Manzin.

72 records · Page 4Linked to original sources
PubMed1987

Antibody response to individual cytomegalovirus structural proteins in different groups of subjects.

The antibody response to cytomegalovirus structural polypeptides in sera from three groups of acutely infected subjects was analyzed. Differences in number and types of polypeptides were noted. Immunoblotting could be used to distinguish sera from patients with acute cytomegalovirus hepatitis from convalescent sera by the detection of antibody to viral proteins of 82, 66, 62, and 55 kilodalton molecular weight at a high serum dilution.

Acute Disease↗
PubMed1987

Human growth hormone induced modulation of hepatitis B virus (HBV) gene expression.

A well characterized human hepatocellular carcinoma cell line (PLC/PRF/5) containing complete sequences of HBV-DNA in integrated form into host DNA and growing under serum-free conditions was used to test the effect of human growth hormone (hGH) on the expression of the integrated viral DNA. Data in our hands point to an early, specific effect of hGH on HBV-DNA integrated sequences which appears to be unrelated to the late effect on total protein synthesis. Moreover this approach enabled us to detect specific hGH receptors on the cell membrane of PLC/PRF/5 cell line.

Animals↗
PubMed1985

[Seroepidemiology of infection by hepatitis B virus in student nurses: some implications for vaccination policy].

To estimate the risk of hepatitis B virus (HBV) infection among student nurses, we measured the prevalence of HBV infection in 218 student nurses (192 female and 26 male nurses) and the annual attack rate in a subgroup of 117 subjects. In both studies sera were tested with an enzyme immunoassay for the presence of HBsAg, anti-HBc and anti-HBs. In the prevalence study 24 student nurses (11.1%) had a marker of prior HBV infection; the presence of both anti-HBc and anti-HBs was the most prevalent serologic pattern. 2 student nurses were HBsAg positive (0.9%). Prevalence of infection was strongly related to increasing age, while the occupation of the head of the family showed no effect. In the incidence study 7 subjects seroconverted in a year (6.2%): 6 acquired only anti-HBc and 1 only anti-HBs. These data suggested the hypothesis that the presence of anti-HBc alone (a pattern usually associated with past infections in which anti-HBs is no more detectable) may represent false positive results. The implications of such hypothesis are discussed with particular reference to prevaccination screening policy.

Adult↗
PubMedDate not supplied

Comparative effects of alpha, beta and gamma human interferons on a HBsAg-producing human hepatoma cell line.

The effects of all the three types of human interferons (alpha, beta and gamma) on a human hepatoma cell line with hepatitis B virus (HBV)-DNA sequences integrated into the host DNA and producing hepatitis B surface antigen (HBsAg) in culture medium were assayed. The aim of the present research was to test human interferon preparations in an in vitro system for hepatitis B virus, and to compare the observed effects. The results evidenced both the antireplicative activity principally showed by preparations of beta and gamma human interferons and the inhibition of HBsAg production by high concentrations of gamma human interferon.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Characterization of growth parameters of a human hepatoma cell line cultured under serum-free conditions.

The PLC/PRF/5 human hepatoma cell line has at least four complete series of hepatitis B virus (HBV)-DNA sequences integrated into the host DNA and produces hepatitis B surface antigen (HBsAg) and several serum proteins in the culture medium. In order to study serum proteins and HBsAg released by these cells under controlled conditions, the serum-free growth of several human hepatoma-derived cell lines was recently investigated. In this paper the growth of PLC/PRF/5 human hepatoma cell line in a serum- and hormone-free medium was investigated. The results represent a tool which might be used in pharmacological research, studies on hormone-binding and virus gene expression.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Viral load in samples from hepatitis C virus (HCV)-infected patients with various clinical conditions.

Molecular methods for the absolute quantitation of nucleic acids present in biological samples have recently been developed and applied in basic and in medical virology; these studies indicated that competitive polymerase chain reaction (PCR) and competitive reverse transcription PCR (cRT-PCR)-based methodologies are currently the methods of choice for quantifying DNA and RNA species present in clinical samples at low concentration. Recently, quantitative molecular techniques were developed to study the hepatitis C virus (HCV) pathogenic potential, the natural history of HCV-infected patients and the efficiency of antiviral therapies in real time. The pilot study reported here was carried out using a cRT-PCR application for the direct quantitation of HCV RNA molecules in plasma samples of infected individuals which was recently developed in our laboratory. Although sharp individual variability of viral load was documented in this study, the mean HCV RNA copy number detected in samples from untreated HCV-infected patients with various clinical conditions (chronic active hepatitis, cirrhosis, cryoglobulinaemia and chronic hepatitis) was substantially similar, with only one exception: in samples from patients tested positive for anti-liver-kidney microsomal (anti LKM1) auto-antibodies, a significantly lower HCV viraemia level was revealed. Additionally, HCV viraemia was monitored in four patients with sustained biochemical and histological response (at least 12 months) following interferon-alpha discontinuation.

Evaluation Studies as Topic↗
PubMedDate not supplied

Hepatitis B virus preC mutants in human hepatocellular carcinoma tissues.

A comparative analysis of preC sequences of hepatitis B virus (HBV) in human hepatoma (hepatocellular carcinoma; HCC) tissues and non-tumoral liver samples from HCC patients was performed. Ten out of 17 HCC tissue samples exhibited an amino acid substitution at the level of the distal cysteine residue of the HBV preC region, while generation of a TAG translational stop codon was observed in 4 of these samples. Interestingly, substitution of the distal cysteine residue was not observed in non-tumoral liver (available from 8 of the 17 patients), thus suggesting either that a selection among different HBV variants occurs in HCC cells, or that modifications to the conformation and stability of the HBV capsid protein may play a role in the process of selection and escape of transformed liver cells.

Base Sequence↗
PubMedDate not supplied

Direct detection of HBV preC mutants in heterogeneous viral populations by a modified DNA sequencing method.

A modified method for the direct sequencing of double-stranded DNA products of PCR amplification is described and has been applied to the analysis of hepatitis B virus (HBV) preC/C region in samples from persistently infected patients with chronic hepatitis. Data was obtained from both hepatitis B e antigen (HBeAg)-positive and -negative chronic carriers. A high prevalence of mixed viral populations (wild-type genomes and mutated sequences with a TAG stop codon in the distal preC region at position 1895-1897) was shown in the HBeAg-positive group; a homogeneous (either mutated or wild-type) viral population was detected in all but one of the long-term HBeAg-negative, untreated chronic carriers, thus suggesting that pre-core mutants can be rapidly generated and selected during the natural course of HBV infection.

Base Sequence↗
PubMedDate not supplied

Quantitation of hepatitis C virus RNA production in two human bone marrow-derived B-cell lines infected in vitro.

The ability of hepatitis C virus (HCV) to replicate in two B-cell lines, CE and TOFE, derived from bone marrow of healthy subjects was compared using qualitative and quantitative molecular methods. The presence of intracellular negative-stranded HCV RNA (replicative intermediate) was investigated by nested polymerase chain reaction (PCR) in the infected cultures at different times after infection. The amounts of positive-stranded HCV RNA (genomic RNA copies) synthesized and released from cells one week after in vitro infection were determined by competitive PCR after reverse transcription of viral RNA for the 5' viral untranslated region. In both cell lines, HCV RNA replication took place, but the TOFE cell line appeared to be a more efficient virus producer than the CE cell line. The TOFE cell line could be a valuable and reliable tool for basic and clinical HCV studies.

B-Lymphocytes↗
PubMedDate not supplied

Human monoclonal recombinant Fabs specific for HCV antigens obtained by repertoire cloning in phage display combinatorial vectors.

Molecular cloning of the antibody repertoire in phage display combinatorial vectors is a powerful method enabling the dissection of the immunoresponse against a given pathogen. In this paper we describe the construction of a combinatorial library displayed on phage surface, containing the antibody repertoire of a patient with high serological response against hepatitis C virus (HCV) antigens. Following selection of the library against solid-phase-bound antigen, sixteen human antibody Fab fragments able to bind to HCV-specific antigens were generated and studied for binding characteristics. The majority of them appeared to have specificity for the HCV c33 peptide. All the clones reacting with the c33 peptide shared the same heavy-chain CDR3 sequence. This is the first report of molecular cloning in a combinatorial phage display vector of the antibody repertoire of an anti-HCV-positive patient.

Amino Acid Sequence↗
PubMedDate not supplied

Dynamics of viral quasispecies in hepatitis C virus infection.

The genomic heterogeneity of hepatitis C virus (HCV) was addressed in the different phases of HCV infection. Viral sequences of the HVR-1 and NS5a regions were obtained by reverse transcription polymerase chain reaction from plasma samples of two patients with acute type-C hepatitis and two patients with chronic infection treated with interferon. The data indicate that in primary infection different degrees of genomic heterogeneity in biologically important viral regions might be associated with different clinical outcomes.

Acute Disease↗
PubMedDate not supplied

Hepatitis C virus infection of a Vero cell clone displaying efficient virus-cell binding.

The susceptibility of Vero cells and derivative cell clones to hepatitis C virus (HCV) infection was assayed by qualitative and quantitative polymerase chain reaction (PCR)-based methods. Cell extracts from Vero cells inoculated with HCV were tested for the presence of both positive and negative strands of HCV RNA; in parallel, cell-free HCV genomes were assayed in culture supernatant fluids. Quantitation of genomic HCV RNA molecules in infected cells by competitive reverse transcription PCR (cRT-PCR) indicated that HCV replication was more efficient in a derivative clone (named clone 10) than in parental Vero cells or other clones under study. Analysis of HCV-binding to cell receptors, performed by cRT-PCR quantitation of viral particles adsorbed to the cell surface, demonstrated a 10-fold higher virus-binding level of clone 10 than that of parental Vero cells. The results shown here indicate that the Vero clone 10 may constitute an efficient model system for analysing early events in HCV infection as well as a source of virus for diagnostic and biotechnological applications.

Animals↗
PubMedDate not supplied

Exacerbation of chronic hepatitis D during interferon alpha administration.

Acute and severe impairment of liver function with jaundice and ascites occurred in two out of seven patients with chronic hepatitis D during interferon alpha administration (10 MU three times a week). Both of them were young women with histological diagnoses of moderate to severe chronic hepatitis and cirrhosis with no signs of portal hypertension. Only a slow and partial recovery was observed after interferon withdrawal. Autoantibodies against basal cell layer tested positive in these two patients. In the remaining five patients with hepatitis D who did not experience liver impairment during interferon administration, basal cell layer antibodies were found only in one case. We conclude that severe decompensation of liver cirrhosis related to hepatitis D may occur during interferon administration. Positivity of basal cell layer antibodies may be associated with the risk of developing such an adverse event but our data are not sufficient to prove this association.

Adult↗
PubMedDate not supplied

Humoral immune response and natural killer activity in patients with mixed cryoglobulinemia.

OBJECTIVE: Based on serological and molecular evidence of hepatitis C virus (HCV) infection in a significant proportion of patients with mixed cryoglobulinemia (MC), a direct association between HCV and MC has been suggested. The goal of the present study was to investigate the role played by HCV and by the immune response to the virus in the pathogenesis of mixed cryoglobulinemia. METHODS: A competitive reverse transcription polymerase chain reaction was employed to evaluate the concentrations of specific HCV RNA sequences in different clinical specimens (plasma, sera, cryoprecipitates, bone marrow and peripheral blood cells). Using recombinant and synthetic peptides covering the HCV core, envelope 1 (E1) and nonstructural regions 4 (NS4) and 5 (NS5), the humoral immune response in a group of MC patients was assessed with an enzyme-linked immunosorbent assay. Natural killer (NK) cell activity was estimated using a 4 hr 51 Cr release assay. RESULTS: Quantitation of the RNA molecules in the biological samples confirmed an increased virion concentration in cryoprecipitates from 13/15 patients with mixed cryoglobulinemia. Analysis of the humoral immune response against the synthetic peptides suggested a distinct response to HCV antigens in MC patients when compared to patients with HCV infection but without serological evidence of cryoglobulinemia. Unstimulated NK cell functioning was below the normal range in all patients tested. However, peripheral blood mononuclear cells showed no enhancement of NK activity by the interferon inducer polyinosinic acid:polycytidilic acid. Enhancement by interferon-alpha was normal, suggesting an impairment in interferon production. CONCLUSION: The quantitative data are in line with the hypothesis of a direct or indirect role of HCV in mixed cryoglobulinemia. The abnormal immune response could be involved in the onset and persistence of HCV infection, and possibly in the appearance of cryoglobulinemia.

Antibody Formation↗
PubMedDate not supplied

Characterization of hepatitis C virus genotypes in an hemodialysis unit in Paysandú, Uruguay.

Hepatitis C virus types were investigated by using samples from eight sero-reactive and PCR positive patients attending our Hemodialysis Unit en Paysandú, Uruguay. After HCV RNA detection by reverse transcription and polymerase chain reaction, HCV genotyping was carried out by a nested PCR amplification, using type specific primers of HCV core region. These results were confirmed using a method based upon reverse hybridation of amplified products by enzyme-labeled type-specific probes to portions of the 5' UTR region. HCV genotypes were assigned according to Simmonds' classification. Type 1b was found in five patients, type 3a was found in one and one patient was not classified. There was a patient who became PCR negative at the moment the genotyping was carried out.

Aged↗